NeuroToxicology 48 (2015) 1–8

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NeuroToxicology

Altered transition metal homeostasis in the cuprizone model of demyelination Nataliya Moldovan, Alia Al-Ebraheem, Lianne Lobo, Raina Park, Michael J. Farquharson, Nicholas A. Bock * Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada

A R T I C L E I N F O

A B S T R A C T

Article history: Received 14 October 2014 Accepted 25 February 2015 Available online 6 March 2015

In the cuprizone model of demyelination, the neurotoxin cuprizone is fed to mice to induce a reproducible pattern of demyelination in the brain. Cuprizone is a copper chelator and it has been hypothesized that it induces a copper deficiency in the brain, which leads to demyelination. To test this hypothesis and investigate the possible role of other transition metals in the model, we fed C57Bl/6 mice a standard dose of cuprizone (0.2% dry chemical to dry food weight) for 6 weeks then measured levels of copper, manganese, iron, and zinc in regions of the brain and visceral organs. As expected, this treatment induced demyelination in the mice. We found, however, that while the treatment significantly reduced copper concentrations in the blood and liver in treated animals, there was no significant difference in concentrations in brain regions relative to control. Interestingly, cuprizone disrupted concentrations of the other transition metals in the visceral organs, with the most notable changes being decreased manganese and increased iron in the liver. In the brain, manganese concentrations were also significantly reduced in the cerebellum and striatum. These data suggest a possible role of manganese deficiency in the brain in the cuprizone model. ß 2015 Elsevier Inc. All rights reserved.

Keywords: Cuprizone model Demyelination C57Bl/6 mice Transition metals X-ray fluorescence (XRF) Neutron activation analysis (NAA)

1. Introduction The chemical cuprizone is administered to rodents to produce a model of demyelination that is widely used to study the mechanisms of myelin loss in the brain in disorders such as Multiple Sclerosis (MS) (Gudi et al., 2014). Cuprizone is a known copper chelator in vitro (Peterson, 1955) and causes axonal demyelination when administered to rodents through their diet; hence, it has been hypothesized that its mechanism of toxicity is an induced copper deficiency in brain tissue. Cuprizone is commonly administered to C57BL/6 mice, as this strain seems particularly susceptible to the resulting demyelination (Skripuletz et al., 2008). Following a weeks-long exposure to cuprizone, astrogliosis and oligodendrocyte apoptosis are observed in the brain, with demyelination evident after 4–6 weeks in multiple structures (Falangola et al., 2014). This loss of myelin is most widely reported in the corpus callosum (Falangola

* Corresponding author at: General Sciences Building, Room 105, Department of Medical Physics, McMaster University, Ontario, Canada, L8S 4L8, Tel.: +1 905 525 9140x21437; fax: +1 905 522 5982. E-mail address: [email protected] (N.A. Bock). http://dx.doi.org/10.1016/j.neuro.2015.02.009 0161-813X/ß 2015 Elsevier Inc. All rights reserved.

et al., 2014; Steelman et al., 2012) but occurs in other myelinated brain areas including the striatum (Pott et al., 2009), cerebellum (Groebe et al., 2009; Skripuletz et al., 2010), hippocampus (Koutsoudaki et al., 2009) and cortex (Gudi et al., 2009; Skripuletz et al., 2008). Outside of the brain, mice treated with cuprizone also demonstrate liver dysfunction (Suzuki and Kikkawa, 1969). A standard treatment protocol of feeding 8-week-old C57BL/6 mice 0.2% cuprizone for 6 weeks has been shown to produce acute demyelination while minimizing hepatic toxicity and the mortality rate of the mice (Torkildsen et al., 2008). There have in fact been few studies into cuprizone’s effect on copper concentrations in brain tissue, and the literature does not provide conclusive evidence that cuprizone causes copper deficiency in the brain. An early study indeed found decreased copper levels in whole brains of Swiss mice fed a 0.5% cuprizone diet for 3–4 weeks (Venturini, 1973). Recent studies, however, have actually reported increased levels of copper in several brain regions following chronic cuprizone treatment in CD mice for 3, 6, and 9 months with 0.2% cuprizone administrated in drinking water (Zatta et al., 2005) and in C57BL/6 mice fed 0.2% cuprizone for 1 week (Tezuka et al., 2013). The discrepancies in the findings could be the result of differences in mouse strains, cuprizone administration, and the time course of administration, or a true

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misinterpretation of cuprizone’s ability to reduce copper levels in the brain. To further determine whether cuprizone’s method of action is to reduce copper concentrations in brain tissue, we investigate in this paper copper concentrations in the blood, liver, kidneys, and brain regions of C57BL/6 male mice fed 0.2% cuprizone for 6 weeks compared to controls, as this has become a standard treatment regime for demyelination studies. We also investigate levels of manganese, iron, and zinc, since the homeostasis of these transition metals are linked (Garcia et al., 2006; Gunshin et al., 1997; Scheuhammer and Cherian, 1981) and it may be that changes in copper levels in the body may disrupt the levels of these other transition metals. 2. Materials and methods 2.1. Animal model All experiments were approved by the Animal Research Ethics Board at McMaster University and were carried out in male C57Bl/ 6 mice (Jackson Laboratories, ME). Control (n = 15) and treated (n = 15) groups of mice were ordered at 7 weeks old and allowed to acclimatize for 1 week prior to onset of the experiment, such that the cuprizone treatments began when the animals were 8 weeks old. All animals were housed five to a cage, provided with food and tap water ad libitum and kept on a 12 h light/dark cycle. Cuprizone (Sigma–Aldrich, MO) was milled into 8640 Teklad 22/5 rodent chow (Harlan Laboratories Inc., WI) at a concentration of 0.2% dry chemical to dry food weight and formed into half-inch pellets. A treated group of mice was fed this 0.2% cuprizone diet for 6 weeks. A control group of mice were fed standard 8640 Teklad 22/5 Rodent Diet (Harlan Laboratories, Inc., WI). Treated animals were observed once daily and all animals were weighed weekly during treatment and sacrificed at end of the 6 week time-course. For euthanasia, each mouse was induced with 5% isofluorane in 100% oxygen to reach surgical level anesthesia. The thorax was cut open and blood was drawn from the left ventricle by cardiac puncture. Kidney and liver tissue samples were obtained by dissection. The animal was then decapitated and the brain was harvested intact. The whole brain was snap-frozen in isopentane cooled in a liquid nitrogen bath to prevent diffusion of metal ions throughout the tissue prior to dissection. Control and treated brains were partially thawed and the following regions were dissected: the cortex (sampled in the frontal region), the cerebellum (entire), thalamus (sampled in a medial region), the striatum (entire), and the hippocampus (entire). The wet weight of all samples was recorded. We were not able collect enough corpus callosum tissue for metal measurements, especially in the cuprizone-treated mice. 2.2. Histopathology Pathology was investigated in three control and three treated animals. For whole-body perfusion, each animal was induced with 65 mg/kg body weight of sodium pentobarbital to reach surgical level anesthesia. The thorax was cut open and deflected and a 0.1 ml heparin sodium solution was injected into the left ventricle. A needle attached to a bag of lactated Ringers solution located 50 cm above the mouse was placed in the left ventricle. The right atrium was cut and the Ringers solution was allowed to flow through the animal, washing out the blood. After 5 min of flow, the solution was replaced with 10% phosphate-buffered formalin and allowed to flow for 6 more min. The brain was dissected and further fixed in formalin overnight. Coronal blocks of the brain were cut and dehydrated by a series of rising concentrations of alcohols from 50–100% and then xylene. The tissues were embedded in paraffin and 5 mm thick sections were cut, mounted

on glass slides and costained with hematoxylin and eosin (H&E) and luxol fast Blue (LFB), a myelin stain. The slides with tissues were coverslipped and analyzed under a Nikon Eclipse 50i light microscope by a pathologist blinded to the treatment of individual mice. Representative areas of the corpus callosum, striatum, and cerebellum were photographed. 2.3. X-ray fluorescence (XRF) measurements XRF was used to measure iron, copper, and zinc content in the tissue samples (Al-Ebraheem et al., 2009). Fresh tissue was mounted into XRF sample holders with the sample forming a disc 2 mm thick and 4 mm in diameter. The samples were kept frozen at –80 8C and allowed to thaw for a few minutes prior to the measurement. The Xray source was a Molybdenum target tube. The output beam was monochromated to approximately 17.5 keV and focused on a sample size of 2 by 2 mm using a multi-layer X-ray optics device. Samples were mounted at 908 between the incident X-ray beam and the XRF detector and located 0.5 cm away from the XRF detector during data collection. Measurements were made with the X-ray tube operating at 50 kV and 500 mA with a counting time of 2,6100 s, or at 50 kV and 320 mA with a counting time of 52,200 s. The elements of interest (iron, copper, and zinc) were identified by the photopeaks associated with their K-alpha fluorescence photon emission at 6.4 keV and 8.04 keV, respectively. To quantify the concentration of iron and copper in the tissue samples, calibration curves were constructed for each element. Calibration solutions with known concentrations of the elements (0–65 ppm iron, 0–50 ppm copper, 0–50 ppm zinc) were measured using the same procedure as the tissue samples. A linear relationship between the elemental quantity and ratio of fluorescence to scatter photopeak areas over the relevant concentration range was established. The linear calibration equations were used to quantify the iron, copper, and zinc concentrations in the tissue samples. XRF spectra were analyzed using PeakFit spectrometry analysis software (PeakFitTM SPSS, Inc., AISN Software, Inc.). The fluorescence photopeaks were smoothed and the background was subtracted. A Gaussian function was used to fit the photopeaks and the net area of the peak was determined. The same procedure was applied to analyze the escape silicon peak, tail, Compton, and Coherent scatter peaks of every spectrum. The total scatter peak area was used as a normalization factor for the detected fluorescence photons. The ratio of fluorescence to scatter peak areas was then used to calculate the elemental concentrations in the samples. The accuracy of the XRF method for quantification of copper, iron and zinc in tissue samples was validated using a standard reference material of the same weight as the samples (Table 1). This material was homogenized lobster (LUTS-1, ‘‘Non defatted lobster hepatopancreas reference material for trace elements,’’ National Research Council, Canada) due to its material matrix of mainly water and lipid, similar to brain tissue. 2.3.1. Neutron activation analysis (NAA) NAA was used to measure the manganese content in the tissue specimens. Samples were mounted in polyethylene tubes and

Table 1 Certified and experimental concentrations of Cu, Fe and Zn in the LUTS-1, ‘‘Nondefatted lobster hepatopancreas reference material for trace elements,’’ National Research Council, Canada. Element

Certified value (mg/kg)

Experimental value (mg/kg)

Cu Fe Zn

15.9  1.2 11.6  0.9 12.4  0.8

17.4  1.4 12.4  2.5 16.5  3.4

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Table 2 Certified and experimental concentrations of Mn in the bovine muscle powder (beef) standard (Reference Material 8414) [National Institute of Standards and Technology, USA]. Element

Certified value (mg/g)

Experimental value (mg/g)

Mn

0.37  0.09

0.39  0.09

freeze dried prior to measurement. Comparative NAA measurements were performed in order to quantify the concentration of manganese in the samples. Standards of 1 mg manganese were made up from a 1000 mg/mL standard manganese stock solution (J.T. Baker 6458-04, NJ). The standards and specimens were irradiated for 1200 s using a thermalized neutron irradiation site at the McMaster Nuclear Reactor. After a 4500 s delay time, the irradiated samples were measured using an Aptec HPGe spectroscopy system with a counting time of 600 s. The standards were measured as the first and last samples and averaged to account for temporal differences in neutron flux. The photopeak associated with the 847 keV gamma ray decay of 56 Mn was chosen for analysis since it has the highest emission probability. The area of the peak was determined using the Aptec software for the standards and tissue samples. The ratio of the specimen to averaged standard peak areas was used to calculate the mass of manganese in the specimen. The manganese concentration in a given tissue sample was then obtained by dividing the mass of manganese in the sample by the wet weight of the sample. The accuracy of the comparative NAA method for quantification of manganese in tissue was validated using United States’ National Institute of Standards and Technology (NIST) certified bovine muscle powder (beef) standard (Reference Material 8414) containing a similar weight of Mn to the freeze-dried tissue samples (Table 2).

Fig. 1. Weights of control and cuprizone-treated mice (m  s, n = 15 for each group). The cuprizone treatment began on the first day the mice reached 8 weeks of age and continued daily for 6 weeks until the mice reached 14 weeks of age.

2.4. Statistical analysis Statistical analyses were performed using SPSS software (IBM SPSS Statistics Version 20.0, IBM Corp.). Data was first assessed for normality using the Shapiro–Wilk test of normality. Levene’s test of equality of error variances was then used to test the homogeneity of variances of the metal concentrations across groups. A two-way ANOVA followed by a Tukey HSD post-hoc test were used to test the significant differences in weights of the control and cuprizone treated mice throughout the 6-week treatment. Significant differences in metal concentration between the brain regions of control and cuprizone treated mice were tested using a two-way ANOVA and Tukey HSD post-hoc test. The significant differences in manganese, copper, iron, and zinc

Fig. 2. Histopatholgy to assess demyelination. Panel A Crops from low magnification (2) and high magnification (40) photographs made at a location showing the corpus callosum and striatum in control and cuprizone-treated animals. The asterix denotes uneven staining in the corpus callosum of the treated animal. The arrow denotes fewer striasomes in the lateral aspect of the striatum in the treated animals. Panel B Crops from low magnification (2x) and high magnification (40) photographs made in the region of the cerebellum. (Key: CC, corpus callosum; Cor, cerebral cortex; Str, striatum; DCW, deep cerebellar gray matter).

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concentrations in the blood, liver, and kidney data were tested using an independent T-test or the Mann–Whitney U-test, depending on the normality of the data.

3. Results 3.1. General animal health During cuprizone treatment, the mice were weighed and monitored for adverse health effects such as weight loss, listlessness, anorexia, ataxia, and tremors previously described during administration of cuprizone at higher doses (Stidworthy et al., 2003). The weights of the control and cuprizone-treated mice over the course of the experiment are shown in Fig. 1. There were no significant differences between the weights of the two groups (p < 0.05), although from three weeks until sacrifice, the weights of the cuprizone-treated mice were slightly lower by 3–6% compared to controls. During the experiment the cuprizone-treated mice did not present with any major abnormal clinical symptoms, save for mild lethargy.

3.2. Histopathology Fig. 2 shows representative histopathological features we observed in the cuprizone-treated mice indicating the expected demyelination in corpus callosum in the model (Torkildsen et al., 2008). Specifically, the treated animals had uneven luxol fast Blue (LFB) staining in the corpus callosum relative to control animals, revealing an expected loss of myelin in the structure. There were also suggestions of previously reported myelin loss in other structures, including fewer stained striasomes in the more lateral aspects of the striatum in the treated animals (Pott et al., 2009), and uneven staining in the deep cerebellar white matter (Skripuletz et al., 2010). 3.3. Copper measurements Fig. 3 shows copper concentrations in the blood, kidney, and liver of control and cuprizone-treated animals. In the blood, copper decreased by 0.47 mg/mg copper weight/wet tissue weight in the treated mice (significant at the p < 0.05 level) – a 52% reduction from control. Copper concentration was not significantly different

Fig. 3. Copper concentration (metal weight/wet tissue weight, m  s, n = 5 for each group) in the blood, visceral organs and brain regions of control and cuprizone-treated mice. Statistical significance at p < 0.05 between control and treated groups is denoted by the * symbol.

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(p < 0.05 level) in the kidney in the treated and control animals, but decreased significantly (at p < 0.05) by 1.38 mg/mg in the liver of treated animals – a reduction of 21%. In the brain regions of cuprizone treated mice, however, we did not find any significant changes in copper concentrations. 3.4. Manganese measurements Fig. 4 shows manganese concentrations in the blood, kidney, and liver of control and cuprizone-treated animals. While there was no significant change in manganese concentration in the blood of the cuprizone-treated animals, manganese concentrations were significantly decreased (at p < 0.05 level) in the kidney and liver of treated mice, with decreases of 0.33 mg/mg manganese weight/ wet tissue weight and 0.57 mg/mg respectively. These corresponded to a percentage decrease in manganese concentration of 21% in the kidney and 35% in the liver. In the brain regions of cuprizone-treated mice, we also found significant decreases (at p < 0.05 level) in manganese concentrations in the cerebellum and striatum relative to control. Concentrations in the cerebellum were reduced by 0.49 mg/mg (41%) and in the striatum, by 0.35 mg/mg (30%).

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3.5. Iron measurements Fig. 5 shows iron concentrations in the blood, kidney, and liver of control and cuprizone-treated animals. While there was no significant change in iron concentration in the blood or kidney of the cuprizone-treated animals, the iron concentration was significantly increased (at p < 0.05 level) in the liver of treated mice by 31 mg/mg. This represented a percentage increase in iron concentration of 39%. In the brain regions of cuprizone treated mice, however, we did not measure any significant changes in iron concentrations. 3.6. Zinc measurements Fig. 6 shows zinc concentrations in the blood, kidney, and liver of control and cuprizone-treated animals. While there was no significant change in zinc concentration in the blood or liver of the cuprizone-treated animals, the zinc concentration was significantly decreased (at p < 0.05 level) in the kidney of treated mice by a small amount of 1.2 mg/mg. This represented a decrease in zinc concentration of 6% and suggests that cuprizone may too disrupt systemic zinc homeostasis.

Fig. 4. Manganese concentration (metal weight/wet tissue weight, m  s, n = 5 for each group) in the blood, visceral organs and brain regions of control and cuprizone-treated mice. Statistical significance at p < 0.05 between control and treated groups is denoted by the * symbol.

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Fig. 5. Iron concentration (metal weight/wet tissue weight, m  s, n = 5 for each group) in the blood, visceral organs and brain regions of control and cuprizone-treated mice. Statistical significance at p < 0.05 between control and treated groups is denoted by the * symbol.

In the brain regions of cuprizone treated mice, however, we did not measure any significant changes in zinc concentrations. 4. Discussion The cuprizone treatment in our study was neurotoxic and produced the expected myelin loss in the corpus callosum reported by others in the C57Bl/6 strain with weeks-long treatment of 0.2% cuprizone diet (Torkildsen et al., 2008). Our measurements showed that cuprizone causes a significant copper deficiency in the blood and liver; however, we did not see evidence that this results in lower copper concentrations in brain tissues. While we were not able to measure copper concentrations in the corpus callosum, which is the major reported site of demyelination in the model, we did not see significant changes in copper in other regions such as the striatum, and cerebellum where we observed demyelination. Our inability to measure copper concentrations in the corpus callosum stemmed from the fact that we could not dissect enough tissue for XRF or NAA measurements; thus, it would be interesting to use XRF produced from a synchrotron source in future studies (Daoust et al., 2013) to better localize copper concentrations in small brain regions in prepared slices of brain tissue.

Our data suggest that in the cuprizone model, the brain maintains its copper homeostasis even in the presence of systemic copper deficiency. This does not support the hypothesis that cuprizone treatment causes demyelination in C57Bl/6 mice by reducing brain copper levels. Our findings are incidentally at odds with dietary studies in young adult (Zucconi et al., 2007) and aged mice (Bolognin et al., 2012), which report that feeding mice a copper deficient diet reduces copper concentrations systemically and in the brain. Our study was not exhaustive, however, and there are alternate explanations as to why we and other researchers have not seen lowered brain copper levels following cuprizone treatment. One explanation is that cuprizone binds to copper directly in the brain making it unavailable for metabolic processes. This could even lead to increases being seen in copper levels in brain regions if the copper/cuprizone complex has a poor clearance from brain tissue (Zatta et al., 2005). This hypothesis has been called into question, however, by a study showing that dietary cuprizone does not cross the intestinal epithelial barrier and hence, does not enter the circulation to eventually be accessible by brain tissue (Benetti et al., 2010), suggesting that copper is chelated by cuprizone directly in the gut. Another possible explanation is that there is a copper deficiency in the brain, but that it is transient. This

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Fig. 6. Zinc concentration (metal weight/wet tissue weight, m  s, n = 5 for each group) in the blood, visceral organs and brain regions of control and cuprizone-treated mice. Statistical significance at p < 0.05 between control and treated groups is denoted by the * symbol.

would require copper measurements to be made throughout the time course of cuprizone treatment. A final explanation is that it is only a small, but crucial pool of copper is reduced in brain tissue that is needed for myelin maintenance, and this is missed in bulk measurements of copper. Nonetheless, more work is needed to truly establish that a brain copper deficiency underlies demyelination in the cuprizone model. A compelling finding in our study was that cuprizone treatment alters the homeostasis of other transition metals too, mostly notably, manganese. We found a decrease in manganese in the liver on the order of the decrease we saw in copper in the liver. This data shows for the first time that cuprizone also reduces manganese concentrations systemically in C57Bl/6 mice. One explanation for this is that cuprizone chelates manganese at physiological pH, although there is no mention of this in the literature. Another explanation is that systemic disruptions in copper homeostasis cause disruptions in manganese, iron, and zinc homeostasis, since these transition metals share biological transport proteins due to their chemical and structural similarity (Fitsanakis et al., 2011). In addition to systemic decreases in manganese, we found specific significant manganese decreases in the striatum and

cerebellum of cuprizone-treated mice. Both of these structures contain substantial myelin which we showed was reduced after treatment with cuprizone. This raises the question as to whether it is actually a manganese deficiency, rather than a copper deficiency in the brain that leads to the demyelination in the cuprizone model. Researchers have previously established that the susceptibility of oligodendrocytes (Benardais et al., 2013) to the toxic effects of cuprizone lies in mitochondrial dysfunction (Acs et al., 2013). Manganese is a co-factor of several important metalloenzymes in mitochondria (Aschner et al., 2005), most notably manganese super oxide dismutase (MnSOD), and it could be that a reduction in manganese levels in brain regions causes a failure in mitochondrial metabolism which contributes to oligodendrocyte death. In fact, a previous study of proteomic analysis in C57Bl/6 mice fed 0.2% w/w cuprizone for 6 weeks showed an almost twodecrease in brain levels of MnSOD (Werner et al., 2010). Our findings suggest that the role of other transition metals, specifically manganese, in the cuprizone model should be further explored. For instance, a full study of metalloproteins in various brain regions in the model would better suggest if metal levels are being reduced to the point of disrupting the metabolism needed to maintain healthy myelination. Given the large decrease in

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manganese and increase in iron in the liver, cuprizone’s effect on metalloproteins should be also be investigated in that organ. Conflict of interest The authors declare that there are no conflicts of interest. Transparency document The Transparency document associated with this article can be found in the online version. Acknowledgements NB and MF would like to acknowledge support from the Discovery Grants program of the Natural Sciences and Engineering Research Council of Canada (NSERC), (NB RGPIN-2014-04368; MF RGPIN-2014-06065). References Acs P, Selak MA, Komoly S, Kalman B. Distribution of oligodendrocyte loss and mitochondrial toxicity in the cuprizone-induced experimental demyelination model. J Neuroimmunol 2013;262:128–31. Al-Ebraheem A, Farquharson MJ, Ryan E. The evaluation of biologically important trace metals in liver, kidney and breast tissue. Appl Radiat Isot 2009;67:470–4. Aschner M, Erikson KM, Dorman DC. Manganese dosimetry: species differences and implications for neurotoxicity. Crit Rev Toxicol 2005;35:1–32. Benardais K, Kotsiari A, Skuljec J, Koutsoudaki PN, Gudi V, Singh V, Vulinovic F, Skripuletz T, Stangel M. Cuprizone [bis(cyclohexylidenehydrazide)] is selectively toxic for mature oligodendrocytes. Neurotox Res 2013;24:244–50. Benetti F, Ventura M, Salmini B, Ceola S, Carbonera D, Mammi S, Zitolo A, D’Angelo P, Urso E, Maffia M, Salvato B, Spisni E. Cuprizone neurotoxicity, copper deficiency and neurodegeneration. Neurotoxicology 2010;31:509–17. Bolognin S, Pasqualetto F, Mucignat-Caretta C, Scancar J, Milacic R, Zambenedetti P, Cozzi B, Zatta P. Effects of a copper-deficient diet on the biochemistry, neural morphology and behavior of aged mice. PLoS ONE 2012;7:e47063. Daoust A, Barbier EL, Bohic S. Manganese enhanced MRI in rat hippocampus: a correlative study with synchrotron X-ray microprobe. Neuroimage 2013;64:10–8. Falangola MF, Guilfoyle DN, Tabesh A, Hui ES, Nie X, Jensen JH, Gerum SV, Hu C, LaFrancois J, Collins HR, Helpern JA. Histological correlation of diffusional kurtosis and white matter modeling metrics in cuprizone-induced corpus callosum demyelination. NMR Biomed 2014;27:948–57. Fitsanakis VA, Zhang N, Avison MJ, Erikson KM, Gore JC, Aschner M. Changes in dietary iron exacerbate regional brain manganese accumulation as determined by magnetic resonance imaging. Toxicol Sci 2011;120:146–53. Garcia SJ, Gellein K, Syversen T, Aschner M. A manganese-enhanced diet alters brain metals and transporters in the developing rat. Toxicol Sci 2006;92:516–25.

Groebe A, Clarner T, Baumgartner W, Dang J, Beyer C, Kipp M. Cuprizone treatment induces distinct demyelination, astrocytosis, and microglia cell invasion or proliferation in the mouse cerebellum. Cerebellum 2009;8:163–74. Gudi V, Moharregh-Khiabani D, Skripuletz T, Koutsoudaki PN, Kotsiari A, Skuljec J, Trebst C, Stangel M. Regional differences between grey and white matter in cuprizone induced demyelination. Brain Res 2009;1283:127–38. Gudi V, Gingele S, Skripuletz T, Stangel M. Glial response during cuprizone-induced de- and remyelination in the CNS: lessons learned. Front Cell Neurosci 2014;8:73. Gunshin H, Mackenzie B, Berger UV, Gunshin Y, Romero MF, Boron WF, Nussberger S, Gollan JL, Hediger MA. Cloning and characterization of a mammalian protoncoupled metal-ion transporter. Nature 1997;388:482–8. Koutsoudaki PN, Skripuletz T, Gudi V, Moharregh-Khiabani D, Hildebrandt H, Trebst C, Stangel M. Demyelination of the hippocampus is prominent in the cuprizone model. Neurosci Lett 2009;451:83–8. Peterson REB, Bollier ME. Spectrophotometric determination of serum copper with biscyclohexanoneoxalyldihydrazone. Anal Chem 1955;27:1195–7. Pott F, Gingele S, Clarner T, Dang J, Baumgartner W, Beyer C, Kipp M. Cuprizone effect on myelination, astrogliosis and microglia attraction in the mouse basal ganglia. Brain Res 2009;1305:137–49. Scheuhammer AM, Cherian MG. The influence of manganese on the distribution of essential trace elements. I. Regional distribution of Mn, Na, K, Mg, Zn, Fe, and Cu in rat brain after chronic Mn exposure. Toxicol Appl Pharmacol 1981;61:227–33. Skripuletz T, Lindner M, Kotsiari A, Garde N, Fokuhl J, Linsmeier F, Trebst C, Stangel M. Cortical demyelination is prominent in the murine cuprizone model and is straindependent. Am J Pathol 2008;172:1053–61. Skripuletz T, Bussmann JH, Gudi V, Koutsoudaki PN, Pul R, Moharregh-Khiabani D, Lindner M, Stangel M. Cerebellar cortical demyelination in the murine cuprizone model. Brain Pathol 2010;20:301–12. Steelman AJ, Thompson JP, Li J. Demyelination and remyelination in anatomically distinct regions of the corpus callosum following cuprizone intoxication. Neurosci Res 2012;72:32–42. Stidworthy MF, Genoud S, Suter U, Mantei N, Franklin RJ. Quantifying the early stages of remyelination following cuprizone-induced demyelination. Brain Pathol 2003;13:329–39. Suzuki K, Kikkawa Y. Status spongiosus of CNS and hepatic changes induced by cuprizone (biscyclohexanone oxalyldihydrazone). Am J Pathol 1969;54:307–25. Tezuka T, Tamura M, Kondo MA, Sakaue M, Okada K, Takemoto K, Fukunari A, Miwa K, Ohzeki H, Kano S, Yasumatsu H, Sawa A, Kajii Y. Cuprizone short-term exposure: astrocytic IL-6 activation and behavioral changes relevant to psychosis. Neurobiol Dis 2013;59:63–8. Torkildsen O, Brunborg LA, Myhr KM, Bo L. The cuprizone model for demyelination. Acta Neurol Scand Suppl 2008;188:72–6. Venturini G. Enzymatic activities and sodium, potassium, and copper concentrations in mouse brain and liver after cuprizone treatment in vivo. J Neurochem 1973;21:1147–51. Werner SR, Saha JK, Broderick CL, Zhen EY, Higgs RE, Duffin KL, Smith RC. Proteomic analysis of demyelinated and remyelinating brain tissue following dietary cuprizone administration. J Mol Neurosci 2010;42:210–25. Zatta P, Raso M, Zambenedetti P, Wittkowski W, Messori L, Piccioli F, Mauri PL, Beltramini M. Copper and zinc dismetabolism in the mouse brain upon chronic cuprizone treatment. Cell Mol Life Sci 2005;62:1502–13. Zucconi GG, Cipriani S, Scattoni R, Balgkouranidou I, Hawkins DP, Ragnarsdottir KV. Copper deficiency elicits glial and neuronal response typical of neurodegenerative disorders. Neuropathol Appl Neurobiol 2007;33:212–25.

Altered transition metal homeostasis in the cuprizone model of demyelination.

In the cuprizone model of demyelination, the neurotoxin cuprizone is fed to mice to induce a reproducible pattern of demyelination in the brain. Cupri...
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