J Med Primatol doi:10.1111/jmp.12128
ORIGINAL ARTICLE
The effect of propofol on intravenous glucose tolerance test in rhesus monkey Jong Min Kim1,2,3,†, Jun-Seop Shin1,2,3,†, Il Hee Yoon1,2,4, Byoung Hoon Min1,2, Won Young Jeong1, Ga Eul Lee1, Min Sun Kim1, Ju Eun Kim1, Jae Yool Jang1 & Chung-Gyu Park1,2,3,4,5 1 2 3 4 5
Translational Xenotransplantation Research Center, Seoul, Korea Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Korea Medical Research Institute for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
Keywords cortisol – insulin secretion – intravenous glucose tolerance test – propofol – rhesus monkey Correspondence Chung-Gyu Park, Department of Microbiology and Immunology, Translational Xenotransplantation Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, 110-799 Seoul, Korea. Tel.: +82 2 740 8007, 8308; fax: +82 2 743 0881; e-mail: [email protected] † These two authors contributed equally to this work.
Accepted April 11, 2014.
Abstract Background Many anesthetics have been shown to impair glucose metabolism and cause hyperglycemia. The aim of this study was to evaluate the effects of propofol on glucose metabolism and insulin secretion during intravenous glucose tolerance test (IVGTT) in rhesus monkey. Methods Serum cortisol, blood glucose, insulin, and C-peptide concentrations during IVGTT were measured in four rhesus monkeys under either conscious state or propofol anesthesia. Results and Conclusions The levels of serum cortisol significantly increased under conscious condition, whereas these levels remained constant under propofol anesthesia. In propofol group, the levels of serum insulin and C-peptide significantly increased compared with those in conscious group. Accordingly, glucose disposal capacity was significantly improved, and the time to return to basal glucose levels was shortened in propofol group. This study showed that propofol significantly increased insulin and C-peptide, and the corresponding improvement in glucose disposal may be related to reduction of serum cortisol in monkey.
Introduction The intravenous glucose tolerance test (IVGTT) is an assessment of the first-phase insulin response to glucose for diagnosing glucose intolerance or overt diabetes in humans [1]. The IVGTT has also been widely used to measure islet function in preclinical studies such as pig-to-monkey islet xenotransplantation and other rodent experiments using diabetic animals [3, 5]. However, the test mostly performed under conscious state can induce physical and psychological stresses, which may negatively affect glucose metabolism, thereby generating unpredictable data associated with systemic stress. To alleviate stress-induced abnormal glucose metabolism and/or insulin secretion, 242
anesthetics may be incorporated during IVGTT procedure. Unfortunately, many anesthetics widely used in both clinic and animal studies including medetomidine, diazepam, ketamine, and isoflurane have been shown to impair glucose metabolism, and in most cases, they cause hyperglycemia [6, 8, 10, 11]. However, propofol has been reported to provide stable glucose homeostasis during anesthesia without significant effects on glucose metabolism in rodents [9]. In this study, we aim to evaluate the effects of propofol on serum cortisol, blood glucose, insulin, and C-peptide concentrations during IVGTT in rhesus monkey. Also, the mean arterial pressure, heart rate, and body temperature were also compared between under conscious state and propofol anesthesia. J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Effect of propofol on IVGTT in rhesus monkey
Kim et al.
Materials and methods
Czech) levels were determined by an immunoradiometric assay according to the manufacturer’s instructions.
Experimental animals Four healthy 4–5-year-old male adult rhesus monkeys weighing 5.0–6.8 kg were used in this study. Each of the four monkeys underwent IVGTT in conscious state, and then, same monkeys underwent IVGTT under propofol anesthesia 1 week later. During IVGTT, the monkey was placed in monkey chair. Anesthesia was induced with propofol (2 mg/kg, i.v.). Continuous intravenous infusion of propofol (0.2 mg/kg/minute) was then administered [4]. The animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of the Biomedical Research Institute at the Seoul National University Hospital (AAALAC-accredited facility; IACUC number: 12-0374). IVGTT, hemodynamic variables, and BT monitoring After the monkeys were positioned and then conscious state of each monkey was achieved, 22 gage intravenous catheters were positioned in both saphenous veins. Ten minutes after initiation of propofol, a solution of 0.5 g of glucose per kg of body weight was administered into the right saphenous vein. Two milliliters of blood was collected from the left saphenous vein at the baseline, immediately before administration of glucose, and 2, 5, 15, 30, 60, 90, and 120 minutes after administration of glucose for measuring blood glucose, serum cortisol, insulin, and C-peptide. Blood glucose concentrations were measured using a small electrode-type blood glucose meter (Accu-ChekTM; Roche Diagnostics, Seoul, Korea). Non-invasive mean arterial blood pressure, heart rate, and body temperature using patient monitor (Infinity Delta; Dr€ ager, Telford, PA, USA) were monitored before and at 30, 60, 90, and 120 minutes after administration of glucose.
Glucose disappearance rate The glucose disappearance rate (KG) represents the loglinear (ln) decline in glucose level between 15 and 30 minutes of IVGTT and was calculated using the following formula: KG = ln (glucose level at 15 minutes) ln (glucose level at 30 minutes)/15 9 100 Statistical analysis All results were expressed as mean standard deviation (SD) and were analyzed by one-way repeated measures analysis of variance (ANOVA) using SPSS version 13.0 for Windows (SPSS Inc., Chicago, IL, USA). A P value < 0.05 was considered statistically significant. Results Measurement of serum cortisol In the conscious group, the levels of serum cortisol significantly increased from 32.7 at the basal state to 53.3 lg/dl at 120 minutes after performing IVGTT (P < 0.05); however, under propofol anesthesia, the levels slightly decreased and remained stable around 25–30 lg/dl throughout IVGTT (Fig. 1). These results strongly suggested that conducting IVGTT in the conscious condition caused systemic stress, but propofol effectively relieved this stress. Consistent with this notion, the monkeys in the conscious condition moved around on the chair and their hands or feet frequently moved back and forth during IVGTT, but under propofol anesthesia, they were sitting quietly throughout the
Measurements of cortisol, insulin, and C-peptide in serum For measuring serum cortisol, insulin, and C-peptide concentrations, blood samples were collected in a serum-separating tube. Blood samples were centrifuged at 2990 g for 20 minutes at 4°C, and the separated serum was stored at 80°C until further use. Serum cortisol levels were determined by a chemiluminescent immunoassay (ADVIA CentaurTM Cortisol Lite Reagent & Solid Phase; Siemens, Tarrytown, NY, USA) according to the manufacturer’s instructions. Serum insulin (Insulin IRMA Kit; Biosource, Nivelles, Belgium) and C-peptide (C-peptide IRMA Kit; Immunotech, Prague, J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Fig. 1 The levels of cortisol in serum during IVGTT under the conscious or propofol anesthesia condition. *P < 0.05 vs. propofol sedation.
243
Effect of propofol on IVGTT in rhesus monkey
experiment (Supplementary video, which is freely available in http://blog.naver.com/ohbosle/100207143650). Measurement of blood glucose, insulin, and C-peptide levels Blood glucose levels after glucose bolus increased and then normalized within 2 hours in both conscious and propofol anesthesia groups, but normalization pattern in propofol group seemed to be faster than in conscious group (Fig. 2). Indeed, KG values between 15 and 30 minutes were 1.71 0.51 in the conscious group and 3.87 1.39 in the propofol anesthesia group. This difference was statistically significant (P = 0.02). The time to return to basal blood glucose levels in propofol group
Kim et al.
tended to be shorter than that in conscious group (59.2 34.8 and 49.9 46.8 minutes in conscious and propofol group, respectively), although this difference was not significant due to large individual variations. Consistent with these data, the levels of serum insulin and C-peptide in the propofol group tended to be augmented and indeed C-peptide values at early time points (15 and 30 minutes) in this group were statistically significant compared with those observed in the conscious group (P < 0.05, Fig. 3). Hemodynamic variables and body temperature Mean arterial pressure and heart rate were significantly lower in propofol anesthesia condition than in conscious condition (P < 0.05). Body temperature was slightly lower in propofol anesthesia than in conscious condition, but it did not reach statistical significance (Fig. 4). Discussion
Fig. 2 Blood glucose levels during IVGTT under conscious (-○-) or propofol anesthesia condition (-□-). Each of the four monkeys underwent IVGTT in conscious state, and then, same monkeys underwent IVGTT under propofol sedation 1 week later. In the conscious group, a solution of 0.5 g of glucose per kg of body weight was administered into the right saphenous vein. Two milliliters of blood was collected from the left saphenous vein at baseline, immediately before administration of glucose, and 2, 5, 15, 30, 60, 90, and 120 minutes after administration of glucose for measuring blood glucose. In the propofol group, propofol was given ten minutes before injecting glucose bolus.
The IVGTT is relatively non-invasive, but the restraint of the monkeys on the chair during IVGTT is an uncomfortable procedure that can initiate physical distress due to discomfort, embarrassment, and/or pain induced by saphenous catheterization. Furthermore, these behavioral responses of the monkeys inevitably induce systemic stress and may affect glucose tolerance variables during IVGTT. To relieve this stress, in this study, propofol was administered to the monkeys prior to injection of glucose bolus. This simple procedure clearly relieved monkey from stress as revealed by significantly decreased cortisol levels (53.3 vs. 30 lg/dl in conscious vs. propofol anesthesia, respectively, P < 0.05) and quiet behavior throughout the experiment in the propofol group (Fig. 2 and Supplementary video). Although it remains unclear whether decreased cortisol levels are directly correlated with the extent of stress
Fig. 3 The levels of C-peptide and insulin in serum during IVGTT under the conscious or propofol anesthesia condition. *P < 0.05 vs. propofol sedation.
244
J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Kim et al.
Effect of propofol on IVGTT in rhesus monkey
Fig. 4 Hemodynamic variables [mean arterial pressure (MAP), heart rate (HR), and body temperature (BT)] during IVGTT under conscious or propofol anesthesia condition. *P < 0.05 vs. propofol sedation.
relief in the monkeys, our behavioral observation supports our hypothesis. In addition, cortisol has been frequently used in various experimental settings as an objective marker when evaluating psychological and laboratory stresses [12, 13]. Increased serum cortisol concentration in conscious state led us to hypothesize that the first-phase insulin secretion may be inhibited by cortisol, and glucose disposal capacity is expected to be reduced. Indeed, the blood glucose pattern in conscious group seems to be grossly normal, but our estimation of KG between 15 and 30 minutes after glucose bolus can differentiate marginal but significant decrease in the glucose disappearance rate compared with propofol group. The time to return to basal level in conscious group also tended to be longer than in propofol group. Moreover, insulin and C-peptide concentration in conscious group where serum cortisol levels remained higher during IVGTT showed significant decreases compared with those in propofol group (Fig. 3). Collectively, our results suggest that propofol not only relieved physical stress during IVGTT procedure, but also increased insulin secretion and enhanced glucose tolerance in monkeys. In support of this notion, chronic glucocorticoid therapy and the syndrome of cortisol excess are associated with increased glucose concentration, glucose intolerance, and diabetes by several mechanisms including suppression of insulin secretion from pancreatic b-cells [14]. To date, there are some studies that have examined the effects of different anesthetic agents on glucose tolerance variables during IVGTT. Kamine et al. [8] have examined the effects of tiletamine and zolazepam and/or medetomidine on glucose tolerance in captive Japanese black bears and found that medetomidine but not zolazepam caused hyperglycemia. Several reports also showed that ketamine and diazepam caused hyperglycemia in rabbits and baboons [6, 10]. By contrast, Ionut J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
et al. [7] reported that a prior administration of acepromazine during IVGTT did not interfere with glucose metabolism in dogs. Kitamura et al. [9] showed that sevoflurane caused severe hyperglycemia during sigmoid colostomy, but propofol did not affect blood glucose levels in rats. Collectively, these results suggested that if suitable doses and/or classes of anesthetic agents were used, the anesthesia-induced blood glucose disturbance can be minimized with keeping normal physiological responses. Unfortunately, this study by using propofol did not achieve this primary goal, but instead found IVGTT in conscious state can induce systemic stress reflected by increase of serum cortisol, thereby leading to mild glucose intolerance. There are several limitations in the present study. First, the number of animals is too small (n = 4) to obtain more convincing data with strong statistical power, although some data such as KG and C-peptide reached statistical significance. If more animals will be used in the future study, clearer conclusion will be made. Second, only single anesthetic agent was used. Although the concern about the increased risk of seizure by using phenothiazine in humans made us to choose propofol as a primary agent [2], the applicability of other anesthetic agents such as acepromazine needs further study. In summary, the results of this study demonstrated that propofol not only relieved physical stress, but enhanced glucose tolerance by increasing insulin and C-peptide secretion in monkeys. Acknowledgments This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health &Welfare, Republic of Korea (grant number: HI13C0954). 245
Effect of propofol on IVGTT in rhesus monkey
Kim et al.
References 1 Bingley PJ, Colman P, Eisenbarth GS, Jackson RA, McCulloch DK, Riley WJ, Gale EA: Standardization of IVGTT to predict IDDM. Diabetes Care 1992; 15:1313–6. 2 Drynan EA, Gray P, Raisis AL: Incidence of seizures associated with the use of acepromazine in dogs undergoing myelography. J Vet Emerg Crit Care (San Antonio) 2012; 22:262–6. 3 Dufrane D, Maillart JF, Aouassar N, Goebbels RM, Guiot Y, Gianello P: Native pancreatic alpha-cell adaptation in streptozotocin-induced diabetic primates: importance for pig islet xenotransplantation. Xenotransplantation 2009; 16:152–63. 4 Fanton JW, Zarr SR, Ewert DL, Woods RW, Koenig SC: Cardiovascular responses to propofol and etomidate in long-term instrumented rhesus monkeys (Macaca mulatta). Comp Med 2000; 50: 303–8. 5 Furuya H, Kimura T, Murakami M, Katayama K, Hirose K, Yamaguchi A: Revascularization and function of pancreatic islet isografts in diabetic rats following transplan-
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tation. Cell Transplant 2003; 12:537–44. Illera JC, Gonzalez Gil A, Silvan G, Illera M: The effects of different anaesthetic treatments on the adreno-cortical functions and glucose levels in NZW rabbits. J Physiol Biochem 2000; 56:329–36. Ionut V, Kirkman EL, Bergman RN: Investigation of the effect of acepromazine on intravenous glucose tolerance tests in dogs. Am J Vet Res 2004; 65:1124–7. Kamine A, Shimozuru M, Shibata H, Tsubota T: Effects of intramuscular administration of tiletamine-zolazepam with and without sedative pretreatment on plasma and serum biochemical values and glucose tolerance test results in Japanese black bears (Ursus thibetanus japonicus). Am J Vet Res 2012; 73:1282–9. Kitamura T, Ogawa M, Kawamura G, Sato K, Yamada Y: The effects of sevoflurane and propofol on glucose metabolism under aerobic conditions in fed rats. Anesth Analg 2009; 109:1479–85. Lehmann R, Wagner JL, Fernandez LA, Bourgoignie JJ, Ricordi C,
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Alejandro R, Kenyon NS: Effects of ketamine sedation on glucose clearance, insulin secretion and counterregulatory hormone production in baboons (Papio hamadryas). J Med Primatol 1997; 26:312–21. Tanaka T, Nabatame H, Tanifuji Y: Insulin secretion and glucose utilization are impaired under general anesthesia with sevoflurane as well as isoflurane in a concentration-independent manner. J Anesth 2005; 19:277–81. Willemse T, Vroom MW, Mol JA, Rijnberk A: Changes in plasma cortisol, corticotropin, and alpha-melanocyte-stimulating hormone concentrations in cats before and after physical restraint and intradermal testing. Am J Vet Res 1993; 54:69–72. Yoder B, Wolf JS Jr: Canine model of surgical stress response comparing standard laparoscopic, microlaparoscopic, and hand-assisted laparoscopic nephrectomy. Urology 2005; 65:600–3. Andrews RC, Walker BR: Glucocorticoids and insulin resistance: old hormones, new targets. Clin Sci (Lond) 1999; 96:513–23.
J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
ORIGINAL ARTICLE
The effect of propofol on intravenous glucose tolerance test in rhesus monkey Jong Min Kim1,2,3,†, Jun-Seop Shin1,2,3,†, Il Hee Yoon1,2,4, Byoung Hoon Min1,2, Won Young Jeong1, Ga Eul Lee1, Min Sun Kim1, Ju Eun Kim1, Jae Yool Jang1 & Chung-Gyu Park1,2,3,4,5 1 2 3 4 5
Translational Xenotransplantation Research Center, Seoul, Korea Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Korea Medical Research Institute for Infectious Diseases, Seoul National University College of Medicine, Seoul, Korea Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea
Keywords cortisol – insulin secretion – intravenous glucose tolerance test – propofol – rhesus monkey Correspondence Chung-Gyu Park, Department of Microbiology and Immunology, Translational Xenotransplantation Research Center, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, 110-799 Seoul, Korea. Tel.: +82 2 740 8007, 8308; fax: +82 2 743 0881; e-mail: [email protected] † These two authors contributed equally to this work.
Accepted April 11, 2014.
Abstract Background Many anesthetics have been shown to impair glucose metabolism and cause hyperglycemia. The aim of this study was to evaluate the effects of propofol on glucose metabolism and insulin secretion during intravenous glucose tolerance test (IVGTT) in rhesus monkey. Methods Serum cortisol, blood glucose, insulin, and C-peptide concentrations during IVGTT were measured in four rhesus monkeys under either conscious state or propofol anesthesia. Results and Conclusions The levels of serum cortisol significantly increased under conscious condition, whereas these levels remained constant under propofol anesthesia. In propofol group, the levels of serum insulin and C-peptide significantly increased compared with those in conscious group. Accordingly, glucose disposal capacity was significantly improved, and the time to return to basal glucose levels was shortened in propofol group. This study showed that propofol significantly increased insulin and C-peptide, and the corresponding improvement in glucose disposal may be related to reduction of serum cortisol in monkey.
Introduction The intravenous glucose tolerance test (IVGTT) is an assessment of the first-phase insulin response to glucose for diagnosing glucose intolerance or overt diabetes in humans [1]. The IVGTT has also been widely used to measure islet function in preclinical studies such as pig-to-monkey islet xenotransplantation and other rodent experiments using diabetic animals [3, 5]. However, the test mostly performed under conscious state can induce physical and psychological stresses, which may negatively affect glucose metabolism, thereby generating unpredictable data associated with systemic stress. To alleviate stress-induced abnormal glucose metabolism and/or insulin secretion, 242
anesthetics may be incorporated during IVGTT procedure. Unfortunately, many anesthetics widely used in both clinic and animal studies including medetomidine, diazepam, ketamine, and isoflurane have been shown to impair glucose metabolism, and in most cases, they cause hyperglycemia [6, 8, 10, 11]. However, propofol has been reported to provide stable glucose homeostasis during anesthesia without significant effects on glucose metabolism in rodents [9]. In this study, we aim to evaluate the effects of propofol on serum cortisol, blood glucose, insulin, and C-peptide concentrations during IVGTT in rhesus monkey. Also, the mean arterial pressure, heart rate, and body temperature were also compared between under conscious state and propofol anesthesia. J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Effect of propofol on IVGTT in rhesus monkey
Kim et al.
Materials and methods
Czech) levels were determined by an immunoradiometric assay according to the manufacturer’s instructions.
Experimental animals Four healthy 4–5-year-old male adult rhesus monkeys weighing 5.0–6.8 kg were used in this study. Each of the four monkeys underwent IVGTT in conscious state, and then, same monkeys underwent IVGTT under propofol anesthesia 1 week later. During IVGTT, the monkey was placed in monkey chair. Anesthesia was induced with propofol (2 mg/kg, i.v.). Continuous intravenous infusion of propofol (0.2 mg/kg/minute) was then administered [4]. The animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of the Biomedical Research Institute at the Seoul National University Hospital (AAALAC-accredited facility; IACUC number: 12-0374). IVGTT, hemodynamic variables, and BT monitoring After the monkeys were positioned and then conscious state of each monkey was achieved, 22 gage intravenous catheters were positioned in both saphenous veins. Ten minutes after initiation of propofol, a solution of 0.5 g of glucose per kg of body weight was administered into the right saphenous vein. Two milliliters of blood was collected from the left saphenous vein at the baseline, immediately before administration of glucose, and 2, 5, 15, 30, 60, 90, and 120 minutes after administration of glucose for measuring blood glucose, serum cortisol, insulin, and C-peptide. Blood glucose concentrations were measured using a small electrode-type blood glucose meter (Accu-ChekTM; Roche Diagnostics, Seoul, Korea). Non-invasive mean arterial blood pressure, heart rate, and body temperature using patient monitor (Infinity Delta; Dr€ ager, Telford, PA, USA) were monitored before and at 30, 60, 90, and 120 minutes after administration of glucose.
Glucose disappearance rate The glucose disappearance rate (KG) represents the loglinear (ln) decline in glucose level between 15 and 30 minutes of IVGTT and was calculated using the following formula: KG = ln (glucose level at 15 minutes) ln (glucose level at 30 minutes)/15 9 100 Statistical analysis All results were expressed as mean standard deviation (SD) and were analyzed by one-way repeated measures analysis of variance (ANOVA) using SPSS version 13.0 for Windows (SPSS Inc., Chicago, IL, USA). A P value < 0.05 was considered statistically significant. Results Measurement of serum cortisol In the conscious group, the levels of serum cortisol significantly increased from 32.7 at the basal state to 53.3 lg/dl at 120 minutes after performing IVGTT (P < 0.05); however, under propofol anesthesia, the levels slightly decreased and remained stable around 25–30 lg/dl throughout IVGTT (Fig. 1). These results strongly suggested that conducting IVGTT in the conscious condition caused systemic stress, but propofol effectively relieved this stress. Consistent with this notion, the monkeys in the conscious condition moved around on the chair and their hands or feet frequently moved back and forth during IVGTT, but under propofol anesthesia, they were sitting quietly throughout the
Measurements of cortisol, insulin, and C-peptide in serum For measuring serum cortisol, insulin, and C-peptide concentrations, blood samples were collected in a serum-separating tube. Blood samples were centrifuged at 2990 g for 20 minutes at 4°C, and the separated serum was stored at 80°C until further use. Serum cortisol levels were determined by a chemiluminescent immunoassay (ADVIA CentaurTM Cortisol Lite Reagent & Solid Phase; Siemens, Tarrytown, NY, USA) according to the manufacturer’s instructions. Serum insulin (Insulin IRMA Kit; Biosource, Nivelles, Belgium) and C-peptide (C-peptide IRMA Kit; Immunotech, Prague, J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Fig. 1 The levels of cortisol in serum during IVGTT under the conscious or propofol anesthesia condition. *P < 0.05 vs. propofol sedation.
243
Effect of propofol on IVGTT in rhesus monkey
experiment (Supplementary video, which is freely available in http://blog.naver.com/ohbosle/100207143650). Measurement of blood glucose, insulin, and C-peptide levels Blood glucose levels after glucose bolus increased and then normalized within 2 hours in both conscious and propofol anesthesia groups, but normalization pattern in propofol group seemed to be faster than in conscious group (Fig. 2). Indeed, KG values between 15 and 30 minutes were 1.71 0.51 in the conscious group and 3.87 1.39 in the propofol anesthesia group. This difference was statistically significant (P = 0.02). The time to return to basal blood glucose levels in propofol group
Kim et al.
tended to be shorter than that in conscious group (59.2 34.8 and 49.9 46.8 minutes in conscious and propofol group, respectively), although this difference was not significant due to large individual variations. Consistent with these data, the levels of serum insulin and C-peptide in the propofol group tended to be augmented and indeed C-peptide values at early time points (15 and 30 minutes) in this group were statistically significant compared with those observed in the conscious group (P < 0.05, Fig. 3). Hemodynamic variables and body temperature Mean arterial pressure and heart rate were significantly lower in propofol anesthesia condition than in conscious condition (P < 0.05). Body temperature was slightly lower in propofol anesthesia than in conscious condition, but it did not reach statistical significance (Fig. 4). Discussion
Fig. 2 Blood glucose levels during IVGTT under conscious (-○-) or propofol anesthesia condition (-□-). Each of the four monkeys underwent IVGTT in conscious state, and then, same monkeys underwent IVGTT under propofol sedation 1 week later. In the conscious group, a solution of 0.5 g of glucose per kg of body weight was administered into the right saphenous vein. Two milliliters of blood was collected from the left saphenous vein at baseline, immediately before administration of glucose, and 2, 5, 15, 30, 60, 90, and 120 minutes after administration of glucose for measuring blood glucose. In the propofol group, propofol was given ten minutes before injecting glucose bolus.
The IVGTT is relatively non-invasive, but the restraint of the monkeys on the chair during IVGTT is an uncomfortable procedure that can initiate physical distress due to discomfort, embarrassment, and/or pain induced by saphenous catheterization. Furthermore, these behavioral responses of the monkeys inevitably induce systemic stress and may affect glucose tolerance variables during IVGTT. To relieve this stress, in this study, propofol was administered to the monkeys prior to injection of glucose bolus. This simple procedure clearly relieved monkey from stress as revealed by significantly decreased cortisol levels (53.3 vs. 30 lg/dl in conscious vs. propofol anesthesia, respectively, P < 0.05) and quiet behavior throughout the experiment in the propofol group (Fig. 2 and Supplementary video). Although it remains unclear whether decreased cortisol levels are directly correlated with the extent of stress
Fig. 3 The levels of C-peptide and insulin in serum during IVGTT under the conscious or propofol anesthesia condition. *P < 0.05 vs. propofol sedation.
244
J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Kim et al.
Effect of propofol on IVGTT in rhesus monkey
Fig. 4 Hemodynamic variables [mean arterial pressure (MAP), heart rate (HR), and body temperature (BT)] during IVGTT under conscious or propofol anesthesia condition. *P < 0.05 vs. propofol sedation.
relief in the monkeys, our behavioral observation supports our hypothesis. In addition, cortisol has been frequently used in various experimental settings as an objective marker when evaluating psychological and laboratory stresses [12, 13]. Increased serum cortisol concentration in conscious state led us to hypothesize that the first-phase insulin secretion may be inhibited by cortisol, and glucose disposal capacity is expected to be reduced. Indeed, the blood glucose pattern in conscious group seems to be grossly normal, but our estimation of KG between 15 and 30 minutes after glucose bolus can differentiate marginal but significant decrease in the glucose disappearance rate compared with propofol group. The time to return to basal level in conscious group also tended to be longer than in propofol group. Moreover, insulin and C-peptide concentration in conscious group where serum cortisol levels remained higher during IVGTT showed significant decreases compared with those in propofol group (Fig. 3). Collectively, our results suggest that propofol not only relieved physical stress during IVGTT procedure, but also increased insulin secretion and enhanced glucose tolerance in monkeys. In support of this notion, chronic glucocorticoid therapy and the syndrome of cortisol excess are associated with increased glucose concentration, glucose intolerance, and diabetes by several mechanisms including suppression of insulin secretion from pancreatic b-cells [14]. To date, there are some studies that have examined the effects of different anesthetic agents on glucose tolerance variables during IVGTT. Kamine et al. [8] have examined the effects of tiletamine and zolazepam and/or medetomidine on glucose tolerance in captive Japanese black bears and found that medetomidine but not zolazepam caused hyperglycemia. Several reports also showed that ketamine and diazepam caused hyperglycemia in rabbits and baboons [6, 10]. By contrast, Ionut J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
et al. [7] reported that a prior administration of acepromazine during IVGTT did not interfere with glucose metabolism in dogs. Kitamura et al. [9] showed that sevoflurane caused severe hyperglycemia during sigmoid colostomy, but propofol did not affect blood glucose levels in rats. Collectively, these results suggested that if suitable doses and/or classes of anesthetic agents were used, the anesthesia-induced blood glucose disturbance can be minimized with keeping normal physiological responses. Unfortunately, this study by using propofol did not achieve this primary goal, but instead found IVGTT in conscious state can induce systemic stress reflected by increase of serum cortisol, thereby leading to mild glucose intolerance. There are several limitations in the present study. First, the number of animals is too small (n = 4) to obtain more convincing data with strong statistical power, although some data such as KG and C-peptide reached statistical significance. If more animals will be used in the future study, clearer conclusion will be made. Second, only single anesthetic agent was used. Although the concern about the increased risk of seizure by using phenothiazine in humans made us to choose propofol as a primary agent [2], the applicability of other anesthetic agents such as acepromazine needs further study. In summary, the results of this study demonstrated that propofol not only relieved physical stress, but enhanced glucose tolerance by increasing insulin and C-peptide secretion in monkeys. Acknowledgments This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health &Welfare, Republic of Korea (grant number: HI13C0954). 245
Effect of propofol on IVGTT in rhesus monkey
Kim et al.
References 1 Bingley PJ, Colman P, Eisenbarth GS, Jackson RA, McCulloch DK, Riley WJ, Gale EA: Standardization of IVGTT to predict IDDM. Diabetes Care 1992; 15:1313–6. 2 Drynan EA, Gray P, Raisis AL: Incidence of seizures associated with the use of acepromazine in dogs undergoing myelography. J Vet Emerg Crit Care (San Antonio) 2012; 22:262–6. 3 Dufrane D, Maillart JF, Aouassar N, Goebbels RM, Guiot Y, Gianello P: Native pancreatic alpha-cell adaptation in streptozotocin-induced diabetic primates: importance for pig islet xenotransplantation. Xenotransplantation 2009; 16:152–63. 4 Fanton JW, Zarr SR, Ewert DL, Woods RW, Koenig SC: Cardiovascular responses to propofol and etomidate in long-term instrumented rhesus monkeys (Macaca mulatta). Comp Med 2000; 50: 303–8. 5 Furuya H, Kimura T, Murakami M, Katayama K, Hirose K, Yamaguchi A: Revascularization and function of pancreatic islet isografts in diabetic rats following transplan-
246
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7
8
9
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tation. Cell Transplant 2003; 12:537–44. Illera JC, Gonzalez Gil A, Silvan G, Illera M: The effects of different anaesthetic treatments on the adreno-cortical functions and glucose levels in NZW rabbits. J Physiol Biochem 2000; 56:329–36. Ionut V, Kirkman EL, Bergman RN: Investigation of the effect of acepromazine on intravenous glucose tolerance tests in dogs. Am J Vet Res 2004; 65:1124–7. Kamine A, Shimozuru M, Shibata H, Tsubota T: Effects of intramuscular administration of tiletamine-zolazepam with and without sedative pretreatment on plasma and serum biochemical values and glucose tolerance test results in Japanese black bears (Ursus thibetanus japonicus). Am J Vet Res 2012; 73:1282–9. Kitamura T, Ogawa M, Kawamura G, Sato K, Yamada Y: The effects of sevoflurane and propofol on glucose metabolism under aerobic conditions in fed rats. Anesth Analg 2009; 109:1479–85. Lehmann R, Wagner JL, Fernandez LA, Bourgoignie JJ, Ricordi C,
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J Med Primatol 43 (2014) 242–246 © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
