Original Research Paper
Demonstration of ameliorative effect of lacosamide: in a rat model of sepsis-induced critical illness polyneuropathy Volkan Solmaz1, Du¨rdane Aksoy2, Mustafa Yılmaz3, Enes Eser4, Oytun Erbas5 1
Department of Neurology, Turhal State Hospital, Tokat, Turkey, 2Faculty of Medicine, Department of Neurology, Gaziosmanpasa University, Tokat, Turkey, 3Faculty of Medicine, Department of Neurology, Mug˘la University, Mug˘la, Turkey, 4Faculty of Medicine, Department of Orthopedics and Traumatology, Gaziosmanpasa University, Tokat, Turkey, 5Faculty of Medicine, Department of Physiology, Gaziosmanpasa University, Tokat, Turkey
Objectives: Critical illness neuropathy (CIN) is a condition that may occur in diseases with severe systemic response, particularly in sepsis. The aim of this study is to investigate the potential anti-inflammatory and lipid-peroxidation inhibiting activities of lacosamide by measuring tumour necrotizing factor-alpha (TNF-alpha), C-reactive protein (CRP), malondialdehyde (MDA) and white blood cells (WBC) using electroneuromyography (ENMG) in rats with sepsis-induced critical illness neuropathy (SICIN). Methods: Cecal ligation and puncture (CLP) procedure was performed on 39 rats to induce a sepsis model. The study groups were designed as follows: Group 1: normal (nonoperative); Group 2: (shamoperated); Group 3: CLP (untreated group); Group 4: CLP and lacosamide 20 mg/kg; Group 5: CLP and lacosamide 40 mg/kg. TNF-alpha, C reactive protein, MDA and WBC levels was measured and compound muscle action potential (CMAP) distal latans, amplitudes were measured by using ENMG in rats with SICIN. Results: When untreated sepsis group was compared with both control and sham groups, CMAP amplitudes and latans were significantly lower (Pv000.1). When CLP, CLPzlacosamide 20 mg/kg and CLPzlacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha and MDA were significantly higher in the untreated CLP group (F 512.74, Pv0.0001), (F 519.43, Pv0.05). In the CLPzlacosamide 40 mg/kg group, CRP levels were significantly lower only compared to the CLP group (Pv0.001). Discussion: We have showed that lacosamide may have beneficial effects on early SICIN by its potential anti-inflammatory and lipid peroxidation inhibiting activities; however, further comprehensive studies are required to clarify these effects. Keywords: Critical illness polyneuropathy, Lacosamide, Electroneuromyography, TNF-alpha
Introduction Critical illness neuropathy (CIN) is a condition that may occur in diseases with severe systemic response, particularly in sepsis,1 and it’s most evident clinical feature is muscle weakness, which complicates weaning of patients in the intensive care and leads to serious financial loss.2 Although its prevalence varies between different populations, it may increase up to 100% in 70% of patients with sepsis when accompanied with multi-organ failure in case of no improvement in sepsis.3 The main outcome of diagnostic electrophysiological analysis in patients, who developed CIN, was the decreased amplitude of compound muscle action potentials (CMAPs) (i.e. axonal degeneration).4 Unfortunately, results from
Correspondence to: Volkan Solmaz, MD, Department of Neurology, Turhal State Hospital, Tokat, Turkey, Tel: þ905069043459; Fax: þ 903562133179. Email: [email protected]
ß W. S. Maney & Son Ltd 2015 DOI 10.1179/1743132815Y.0000000040
relevant studies are unclear. Although the underlying mechanism of sepsis-induced critical illness neuropathy (SICIN) has not been elucidated, several theories have been proposed for its pathogenesis. The humoral response evoked by sepsis disturbs the circulation in the vessels supplying the nerve, playing a significant role in development of the disease.1 It is known that during the development of a humoral response, tumour necrotizing factor-alpha (TNF-alpha), interleukins (IL)-1, -2, and -6, and reactive oxygen radicals are released from the endothelium of the vessels, and these molecules alter permeability of the vessel wall, decreasing oxygen supply to the nerve, and resulting in axonal degeneration.5 Another mechanism implicated in the pathogenesis of SICIN is the alteration in permeability of the sodium channel during development of the disease, and recent studies have demonstrated that the permeability of the voltage-dependent sodium channels is blocked
Neurological Research
2015
VOL .
37
NO .
9
797
Solmaz et al.
Demonstration of ameliorative effect of lacosamide: in a rat model
by the TNT-alpha released from the capillary endothelium during sepsis.6,7 Based on this, it may be suggested that any agent supressing the aforementioned inflammatory changes may be involved in development of SICIN. Lacosamide, i.e., R-2-acetamido-N-benzyl3-methoxypropionamide, is a newly developed antiepileptic.8 Literature shows studies of lacosamide on neuropathic pain; one study has demonstrated that vincristine-induced model of neuropathy has protective and disease-modifying characteristics,9 whereas another one has revealed positive effects of the agent on dorsal horn neuronal responses by modulating the sodium channels.10,11 However, no study has evaluated the effect of the agent on SICIN as well as its anti-inflammatory and neuroprotective characteristics. The aim of this study is to investigate the potential anti-inflammatory and lipid-peroxidation inhibiting activities of lacosamide by measuring TNF-alpha, C-reactive protein (CRP), malondialdehyde (MDA) and white blood cells (WBC) using electroneuromyography (ENMG) in rats with SICIN.
Materials and methods Animals In this study, 52 adult male albino Sprague Dawley rats weighing 200–250 g were used. Animals were fed ad libitum and housed in pairs in steel cages in a temperature-controlled environment (22 + 2uuC) of 12-h light/dark cycles. The experimental procedures were approved by the Animal Research Ethics Committee of the Gaziosmanpasa University (under approval no; 2013 HADYEK-30). All animal studies strictly conformed to The Animal Experiment Guidelines of the Committee for Animal Care.
Experimental procedures Rats were randomly assigned into five groups, and cecal ligation and puncture (CLP) procedure was performed on 39 rats to induce a sepsis model. Twelve rats died during the first 24 h following the surgical procedure, and they were excluded from the study. There was no mortality in the sham-operated group. The study groups were designed as follows: Group 1: normal (nonoperative and orally fed control, n58); Group 2: sham-operated (n58); Group 3: CLP (untreated group, n57); Group 4: CLP and lacosamide 20 mg/kg (Vimpat, UCB Pharma) intraperitoneal (i.p.) (n58); Group 5: CLP and lacosamide 40 mg/kg i.p. (n58). For the surgical procedure, rats were anesthetized by intraperitoneal injection of a combination of ketamine hydrochloride at a dose of 50 and 7 mg/kg xylazine hydrochloric (Alfazyne; Alfasan International BV, Woerden, Holland).
798
Neurological Research
2015
VOL .
37
NO .
9
Under aseptic conditions, a 3 cm midline laparotomy was performed to allow the exposure of the cecum with adjoining intestine. The cecum was ligated tightly with a 3.0 silk suture at its base under the iliocecal valve and punctured once with a 22-gauge needle. The cecum was then gently squeezed to extrude a small amount of feces from the perforation site. The cecum was returned to the peritoneal cavity, and the laparotomy incision was closed with a 4.0 polyglactin 910 suture. Following surgery, animals were allowed a recovery period, and then they were returned to their cages. In the sham group, under aseptic conditions, only laparotomy was performed on rats, but their cecum was neither ligated nor punctured. In this model, rats were considered septic 5 h following CLP.12 All treatments were performed during first hour of the surgical procedure.
Measurement of plasma TNF-alpha and CRP levels Plasma TNF-alpha and CRP levels were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kit (Biosciences). The plasma samples were diluted 1:2 and TNF-alpha and CRP levels were determined in duplicate according to the manufacturer’s instructions.
Measurement of lipid peroxidation Lipid peroxidation was determined in plasma samples by measuring MDA levels as thiobarbituric acid reactive substances. Briefly, trichloroacetic acid and TBARS reagent were added to the plasma samples, then mixed and incubated at 100uuC for 60 min. After cooling on ice, the samples were centrifuged at 3 000 rpm for 20 min, and the absorbance of the supernatant was read at 535 nm. MDA levels were expressed as nM, and tetraethoxypropane was used for calibration.
Peripheral Neutrophil Count Peripheral blood smears were stained with WrightGiemsa stain to evaluate the circulating neutrophils obtained at 24 h. Five high-power fields per slide (|200 magnification) were randomly selected, and the number of neutrophils per high power field was manually counted. A circulating neutrophil count was obtained by multiplying the average value by 1 000.
Electrophysiological recordings Electrophysiological recordings, electromyography (EMG) studies were performed 24 h after surgery. EMG was obtained three times from the right sciatic nerve and stimulated supramaximally (intensity 10 V, duration 0.05 ms, frequency 1 Hz, in the range of 0.5–5 000 Hz, 40 kHz/s with a sampling rate) using a Medelec Synergy (Oxford Instruments, Surrey, UK) bipolar stimulating electrode inserted subcutaneously
Solmaz et al.
at the sciatic notch. CMAPs were recorded from 2 to 3 interosseous muscles with unipolar platinum electrodes. Data were evaluated using Medelec-Oxford Synergy Quantitative EMG Test Software with distal latency and amplitude of the CMAP as the parameters. During the EMG recordings, rectal temperatures of the rats were monitored by a rectal probe (HP Viridia 24-C; Hewlett-Packard Company, Palo Alto, CA), and the temperature of each rat was kept at approximately 36–37uuC by a heating pad. Following EMG recordings, animals were euthanised, and blood samples were collected by cardiac puncture for biochemical measurements. They were centrifuged at 3 000 rpm for 10 min at room temperature and stored at ((20uuC until assay.
Statistical analysis Statistical evaluation was performed using SPSS version 15.0 for Windows. The Shapiro–Wilk test was used to see parametric and non-parametric distribution. All data were normally distributed, and thus parametric variables were compared using the Student’s t-test, Analysis of Variance with post hoc analysis using the Tuckey test. Results are presented as mean SEM. A Pv0.05 was accepted as statistically significant.
Results Evaluation of groups by the amplitude of CMAP When untreated sepsis group was compared with both control and sham-operated groups, CMAP amplitudes were significantly lower (Pv000.1), but no significant differences were found between the sham-operated group and the control group (Pw0.05). When CLP and CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, the CMAP amplitudes were significantly lower in the untreated CLP group (F514.67, Pv0.001). A post hoc analysis using the Tuckey test showed that both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups had better CMAP amplitudes only compared to the CLP group (Pv0.001 and Pv0001, respectively). However, no significant differences were found between CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg group (Pw0.05) (Table 1, Fig. 1).
Evaluation of groups by the latency of CMAP When untreated sepsis groups were compared with both control and sham-operated groups, latency
Demonstration of ameliorative effect of lacosamide: in a rat model
periods for CMAP were significantly lower (Pv000.1), but no significant differences were found between the sham-operated groups and the control groups (Pw0.05). When CLP and CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, the latency periods for CMAP were significantly lower in the untreated CLP groups (F518,23, Pv0.001). A post hoc analysis using the Tuckey test showed that both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups had better latency periods for CMAP only compared to the CLP groups (Pv0.001 and Pv001, respectively). When CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, latency periods for CMAP were better in favour of CLP plus lacosamide 40 mg/kg (Pv0.05) (Table 1, Fig. 1).
Evaluation of groups by the plasma levels of TNF-alpha There were no significant differences between the normal groups and the sham-operated groups in plasma levels of TNF-alpha (Pw0.05). When individually compared with the CLP groups, the TNFalpha levels were significantly higher than in both normal groups and sham-operated groups (Pv0.000, Pv0.0001). When CLP, CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha were significantly higher in the untreated CLP groups (F512.74, Pv0.0001). A post hoc analysis using the Tuckey test showed that plasma levels of TNF-alpha were lower in both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups only compared to the those in the CLP groups (Pv0.001 and Pv001, respectively). When CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha were better in favour of CLP plus lacosamide 40 mg/kg (Pv0.0001) (Table 2).
Evaluation of groups by plasma levels of MDA There were no significant differences between the normal groups and the sham-operated groups in plasma levels of MDA (Pw0.05). When individually compared with the CLP groups, plasma levels of MDA were significantly higher than in both normal groups and sham-operated groups (Pv0.001,
Table 1 Results were presented as + SEM
CMAP latency (ms) CMAP amplitude (mV)
Normal control (n58)
Sham operated (n58)
2.66+ 0.03 8.96+ 0.11
2.72+ 0.02 8.72+ 0.12
CLP (n57)
CLP and lacosamide 20 mg/kg (n58)
CLP and lacosamide 40 mg/kg (n58)
4.1+ 0.07** 4.4+ 0.29**
3.27+ 0.05# 6.82+ 0.18#
2.91+ 0.08## 7.14+ 0.25#
Pv0.0001, different from normal and sham-operated groups; #Pv0.001; ##Pv0.0001 different from CLP group.
**
Neurological Research
2015
VOL .
37
NO .
9
799
Solmaz et al.
Demonstration of ameliorative effect of lacosamide: in a rat model
Figure 1 Samples of CMAP recorded from (A) Normal group, (B) Sham group, (C) CLP group, (D) CLP and lacosamide 40 mg/kg. Table 2 Results were presented as + SEM
MDA (nM) TNF-alpha CRP (mg/dL) WBC/mL
Normal control (n58)
Sham operated (n58)
CLP (n57)
CLP and lacosamide 20 mg/kg (n58)
72.1+ 8.6 22.8+ 3.2 0.33+ 0.09 4.1+ 0.5
98.3+ 10.6 24.9+ 1.2 0.49+ 0.11 4.4+ 0.3
182.4+ 13.9* 254.2+ 11.4{ 0.84+ 0.16** 9.8+ 1.1**
148.6+ 13.1# 186.4+ 10.3{ 0.76+ 0.23 9.5+ 1.05
*Pv0.001; **Pv0.05; {Pv0.000, different from normal and sham-operated groups; #Pv0.05, CLP group.
Pv0.001). When CLP, CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, plasma levels of MDA were significantly higher in the untreated CLP groups (F519.43, Pv0.05). A post hoc analysis using the Tuckey test showed that plasma levels of MDA were lower in both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide40 mg/kg groups only compared to the those in the CLP groups (Pv0.05 and Pv001, respectively). When CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, no significant difference was observed in plasma levels of MDA between the tow groups (Pw0.05) (Table 2).
Evaluation of groups by plasma levels of CRP and WBC A comparison of CRP and WBC counts between the normal groups and sham-operated groups showed that the difference was not statistically significant (Pw0.05); however, when untreated CRP group was compared indiviually with the control and shamoperated groups, CRP and WBC levels were
800
Neurological Research
2015
VOL .
37
NO .
9
CLP and lacosamide 40 mg/kg (n58) 115.8+ 9.5## 152.4+ 9.6{ 0.45+ 0.17## 9.2+ 1.6
##
Pv0.001; {Pv0.000 different from
significantly higher (Pv0.05). A comparison among CLP and CLP plus lacosamide 20 mg/kg, CLP plus lacosamide 40 mg/kg groups showed a significant difference in plasma levels of WBC and CRP (F518.35, Pv0.001). A post hoc analysis using the Tukey test showed no significant difference in WBC and CRP levels in the CLP plus lacosamide 20 mg/kg group compared to the untreated CLP group (Pw0.05); however in the CLP plus lacosamide 40 mg/kg group, CRP levels were significantly lower only compared to the CLP group (Pv0.001), and no significant difference was found in WBC levels (Pw0.05) (Table 2).
Discussion Despite many studies, CIN remains a major cause of morbidity and mortality in the intensive care, and its exact pathogenesis is still unclear.2 The condition is usually diagnosed with clinical and electroneuromyographic methods. Reduced CMAP amplitudes, which is a sign of axonal damage as shown by ENMG, are critical for diagnosis of the disease.13 Accordingly, in our study, ENMG showed significant reductions in CMAP amplitudes in the sepsis-induced groups
Solmaz et al.
compared to the control group, but CMAP amplitudes were significantly better in both dosages of lacosamide 20 and 40 mg/kg; however, the effect of lacosamide was not dose-dependent (no significant differences between 20 and 40 mg/kg). To the best of authors’ knowledge, in the literature there is no study which evaluated anti-inflammatory and lipid peroxidation inhibiting activities of lacosamide in early SICIN. During sepsis, elevated levels of cytokines including TNF-alpha, heat shock proteins, free oxygen radicals and fat acid metabolites are suggested to have an impact on the microvascular circulation, resulting in impaired supply to the nerve and axonal degeneration.14 According to this, it is possible to propose that any agent inhibiting such events induced by sepsis may have beneficial effects on SICIN. A study on the effects of melatonin and oxytocin on the CIN showed that both oxytocin and melatonin reduced TNF-alpha, leading to anti-inflammatory effects and suppressed oxidative stress, displaying antioxidative effects.15 Similarly, in this study, plasma levels of TNF-alpha WBC and CRP are significantly higher in the CLP group than both in control and sham-operated groups, and furthermore levels of MDA, a product of lipid peroxidation, are higher in the CLP group. The inflammatory markers and MDA levels are significantly reduced in the CLP group receiving lacosamide, which suggests that anti-inflammatory and lipid peroxidation inhibiting activities of lacosamide may be beneficial in SICIN. Kevin et al. indicated that acquired sodium channelopathy may be involved in the pathogenesis of CIN, and reported that voltage-dependent sodium channels were blocked by TNF-alpha, reducing excitability of the nerve,7 and a similar study proposed that TNF-alpha may be involved in the pathogenesis of critical illness polyneuropathy through activation of protein kinase C, and downregulation of the sodium channels in skeletal muscles.6 In this study, reduced plasma levels of TNF-alpha in the sepsis groups receiving lacozamide suggest that TNF-alpha might have inhibited these potential effects displaying beneficial effects on SICIN. A study by Bee and Dickenson reported the effects of lacosamide on dorsal horn neuronal responses through modulation of sodium channels in a rat model of neuropathy,10 and the sodium channel modulating effects of this agent were reported by other studies.11,16 Another mechanism implicated in the pathogenesis of SICIN is the disruption of vascular permeability by releasing of inflammatory cytokines and Na-K pump dysfunction secondary to it so that resting membrane potential does not return to the normal level.17 Accordingly, lacosamide, which was reported to have sodium channel modulatory effects by previous studies, might have beneficial effects on SICIN by modulating the
Demonstration of ameliorative effect of lacosamide: in a rat model
disrupted Na-K pump, and as a matter of fact, positive effects of levetiracetam, another antiepileptic which is considered to have a similar mechanism, have been reported in SICIN.18 In another study, Bettina et al. reported that lacosamide was very effective in myalgia induced by TNFalpha in a rat model, even had a better analgesic effect than pregabalin and gabapentin when administered at a dose of 30 mg/kg.19 Although levels of TNF-alpha were not measured in the aforementioned study, a question may arise to whether the agent showed its analgesic effects through reduction of TNF-alpha levels, considering the results of our study. As a result of a literature review, the authors believe that this study is important as it is the first study which has evaluated the effects of lacosamide on CIN; however, the underlying mechanism of this agent remains unclear. One major limitation of our study was a failure to study the effects of lacosamide on sodium channels. In conclusion, we showed that lacosamide may have beneficial effects on early SICIN by its potential anti-inflammatory and lipid peroxidation inhibiting activities. However, further comprehensive studies are required to clarify how these effects occur and also chronic effects of lacosamide in SICIN.
Disclaimer Statements Contributors Volkan Solmaz: study design, writing, experimental procedure. Durdane Aksoy: writing, literature screening. Mustafa Yılmaz: editing, writing. Enes Eser: experimental procedure. Oytun Erbas: study design, writing, experimental procedure. Funding None. Conflicts of interest The authors declarers that there is no conflict of interests. Ethics approval Our manuscript has been under approval (no; 2013 HADYEK-30).
References 1 Bolton CF. Neuromuscular manifestations of critical illness. Muscle Nerve. 2005;32(2):140–63. 2 Stevens RD, Dowdy DW, Michaels RK, Mendez-Tellez PA, Pronovost PJ, Needham DM. Neuromuscular dysfunction acquired in critical illness: a systematic review. Intensive Care Med. 2007;33(11):1876–91. 3 Zochodne DW, Bolton CF, Wells GA, Gilbert JJ, Hahn AF, Brown JD, et al. Critical illness polyneuropathy. A complication of sepsis and multiple organ failure. Brain. 1987;110(Pt 4):819–41. 4 Tennila A, Salmi T, Pettila V, Roine RO, Varpula T, Takkunen O. Early signs of critical illness polyneuropathy in ICU patients with systemic inflammatory response syndrome or sepsis. Intensive Care Med. 2000;26(9):1360–3. 5 Hermans G, De Jonghe B, Bruyninckx F, Van den Berghe G. Clinical review: critical illness polyneuropathy and myopathy. Crit Care. 2008;12(6):238. 6 Guillouet M, Gueret G, Rannou F, Giroux-Metges MA, Gioux M, Arvieux CC, et al. Tumor necrosis factor-downregulates sodium current in skeletal muscle by protein kinase C activation: involvement in critical illness polyneuromyopathy. Am J Physiol Cell Physiol. 2011;301:1057–63.
Neurological Research
2015
VOL .
37
NO .
9
801
Solmaz et al.
Demonstration of ameliorative effect of lacosamide: in a rat model
7 Novak KR, Nardelli P, Cope TC, Filatov G, Glass JD, Khan J, et al. Inactivation of sodium channels underlies reversible neuropathy during critical illness in rats. J Clin Invest. 2009;119(5): 1150–8. 8 Hao JX, Stohr T, Selve N, Wiesenfeld-Hallin Z, Xu XJ. Lacosamide, a new anti-epileptic, alleviates neuropathic pain-like behaviors in rat models of spinal cord or trigeminal nerve injury. Eur J Pharmacol. 2006;553(1–3):135–40. 9 Geis C, Beyreuther BK, Stohr T, Sommer C. Lacosamide has protective disease modifying properties in experimental vincristine neuropathy. Neuropharmacology. 2011;61(4):600–7. 10 Bee LA, Dickenson AH. Effects of lacosamide, a novel sodium channel modulator, on dorsal horn neuronal responses in a rat model of neuropathy. Neuropharmacology. 2009;57(4):472–9. 11 Sheets PL, Heers C, Stoehr T, Cummins TR. Differential block of sensory neuronal voltage-gated sodium channels by lacosamide [(2R)-2-(acetylamino)-N-benzyl-3-methoxypropanamide], lidocaine, and carbamazepine. J Pharmacol Exp Ther. 2008; 326(1):89–99. 12 Iseri SO, Sener G, Saglam B, Gedik N, Ercan F, Yegen BC. Oxytocin protects against sepsis-induced multiple organ damage: role of neutrophils. J Surg Res. 2005;126(1):73–81. 13 Farivar BS, Eiref SD, Leitman IM. Strategies to prevent sepsisinduced intensive care uniteacquired weakness: are there any
802
Neurological Research
2015
VOL .
37
NO .
9
14 15
16
17 18
19
options? Commentary on ‘‘Comparison of melatonin and oxytocin in the prevention of critical illness polyneuropathy in rats with surgically induced sepsis’’. J Surg Res. 2013;185:39–42. Leitman IM. Modulating the inflammatory response in sepsis. J Surg Res. 2011;171(2):e183–5. ¨ , Taskiran D. Erbas O, Ergenoglu AM, Akdemir A, Yeniel AO Comparison of melatonin and oxytocin in the prevention of critical illness polyneuropathy in rats with experimentallyinduced sepsis. J Surg Res. 2013;183(1):313–20. Errington AC, Stohr T, Heers C, Lees G. The investigational anticonvulsant lacosamide selectively enhances slow inactivation of voltage-gated sodium channels. Mol Pharmacol. 2008;73(1): 157–69. Fang C, Bourdette D, Banker G. Oxidative stress inhibits axonal transport: implications for neurodegenerative diseases. Mol Neurodegener. 2012;7:29. Erbas O, Yeniel AO, Akdemir A, Ergenoglu AM, Yilmaz M, Taskiran D, et al. The beneficial effects of levetiracetam on polyneuropathy in the early stage of sepsis in rats: electrophysiological and biochemical evidence. J Invest Surg. 2013; 26(6):312–8. Beyreuther BK, Geis C, Stohr T, Sommer C. Antihyperalgesic efficacy of lacosamide in a rat model for muscle pain induced by TNF. Neuropharmacology. 2007;52(5):1312–7.
Demonstration of ameliorative effect of lacosamide: in a rat model of sepsis-induced critical illness polyneuropathy Volkan Solmaz1, Du¨rdane Aksoy2, Mustafa Yılmaz3, Enes Eser4, Oytun Erbas5 1
Department of Neurology, Turhal State Hospital, Tokat, Turkey, 2Faculty of Medicine, Department of Neurology, Gaziosmanpasa University, Tokat, Turkey, 3Faculty of Medicine, Department of Neurology, Mug˘la University, Mug˘la, Turkey, 4Faculty of Medicine, Department of Orthopedics and Traumatology, Gaziosmanpasa University, Tokat, Turkey, 5Faculty of Medicine, Department of Physiology, Gaziosmanpasa University, Tokat, Turkey
Objectives: Critical illness neuropathy (CIN) is a condition that may occur in diseases with severe systemic response, particularly in sepsis. The aim of this study is to investigate the potential anti-inflammatory and lipid-peroxidation inhibiting activities of lacosamide by measuring tumour necrotizing factor-alpha (TNF-alpha), C-reactive protein (CRP), malondialdehyde (MDA) and white blood cells (WBC) using electroneuromyography (ENMG) in rats with sepsis-induced critical illness neuropathy (SICIN). Methods: Cecal ligation and puncture (CLP) procedure was performed on 39 rats to induce a sepsis model. The study groups were designed as follows: Group 1: normal (nonoperative); Group 2: (shamoperated); Group 3: CLP (untreated group); Group 4: CLP and lacosamide 20 mg/kg; Group 5: CLP and lacosamide 40 mg/kg. TNF-alpha, C reactive protein, MDA and WBC levels was measured and compound muscle action potential (CMAP) distal latans, amplitudes were measured by using ENMG in rats with SICIN. Results: When untreated sepsis group was compared with both control and sham groups, CMAP amplitudes and latans were significantly lower (Pv000.1). When CLP, CLPzlacosamide 20 mg/kg and CLPzlacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha and MDA were significantly higher in the untreated CLP group (F 512.74, Pv0.0001), (F 519.43, Pv0.05). In the CLPzlacosamide 40 mg/kg group, CRP levels were significantly lower only compared to the CLP group (Pv0.001). Discussion: We have showed that lacosamide may have beneficial effects on early SICIN by its potential anti-inflammatory and lipid peroxidation inhibiting activities; however, further comprehensive studies are required to clarify these effects. Keywords: Critical illness polyneuropathy, Lacosamide, Electroneuromyography, TNF-alpha
Introduction Critical illness neuropathy (CIN) is a condition that may occur in diseases with severe systemic response, particularly in sepsis,1 and it’s most evident clinical feature is muscle weakness, which complicates weaning of patients in the intensive care and leads to serious financial loss.2 Although its prevalence varies between different populations, it may increase up to 100% in 70% of patients with sepsis when accompanied with multi-organ failure in case of no improvement in sepsis.3 The main outcome of diagnostic electrophysiological analysis in patients, who developed CIN, was the decreased amplitude of compound muscle action potentials (CMAPs) (i.e. axonal degeneration).4 Unfortunately, results from
Correspondence to: Volkan Solmaz, MD, Department of Neurology, Turhal State Hospital, Tokat, Turkey, Tel: þ905069043459; Fax: þ 903562133179. Email: [email protected]
ß W. S. Maney & Son Ltd 2015 DOI 10.1179/1743132815Y.0000000040
relevant studies are unclear. Although the underlying mechanism of sepsis-induced critical illness neuropathy (SICIN) has not been elucidated, several theories have been proposed for its pathogenesis. The humoral response evoked by sepsis disturbs the circulation in the vessels supplying the nerve, playing a significant role in development of the disease.1 It is known that during the development of a humoral response, tumour necrotizing factor-alpha (TNF-alpha), interleukins (IL)-1, -2, and -6, and reactive oxygen radicals are released from the endothelium of the vessels, and these molecules alter permeability of the vessel wall, decreasing oxygen supply to the nerve, and resulting in axonal degeneration.5 Another mechanism implicated in the pathogenesis of SICIN is the alteration in permeability of the sodium channel during development of the disease, and recent studies have demonstrated that the permeability of the voltage-dependent sodium channels is blocked
Neurological Research
2015
VOL .
37
NO .
9
797
Solmaz et al.
Demonstration of ameliorative effect of lacosamide: in a rat model
by the TNT-alpha released from the capillary endothelium during sepsis.6,7 Based on this, it may be suggested that any agent supressing the aforementioned inflammatory changes may be involved in development of SICIN. Lacosamide, i.e., R-2-acetamido-N-benzyl3-methoxypropionamide, is a newly developed antiepileptic.8 Literature shows studies of lacosamide on neuropathic pain; one study has demonstrated that vincristine-induced model of neuropathy has protective and disease-modifying characteristics,9 whereas another one has revealed positive effects of the agent on dorsal horn neuronal responses by modulating the sodium channels.10,11 However, no study has evaluated the effect of the agent on SICIN as well as its anti-inflammatory and neuroprotective characteristics. The aim of this study is to investigate the potential anti-inflammatory and lipid-peroxidation inhibiting activities of lacosamide by measuring TNF-alpha, C-reactive protein (CRP), malondialdehyde (MDA) and white blood cells (WBC) using electroneuromyography (ENMG) in rats with SICIN.
Materials and methods Animals In this study, 52 adult male albino Sprague Dawley rats weighing 200–250 g were used. Animals were fed ad libitum and housed in pairs in steel cages in a temperature-controlled environment (22 + 2uuC) of 12-h light/dark cycles. The experimental procedures were approved by the Animal Research Ethics Committee of the Gaziosmanpasa University (under approval no; 2013 HADYEK-30). All animal studies strictly conformed to The Animal Experiment Guidelines of the Committee for Animal Care.
Experimental procedures Rats were randomly assigned into five groups, and cecal ligation and puncture (CLP) procedure was performed on 39 rats to induce a sepsis model. Twelve rats died during the first 24 h following the surgical procedure, and they were excluded from the study. There was no mortality in the sham-operated group. The study groups were designed as follows: Group 1: normal (nonoperative and orally fed control, n58); Group 2: sham-operated (n58); Group 3: CLP (untreated group, n57); Group 4: CLP and lacosamide 20 mg/kg (Vimpat, UCB Pharma) intraperitoneal (i.p.) (n58); Group 5: CLP and lacosamide 40 mg/kg i.p. (n58). For the surgical procedure, rats were anesthetized by intraperitoneal injection of a combination of ketamine hydrochloride at a dose of 50 and 7 mg/kg xylazine hydrochloric (Alfazyne; Alfasan International BV, Woerden, Holland).
798
Neurological Research
2015
VOL .
37
NO .
9
Under aseptic conditions, a 3 cm midline laparotomy was performed to allow the exposure of the cecum with adjoining intestine. The cecum was ligated tightly with a 3.0 silk suture at its base under the iliocecal valve and punctured once with a 22-gauge needle. The cecum was then gently squeezed to extrude a small amount of feces from the perforation site. The cecum was returned to the peritoneal cavity, and the laparotomy incision was closed with a 4.0 polyglactin 910 suture. Following surgery, animals were allowed a recovery period, and then they were returned to their cages. In the sham group, under aseptic conditions, only laparotomy was performed on rats, but their cecum was neither ligated nor punctured. In this model, rats were considered septic 5 h following CLP.12 All treatments were performed during first hour of the surgical procedure.
Measurement of plasma TNF-alpha and CRP levels Plasma TNF-alpha and CRP levels were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kit (Biosciences). The plasma samples were diluted 1:2 and TNF-alpha and CRP levels were determined in duplicate according to the manufacturer’s instructions.
Measurement of lipid peroxidation Lipid peroxidation was determined in plasma samples by measuring MDA levels as thiobarbituric acid reactive substances. Briefly, trichloroacetic acid and TBARS reagent were added to the plasma samples, then mixed and incubated at 100uuC for 60 min. After cooling on ice, the samples were centrifuged at 3 000 rpm for 20 min, and the absorbance of the supernatant was read at 535 nm. MDA levels were expressed as nM, and tetraethoxypropane was used for calibration.
Peripheral Neutrophil Count Peripheral blood smears were stained with WrightGiemsa stain to evaluate the circulating neutrophils obtained at 24 h. Five high-power fields per slide (|200 magnification) were randomly selected, and the number of neutrophils per high power field was manually counted. A circulating neutrophil count was obtained by multiplying the average value by 1 000.
Electrophysiological recordings Electrophysiological recordings, electromyography (EMG) studies were performed 24 h after surgery. EMG was obtained three times from the right sciatic nerve and stimulated supramaximally (intensity 10 V, duration 0.05 ms, frequency 1 Hz, in the range of 0.5–5 000 Hz, 40 kHz/s with a sampling rate) using a Medelec Synergy (Oxford Instruments, Surrey, UK) bipolar stimulating electrode inserted subcutaneously
Solmaz et al.
at the sciatic notch. CMAPs were recorded from 2 to 3 interosseous muscles with unipolar platinum electrodes. Data were evaluated using Medelec-Oxford Synergy Quantitative EMG Test Software with distal latency and amplitude of the CMAP as the parameters. During the EMG recordings, rectal temperatures of the rats were monitored by a rectal probe (HP Viridia 24-C; Hewlett-Packard Company, Palo Alto, CA), and the temperature of each rat was kept at approximately 36–37uuC by a heating pad. Following EMG recordings, animals were euthanised, and blood samples were collected by cardiac puncture for biochemical measurements. They were centrifuged at 3 000 rpm for 10 min at room temperature and stored at ((20uuC until assay.
Statistical analysis Statistical evaluation was performed using SPSS version 15.0 for Windows. The Shapiro–Wilk test was used to see parametric and non-parametric distribution. All data were normally distributed, and thus parametric variables were compared using the Student’s t-test, Analysis of Variance with post hoc analysis using the Tuckey test. Results are presented as mean SEM. A Pv0.05 was accepted as statistically significant.
Results Evaluation of groups by the amplitude of CMAP When untreated sepsis group was compared with both control and sham-operated groups, CMAP amplitudes were significantly lower (Pv000.1), but no significant differences were found between the sham-operated group and the control group (Pw0.05). When CLP and CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, the CMAP amplitudes were significantly lower in the untreated CLP group (F514.67, Pv0.001). A post hoc analysis using the Tuckey test showed that both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups had better CMAP amplitudes only compared to the CLP group (Pv0.001 and Pv0001, respectively). However, no significant differences were found between CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg group (Pw0.05) (Table 1, Fig. 1).
Evaluation of groups by the latency of CMAP When untreated sepsis groups were compared with both control and sham-operated groups, latency
Demonstration of ameliorative effect of lacosamide: in a rat model
periods for CMAP were significantly lower (Pv000.1), but no significant differences were found between the sham-operated groups and the control groups (Pw0.05). When CLP and CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, the latency periods for CMAP were significantly lower in the untreated CLP groups (F518,23, Pv0.001). A post hoc analysis using the Tuckey test showed that both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups had better latency periods for CMAP only compared to the CLP groups (Pv0.001 and Pv001, respectively). When CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, latency periods for CMAP were better in favour of CLP plus lacosamide 40 mg/kg (Pv0.05) (Table 1, Fig. 1).
Evaluation of groups by the plasma levels of TNF-alpha There were no significant differences between the normal groups and the sham-operated groups in plasma levels of TNF-alpha (Pw0.05). When individually compared with the CLP groups, the TNFalpha levels were significantly higher than in both normal groups and sham-operated groups (Pv0.000, Pv0.0001). When CLP, CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha were significantly higher in the untreated CLP groups (F512.74, Pv0.0001). A post hoc analysis using the Tuckey test showed that plasma levels of TNF-alpha were lower in both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups only compared to the those in the CLP groups (Pv0.001 and Pv001, respectively). When CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha were better in favour of CLP plus lacosamide 40 mg/kg (Pv0.0001) (Table 2).
Evaluation of groups by plasma levels of MDA There were no significant differences between the normal groups and the sham-operated groups in plasma levels of MDA (Pw0.05). When individually compared with the CLP groups, plasma levels of MDA were significantly higher than in both normal groups and sham-operated groups (Pv0.001,
Table 1 Results were presented as + SEM
CMAP latency (ms) CMAP amplitude (mV)
Normal control (n58)
Sham operated (n58)
2.66+ 0.03 8.96+ 0.11
2.72+ 0.02 8.72+ 0.12
CLP (n57)
CLP and lacosamide 20 mg/kg (n58)
CLP and lacosamide 40 mg/kg (n58)
4.1+ 0.07** 4.4+ 0.29**
3.27+ 0.05# 6.82+ 0.18#
2.91+ 0.08## 7.14+ 0.25#
Pv0.0001, different from normal and sham-operated groups; #Pv0.001; ##Pv0.0001 different from CLP group.
**
Neurological Research
2015
VOL .
37
NO .
9
799
Solmaz et al.
Demonstration of ameliorative effect of lacosamide: in a rat model
Figure 1 Samples of CMAP recorded from (A) Normal group, (B) Sham group, (C) CLP group, (D) CLP and lacosamide 40 mg/kg. Table 2 Results were presented as + SEM
MDA (nM) TNF-alpha CRP (mg/dL) WBC/mL
Normal control (n58)
Sham operated (n58)
CLP (n57)
CLP and lacosamide 20 mg/kg (n58)
72.1+ 8.6 22.8+ 3.2 0.33+ 0.09 4.1+ 0.5
98.3+ 10.6 24.9+ 1.2 0.49+ 0.11 4.4+ 0.3
182.4+ 13.9* 254.2+ 11.4{ 0.84+ 0.16** 9.8+ 1.1**
148.6+ 13.1# 186.4+ 10.3{ 0.76+ 0.23 9.5+ 1.05
*Pv0.001; **Pv0.05; {Pv0.000, different from normal and sham-operated groups; #Pv0.05, CLP group.
Pv0.001). When CLP, CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, plasma levels of MDA were significantly higher in the untreated CLP groups (F519.43, Pv0.05). A post hoc analysis using the Tuckey test showed that plasma levels of MDA were lower in both CLP plus lacosamide 20 mg/kg and CLP plus lacosamide40 mg/kg groups only compared to the those in the CLP groups (Pv0.05 and Pv001, respectively). When CLP plus lacosamide 20 mg/kg and CLP plus lacosamide 40 mg/kg groups were compared, no significant difference was observed in plasma levels of MDA between the tow groups (Pw0.05) (Table 2).
Evaluation of groups by plasma levels of CRP and WBC A comparison of CRP and WBC counts between the normal groups and sham-operated groups showed that the difference was not statistically significant (Pw0.05); however, when untreated CRP group was compared indiviually with the control and shamoperated groups, CRP and WBC levels were
800
Neurological Research
2015
VOL .
37
NO .
9
CLP and lacosamide 40 mg/kg (n58) 115.8+ 9.5## 152.4+ 9.6{ 0.45+ 0.17## 9.2+ 1.6
##
Pv0.001; {Pv0.000 different from
significantly higher (Pv0.05). A comparison among CLP and CLP plus lacosamide 20 mg/kg, CLP plus lacosamide 40 mg/kg groups showed a significant difference in plasma levels of WBC and CRP (F518.35, Pv0.001). A post hoc analysis using the Tukey test showed no significant difference in WBC and CRP levels in the CLP plus lacosamide 20 mg/kg group compared to the untreated CLP group (Pw0.05); however in the CLP plus lacosamide 40 mg/kg group, CRP levels were significantly lower only compared to the CLP group (Pv0.001), and no significant difference was found in WBC levels (Pw0.05) (Table 2).
Discussion Despite many studies, CIN remains a major cause of morbidity and mortality in the intensive care, and its exact pathogenesis is still unclear.2 The condition is usually diagnosed with clinical and electroneuromyographic methods. Reduced CMAP amplitudes, which is a sign of axonal damage as shown by ENMG, are critical for diagnosis of the disease.13 Accordingly, in our study, ENMG showed significant reductions in CMAP amplitudes in the sepsis-induced groups
Solmaz et al.
compared to the control group, but CMAP amplitudes were significantly better in both dosages of lacosamide 20 and 40 mg/kg; however, the effect of lacosamide was not dose-dependent (no significant differences between 20 and 40 mg/kg). To the best of authors’ knowledge, in the literature there is no study which evaluated anti-inflammatory and lipid peroxidation inhibiting activities of lacosamide in early SICIN. During sepsis, elevated levels of cytokines including TNF-alpha, heat shock proteins, free oxygen radicals and fat acid metabolites are suggested to have an impact on the microvascular circulation, resulting in impaired supply to the nerve and axonal degeneration.14 According to this, it is possible to propose that any agent inhibiting such events induced by sepsis may have beneficial effects on SICIN. A study on the effects of melatonin and oxytocin on the CIN showed that both oxytocin and melatonin reduced TNF-alpha, leading to anti-inflammatory effects and suppressed oxidative stress, displaying antioxidative effects.15 Similarly, in this study, plasma levels of TNF-alpha WBC and CRP are significantly higher in the CLP group than both in control and sham-operated groups, and furthermore levels of MDA, a product of lipid peroxidation, are higher in the CLP group. The inflammatory markers and MDA levels are significantly reduced in the CLP group receiving lacosamide, which suggests that anti-inflammatory and lipid peroxidation inhibiting activities of lacosamide may be beneficial in SICIN. Kevin et al. indicated that acquired sodium channelopathy may be involved in the pathogenesis of CIN, and reported that voltage-dependent sodium channels were blocked by TNF-alpha, reducing excitability of the nerve,7 and a similar study proposed that TNF-alpha may be involved in the pathogenesis of critical illness polyneuropathy through activation of protein kinase C, and downregulation of the sodium channels in skeletal muscles.6 In this study, reduced plasma levels of TNF-alpha in the sepsis groups receiving lacozamide suggest that TNF-alpha might have inhibited these potential effects displaying beneficial effects on SICIN. A study by Bee and Dickenson reported the effects of lacosamide on dorsal horn neuronal responses through modulation of sodium channels in a rat model of neuropathy,10 and the sodium channel modulating effects of this agent were reported by other studies.11,16 Another mechanism implicated in the pathogenesis of SICIN is the disruption of vascular permeability by releasing of inflammatory cytokines and Na-K pump dysfunction secondary to it so that resting membrane potential does not return to the normal level.17 Accordingly, lacosamide, which was reported to have sodium channel modulatory effects by previous studies, might have beneficial effects on SICIN by modulating the
Demonstration of ameliorative effect of lacosamide: in a rat model
disrupted Na-K pump, and as a matter of fact, positive effects of levetiracetam, another antiepileptic which is considered to have a similar mechanism, have been reported in SICIN.18 In another study, Bettina et al. reported that lacosamide was very effective in myalgia induced by TNFalpha in a rat model, even had a better analgesic effect than pregabalin and gabapentin when administered at a dose of 30 mg/kg.19 Although levels of TNF-alpha were not measured in the aforementioned study, a question may arise to whether the agent showed its analgesic effects through reduction of TNF-alpha levels, considering the results of our study. As a result of a literature review, the authors believe that this study is important as it is the first study which has evaluated the effects of lacosamide on CIN; however, the underlying mechanism of this agent remains unclear. One major limitation of our study was a failure to study the effects of lacosamide on sodium channels. In conclusion, we showed that lacosamide may have beneficial effects on early SICIN by its potential anti-inflammatory and lipid peroxidation inhibiting activities. However, further comprehensive studies are required to clarify how these effects occur and also chronic effects of lacosamide in SICIN.
Disclaimer Statements Contributors Volkan Solmaz: study design, writing, experimental procedure. Durdane Aksoy: writing, literature screening. Mustafa Yılmaz: editing, writing. Enes Eser: experimental procedure. Oytun Erbas: study design, writing, experimental procedure. Funding None. Conflicts of interest The authors declarers that there is no conflict of interests. Ethics approval Our manuscript has been under approval (no; 2013 HADYEK-30).
References 1 Bolton CF. Neuromuscular manifestations of critical illness. Muscle Nerve. 2005;32(2):140–63. 2 Stevens RD, Dowdy DW, Michaels RK, Mendez-Tellez PA, Pronovost PJ, Needham DM. Neuromuscular dysfunction acquired in critical illness: a systematic review. Intensive Care Med. 2007;33(11):1876–91. 3 Zochodne DW, Bolton CF, Wells GA, Gilbert JJ, Hahn AF, Brown JD, et al. Critical illness polyneuropathy. A complication of sepsis and multiple organ failure. Brain. 1987;110(Pt 4):819–41. 4 Tennila A, Salmi T, Pettila V, Roine RO, Varpula T, Takkunen O. Early signs of critical illness polyneuropathy in ICU patients with systemic inflammatory response syndrome or sepsis. Intensive Care Med. 2000;26(9):1360–3. 5 Hermans G, De Jonghe B, Bruyninckx F, Van den Berghe G. Clinical review: critical illness polyneuropathy and myopathy. Crit Care. 2008;12(6):238. 6 Guillouet M, Gueret G, Rannou F, Giroux-Metges MA, Gioux M, Arvieux CC, et al. Tumor necrosis factor-downregulates sodium current in skeletal muscle by protein kinase C activation: involvement in critical illness polyneuromyopathy. Am J Physiol Cell Physiol. 2011;301:1057–63.
Neurological Research
2015
VOL .
37
NO .
9
801
Solmaz et al.
Demonstration of ameliorative effect of lacosamide: in a rat model
7 Novak KR, Nardelli P, Cope TC, Filatov G, Glass JD, Khan J, et al. Inactivation of sodium channels underlies reversible neuropathy during critical illness in rats. J Clin Invest. 2009;119(5): 1150–8. 8 Hao JX, Stohr T, Selve N, Wiesenfeld-Hallin Z, Xu XJ. Lacosamide, a new anti-epileptic, alleviates neuropathic pain-like behaviors in rat models of spinal cord or trigeminal nerve injury. Eur J Pharmacol. 2006;553(1–3):135–40. 9 Geis C, Beyreuther BK, Stohr T, Sommer C. Lacosamide has protective disease modifying properties in experimental vincristine neuropathy. Neuropharmacology. 2011;61(4):600–7. 10 Bee LA, Dickenson AH. Effects of lacosamide, a novel sodium channel modulator, on dorsal horn neuronal responses in a rat model of neuropathy. Neuropharmacology. 2009;57(4):472–9. 11 Sheets PL, Heers C, Stoehr T, Cummins TR. Differential block of sensory neuronal voltage-gated sodium channels by lacosamide [(2R)-2-(acetylamino)-N-benzyl-3-methoxypropanamide], lidocaine, and carbamazepine. J Pharmacol Exp Ther. 2008; 326(1):89–99. 12 Iseri SO, Sener G, Saglam B, Gedik N, Ercan F, Yegen BC. Oxytocin protects against sepsis-induced multiple organ damage: role of neutrophils. J Surg Res. 2005;126(1):73–81. 13 Farivar BS, Eiref SD, Leitman IM. Strategies to prevent sepsisinduced intensive care uniteacquired weakness: are there any
802
Neurological Research
2015
VOL .
37
NO .
9
14 15
16
17 18
19
options? Commentary on ‘‘Comparison of melatonin and oxytocin in the prevention of critical illness polyneuropathy in rats with surgically induced sepsis’’. J Surg Res. 2013;185:39–42. Leitman IM. Modulating the inflammatory response in sepsis. J Surg Res. 2011;171(2):e183–5. ¨ , Taskiran D. Erbas O, Ergenoglu AM, Akdemir A, Yeniel AO Comparison of melatonin and oxytocin in the prevention of critical illness polyneuropathy in rats with experimentallyinduced sepsis. J Surg Res. 2013;183(1):313–20. Errington AC, Stohr T, Heers C, Lees G. The investigational anticonvulsant lacosamide selectively enhances slow inactivation of voltage-gated sodium channels. Mol Pharmacol. 2008;73(1): 157–69. Fang C, Bourdette D, Banker G. Oxidative stress inhibits axonal transport: implications for neurodegenerative diseases. Mol Neurodegener. 2012;7:29. Erbas O, Yeniel AO, Akdemir A, Ergenoglu AM, Yilmaz M, Taskiran D, et al. The beneficial effects of levetiracetam on polyneuropathy in the early stage of sepsis in rats: electrophysiological and biochemical evidence. J Invest Surg. 2013; 26(6):312–8. Beyreuther BK, Geis C, Stohr T, Sommer C. Antihyperalgesic efficacy of lacosamide in a rat model for muscle pain induced by TNF. Neuropharmacology. 2007;52(5):1312–7.
![[Critical illness polyneuropathy and myopathy as neurological complications of sepsis].](/assets/img/hold.png)
