Effects of acrylonitrile on antioxidant status of different brain regions in rats

Neurochemistry International 55 (2009) 552–557

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Effects of acrylonitrile on antioxidant status of different brain regions in rats Lu Rongzhu a,*, Wang Suhua a, Xing Guangwei a, Ren Chunlan a, Han Fangan b, Chen Suxian a, Zhang Zhengxian a, Zhu Qiuwei a, Michael Aschner c a

Department of Preventive Medicine, School of Medicine, Jiangsu University, 301 Xuefu Rd, Zhenjiang, Jiangsu 212013, China Zhenjiang Center of Disease Control and Prevention, Zhenjiang, Jiangsu 212003, China c Department of Pediatrics, Pharmacology and Center for Molecular Neuroscience, Vanderbilt University Medical Center, Nashville, TN 37232, United States b

A R T I C L E I N F O

A B S T R A C T

Article history: Received 15 January 2009 Received in revised form 5 May 2009 Accepted 11 May 2009 Available online 20 May 2009

While the adverse effects of acrylonitrile (AN) on the central nervous system (CNS) are known to be mediated, at least in part, by the generation of free radicals and oxidative stress, there is a paucity of data on region-specific alterations in biomarkers of oxidative stress in the brain of AN-exposed animals. The present study was designed to examine the effects of AN on biomarkers of oxidative stress in several brain regions of adult Sprague–Dawley rats. Daily intraperitoneal (i.p.) treatment of animals to 0 (control, normal saline solution), 25, 50 or 75 mg AN/kg body weight for 7 days resulted in statistically significant (p < 0.05) increases in the levels of lipid peroxidation product, malondialdehyde (MDA), in the cortex and cerebellum; a statistically significant (p < 0.05) decrease MDA levels were noted in the striatum. Contents of reduced glutathione (GSH) were significantly (p < 0.05) decreased in cortex, cerebellum and hippocampus. The activities of the antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were differentially affected by AN and these effects were brain regionspecific and AN dose-dependent. Taken together, these data suggest brain region-specific effects of AN on lipid peroxidation, activities of antioxidant enzymes and non-enzymatic antioxidant levels. These effects may provide biochemical evidence for AN-induced neurobehavioral damage and disturbance of monoamine neurotransmitters. ß 2009 Elsevier Ltd. All rights reserved.

Keywords: Acrylonitrile Brain regions Antioxidant enzymes Lipid peroxidation

1. Introduction Acrylonitrile (AN), an organic nitrile, is widely used in the manufacturing of fibers, plastics and pharmaceuticals. Though human exposure to AN occurs predominantly in occupational settings (via inhalation), AN exposures may also result via the oral and dermal routes. The human nervous system response to acute AN exposure shows characteristics of cyanide poisoning (Haber and Patterson, 2005). Prolonged treatment of laboratory rodents with AN by an oral or inhalation route produces dose-dependent changes in the conduction properties of peripheral nerves that have yet to be characterized neuropathologically (Gagnaire et al., 1998). Chronic oral or inhalation treatment of rats also induces a dose-dependent increase of glial cell tumors (astrocytomas) in the brain and spinal cord accompanied by evidence of CNS oxidative stress (Jiang et al., 1998). Malignant tumors have also been reported in the ear canal, gastrointestinal tract and mammary glands, but increases in cancer incidence have not been

* Corresponding author. Tel.: +86 511 85038449; fax: +86 511 85038483. E-mail addresses: [email protected], [email protected] (L. Rongzhu). 0197-0186/$ – see front matter ß 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.neuint.2009.05.009

consistently observed in epidemiological studies (International Programme on Chemical Safety (IPCS), 2002). The exact mechanism/s of AN-induced toxicity have yet to be fully defined. Involvement of reactive oxygen species (ROS) has been posited as a likely mechanism of AN-induced toxicity (Kamendulis et al., 1999; Jiang et al., 1998). Indeed, several in vitro studies have established AN-induced oxidative stress in rat alveolar macrophages, erythrocytes and hepatocytes (Ivanov et al., 1989; Bhooma and Venkataprasad, 1997; Farooqui et al., 1990; Nerudova et al., 1988; Zitting and Heinonen, 1980). In addition, AN has been shown to selectively induce in vivo oxidative damage in brain (Jiang et al., 1998; Kamendulis et al., 1999; Mahalakshmi et al., 2003) and reactive gliosis marked by elevation of glial fibrillary acidic protein (GFAP) (Enongene et al., 2000); interestingly, from the tested neural cells, astrocytes appeared to be most sensitive to AN (Kamendulis et al., 1999). In vitro studies have also corroborated the ability of AN to induce ROS in human neuroblastoma cells, rat astrocytes and human astrocytes (Jacob and Ahmed, 2003; Cova et al., 1992; Enongene et al., 2000; Jiang et al., 1998; Kamendulis et al., 1999; Mahalakshmi et al., 2003). The brain exhibits distinct variations in cellular as well as regional distribution of antioxidant biochemical defenses (Brannan et al., 1980; Goss-Sampson et al., 1988; Ansari

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et al., 1989; Ravindranath et al., 1989; Verma and Srivastava, 2001). Thus, neural cells and/or brain regions likely differentially respond to changes in metabolic rates associated with the generation of reactive oxygen species (ROS) (Shukla et al., 1988; Hussain et al., 1995). Indeed, there is abundant evidence invoking regional sensitivity to oxidative stress that is dependent about cellular and regional redox status (Baek et al., 1999). However, data on the effects of AN on distinct CNS regions is limited to a single study by Enongene et al. (2000), where it was noted that AN led to region-specific alterations in GFAP expression levels and reduced glutathione (GSH) content. Given these limited observations, the main objective of the present study was to investigate regional changes in lipid peroxidation product, enzymatic and non-enzymatic antioxidant levels in rat exposed to AN, thus improving the mechanistic understanding of AN-induced CNS dysfunction and its relationship to redox status.

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GPx activity was estimated by the analysis of reduced GSH in the enzymatic reaction (Sedlak and Lindsay, 1968). Reduced GSH was catalyzed by GSH-Px in the presence of hydrogen peroxide. The GPx kit developed based on the above biochemical reactions from Nanjing Jiancheng Bioengineering Company, Nanjing, China was used. One unit of enzyme activity represents a decrease in GSH concentration of 1 mmol/mg wet tissue weight per minute after subtraction of nonenzymatic mode at 37 8C (Rotruck et al., 1973). Results were expressed as units of GPx activity/mg wet tissue weight and the limitation of detection was 40 units/ml reaction volume. 2.6. Statistical analysis of data All values were expressed as means  S.D. The differences between groups were analyzed by one-way analysis of variance (ANOVA) followed by the Student– Newman–Keuls (S–N–K) test for multiple post hoc comparison tests. The alpha level for the analyses was set at p < 0.05. All univariate analysis of variance (ANOVA) was completed using SPSS 10.0 software (SPSS Inc., Chicago, IL).

3. Results 3.1. Body weight and gross behavioral changes

2. Materials and methods 2.1. Chemicals AN (chemical purity >99%) was a generous gift from the Acrylonitrile Plant of Shanghai Petrochemical Company (Shanghai, China). All the chemicals were of the highest purity grade available. 2.2. Animals and treatment Thirty-two adult male Sprague–Dawley rats (250–300 g) were randomly assigned into four groups. Group I served as control and received vehicle (normal saline solution) alone. Animals in groups II, III and IV received a daily i.p. injection of AN at 25, 50 or 75 mg/kg body weight, respectively. These dosages were chosen based on our previous pilot study and a study by Working et al. (1987). AN was dissolved in normal saline solution and prepared freshly before daily injection. Treatments were carried out for 7 consecutive days. Twenty-four hours after the last injection, animals were decapitated and brains quickly excised, cleared of meninges, washed with ice-cold normal saline solution and placed on ice for regional dissection. Four regions of the brain, namely, cortex, cerebellum, hippocampus and striatum, were dissected out (Pelligrino et al., 1979). Samples were weighed followed by sonic homogenization in chilled normal saline to produce a 10% homogenate (w/v). Next, the samples were centrifuged at 719  g (2000 rpm, Megafuge 1.0R, Heraeus, Germany) for 10 min at 4 8C, and the resultant supernatants were collected and used for biochemical analyses. Determinations were performed within 24 h of sample preparation. 2.3. Lipid peroxidation product Lipid peroxidation product, the amount of malondialdehyde (MDA), formed by 2-thiobarbituric acid (TBA) reaction as thiobarbituric acid reactive substances (TBARS) were measured by the method of Utley et al. (1967), using a MDA kit (Nanjing Jiancheng Bioengineering Company, Nanjing, China). The spectrophotometric determinations were performed at 532 nm according to the manufacturer’s instructions. Results were expressed as nmol MDA/mg wet tissue weight. The limit of detection was 1.2 nmol/ml reaction volume. 2.4. Glutathione Total content of reduced glutathione (GSH) in each of the regional brain samples was determined with Ellman’s reagent, 5,50 dithiobis-(2-nitrobenzoic acid) (DTNB) (Sedlak and Lindsay, 1968). Briefly, a 10% (w/v) tissue homogenate was prepared in 5% (w/v) trichloroacetic acid and centrifuged at 719  g (2000 rpm, Megafuge 1.0R, Heraeus, Germany) for 20 min. GSH in the deproteinized supernatant was estimated with Ellman’s reagents. The spectrophotometric absorbance was determined at 420 nm using a GSH kit (Nanjing Jiancheng Bioengineering Company, Nanjing, China). Results were expressed as nmol GSH/mg wet tissue weight and the limit of detection was 4.88 nmol/ml reaction volume. 2.5. Antioxidant enzymes Analysis of SOD activity was based on SOD-mediated inhibition of nitrite formation from hydroxyammonium in the presence of O2 generators (xanthine and xanthine oxidase) (Elstner and Heupel, 1976). The amount of SOD that inhibits 50% the rate of reduction of nitrite formation in 40 min at 37 8C was regarded as one enzyme unit. A commercial SOD kit (Nanjing Jiancheng Bioengineering Company, Nanjing, China) was used for the analyses and spectrophotometric analyses was performed at 500 nm. Results were expressed as units of SOD activity/mg wet tissue and the limitation of detection was 6.25 unit/ml reaction volume.

One week after i.p. administration of AN, there were no discernible changes in body weight gain among various groups, and the AN-treated rats weights were indistinguishable from controls. One rat in the control group and two rats in the high dose (75 mg/kg) group died for unknown reasons, and these animals were excluded from further analyses. Compared with the control group, more rats in the AN treatment groups exhibited reduced motor activities in home cages during the dosing period. Excessive salivation and soiled appearances were also noted only in the ANtreated rats. Though there were some apparent dose-dependent behavioral changes, no quantitative measurements were made for assessment of neurobehavioral characterizations induced by AN, as this was deemed to be beyond the scope of the present research. 3.2. Lipid peroxidation product Statistically significant changes (F = 11.57, p < 0.05) in MDA levels were observed in the cortex of all three AN-treated groups and in the cerebellum of the high dose AN group compared to the normal saline-treated controls (F = 17.82, p < 0.05) (Fig. 1). These effects were dose-dependent and most pronounced in the high AN exposure group. Among all brain regions, the increase in lipid peroxidation products was most pronounced in the cortex. In the 75 mg/kg AN group, cortical MDA levels were more than fivefold greater than in the controls. Comparatively, the increase in cerebellar MDA levels was 35% greater in the high AN group vs. controls. Though there was a statistically significant (F = 6.41, p < 0.05) decrease in MDA levels in the striatum of the three AN groups, the largest decrease was only 18% (in the 75 mg/kg AN group compared with the control group) (Fig. 1). There was no significant changes of MDA levels in hippocampus among control and AN-treated animals (F = 2.92, p > 0.05) 3.3. Glutathione The contents of reduced GSH were statistically significantly (F = 23.39 and 8.58, p < 0.05) decreased in both the cortex and cerebellum of AN-treated rats (Fig. 2). The cortex showed AN dosedependent reduction in GSH contents. A significant decrease (p < 0.05) in GSH contents was noted in the cerebellum of the mid and the high dose AN groups compared with the control group. The pattern of change differed between the cortex and cerebellum. In the cortex, GSH contents were decreased by 10%, 19% and 24% in the 25, 50 and 75 mg AN/kg-treated groups, respectively. In contrast, in the cerebellum 50 mg AN/kg led to the highest reduction in GSH contents (23%), eclipsing the decline (14%) inherent to treatment with the highest dose (75 mg AN/kg).

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Fig. 1. Effect of subacute AN admisitration on lipid peroxidation products in cortex, cerebellum, hippocampus and striatum of rat brain. Data are expressed as mean  S.D. of 6–8 animals in each group. *vs. control; ~vs. 25 mg/kg; $vs. 50 mg/kg, p < 0.05.

Contents of cerebellar GSH in the low dose treatment group were indistinguishable from controls. While the changes in reduced GSH contents in the hippocampus showed a statistically significant dose-dependent downward trend (F = 5.33, p < 0.05), only the effect of high dose of AN was statistically decreased (20%), compared to controls. No statistically significant effect of AN treatment on GSH contents was noted in the striatum (F = 1.36, p > 0.05) (Fig. 2). 3.4. Antioxidant enzymes The effects of treatments with AN on the activity of SOD and GPx in the four brain regions are shown in Figs. 3 and 4, respectively. A decrease in the activity of SOD of AN-treated rats was noted in the cortex (F = 5.04, p < 0.05), cerebellum (F = 13.76, p < 0.01),

Fig. 2. Effect of subacute AN administration on reduced GSH contents in cortex, cerebellum, hippocampus and striatum of rat brain. Data are expressed as mean  S.D. of 6–8 animals in each group. *vs. control; ~vs. 25 mg/kg; $vs. 50 mg/kg, p < 0.05.

hippocampus (F = 50.81, p < 0.01) and striatum (F = 7.36, p < 0.01) (Fig. 3). The activity of SOD in the cortex, hippocampus and striatum at the low AN dose group was statistically significantly (p < 0.05) decreased compared with the control group. Among the changes in SOD activity, the biggest declines were noted in the hippocampus and cerebellum of the high dose AN (75 mg AN/kg) group (33 and 39%, respectively). Compared with controls, striatal SOD activity was significantly (p < 0.05) reduced in the low and mid AN treatment groups, but not in the high AN group. A parallel decrease in GPx activity was noted in cortex (F = 6.52, p < 0.01), cerebellum (F = 4.13, p < 0.05), hippocampus (F = 18.72, p < 0.01) and striatum (F = 6.55, p < 0.01), though the pattern varied from one region to another (Fig. 4). Compared with controls, the activity of GPx in the cerebellum, hippocampus and striatum even at the low dose AN group showed a statistically significant

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Fig. 3. Effect of subacute AN administration on the activity of SOD in cortex, cerebellum, hippocampus and striatum of rat brain. Data are expressed as mean  S.D. of 6–8 animals in each group. *vs. control; ~vs. 25 mg/kg; $vs. 50 mg/kg, p < 0.05.

Fig. 4. Effect of subacute AN admisitration on activity of GPx in cortex, cerebellum, hippocampus and striatum of rat brain. Data are expressed as mean  S.D. of 6–8 animals in each group. *vs. control; ~vs. 25 mg/kg; $vs. 50 mg/kg, p < 0.05.

(p < 0.05) decrease; but, the change in GPx activity in the cortex was statistically significantly (p < 0.05) decreased only at the high AN dose (75 mg/kg) body weight (Fig. 4).

cellular antioxidant contents; (2) liberation of cyanide from AN metabolism. Cyanide is a potent generator of ROS production (via inhibition of the mitochondrial respiratory chain) as well as an inhibitor of the activities of several antioxidant enzymes (Gunasekar et al., 1996; Li et al., 2002); (3) ROS generated as by-products of AN metabolism via cytochrome P450 2E1 oxidation (Wang et al., 2002). It is noteworthy that AN-induced CNS damage is attenuated by hesperidin (a flavanone glycoside—flavonoid) and taurine, two natural endogenous antioxidants (El-Sayed el-SM et al., 2008; Mahalakshmi et al., 2003), lending further support to the role of ROS in mediating AN neurotoxicity. The brain has a high rate of oxidative metabolism, consuming 20% of the cardiac output. At the same time, the brain, compared to liver, lung and other organs, contains relatively low levels of

4. Discussion Upon a single injection of [2,3-14C]acrylonitrile, AN readily passes across blood–brain barrier into the CNS, where 14C radioactivity is known to exhibit longer retention compared with other organs (Sato et al., 1982), where it is suggested to generate free radicals (Jiang et al., 1998). Three distinct pathways have been proposed: (1) AN conjugation with GSH, a metabolic process representing the major route of detoxification of AN. The process results in a rapid depletion of GSH and an overall decrease in

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enzymatic and non-enzymatic antioxidants and high amounts of peroxidizable unsaturated lipids, rendering it more vulnerable to oxidative stress compared to other tissues (Weber, 1994; Bondy, 1997). Furthermore, antioxidant systems in the CNS are not evenly distributed across brain regions (Baek et al., 1999). This heterogeneity implies differential sensitivity of CNS regions in response to environmental exposures associated with oxidative stress. Our previous work has demonstrated that AN leads to selective disturbances in monoamine neurotransmitters in the cerebellum and striatum of exposed rats, characterized by deficits in motor coordination, learning and memory (Lu et al., 2005; Rongzhu et al., 2007). Enongene et al. (2000) noted in AN-treated rats, regionspecific elevation of GFAP levels, a marker of astrocytic proliferation, generally associated with neurotoxic responses. Furthermore, in the rat, selective vacuolization of neuronal cells of the cortex and brain stem were reported upon daily i.p. injections (for 3 weeks) of 50 mg AN/kg bodyweight (Knobloch et al., 1971). These observations led us to test the hypothesis that AN-induced region-specific changes in oxidative stress in the rat brain may play a critical role in mediating AN-produced neurotoxicity. Because the cortex, cerebellum, hippocampus and striatum are involved in cognition and motor coordination, functions known to be affected by AN (Rongzhu et al., 2007), these regions were chosen as the central focus of the present study. Results from this study suggest that AN caused oxidative stress, which was dose-dependent and accompanied by concomitant decrease in the levels of reduced GSH and activities of the antioxidant enzymes, SOD and GPx. However, the brain regions appeared to be differentially affected. Among the four regions, the cortex and cerebellum displayed the highest sensitivity, showing the greatest change in lipid peroxidation and GSH depletion in response to AN treatment. In contrast, the greatest decreases in the levels of the antioxidant enzymes, SOD and GPx were inherent to the hippocampus and striatum. AN (50 mg/kg) led to no statistical significance both on SOD activity and on lipid peroxidation in the cortex and cerebellum, respectively. Notably AN (50 mg/kg) seemed to have no significant effect on lipid peroxidation in the hippocampus (Fig. 1), which may be attributable to the fact that in this brain region levels of SOD are appreciably higher compared to those in the other examined brain areas (Fig. 3). Furthermore, control levels of lipid peroxidation in the hippocampus while similar to those in the striatum, are noticeably lower vs. those in the cerebellum and cortex. These findings are in general agreement with observations by Jiang et al. (1998), El-Sayed el-SM et al. (2008) and Mahalakshmi et al. (2003). Interestingly, the pattern of regional brain lipid peroxidation, non-enzymatic antioxidant and enzymatic antioxidants was distinct from that induced by systemic exposures with hexachlorocyclohexane (Srivastava and Shivanandappa, 2005), lead (Bennet et al., 2007), cyanide (Mills et al., 1999), manganese (Taylor et al., 2006) and hypobaric hypoxia (Maiti et al., 2006). Generally, this heterogeneous pattern of responses to environmental contaminants is attributable to differential accumulation of the chemicals and/or their metabolite(s) in various brain regions, as well as differences in metabolic and detoxification enzymes in the distinct brain regions. It is generally considered that oxidative stress induced by AN should be attributable to conjunction with GSH, liberation of cyanide and leakage of free radicals during CYP2E1-mediated oxidation (Woutersen, 1998). However, the pattern of alterations of lipid peroxidation and antioxidant status we noted is inconsistent with selective damages in brain areas by cyanide and its resultant hypoxia. Mills et al. (1999) found that cyanide-induced hypoxia selectively damaged the substantia nigra (SN) and Maiti et al. (2006) described the rat hippocampus as being most sensitive

to hypobaric hypoxia compared with cortex, hippocampus and striatum. That the region-specific ROS changes induced by AN is reflective of the distribution of brain CYP2E1 is also unlikely, since high activities of cytochrome P450 2E1 are present also in the cerebellum and hippocampus (Upadhya et al., 2000; Yadav et al., 2006). In addition, AN-induced region-specific alterations of oxidative stress cannot be explained by disturbance of monoamine neurotransmitters (Lu et al., 2005), because the striatum would be expected to be the most susceptible area, where abundance of free radicals was released via autooxidation of catecholamines (Bondy, 1997). While the exact mechanisms responsible for AN’s neurotoxicity have yet to be clearly deciphered, the present study provides direct evidence that vulnerability to oxidative stress in specific brain regions likely plays a pivotal role in mediating AN-induced neurotoxicity. In summary, the findings of the present investigation suggest that various brain regions are differentially susceptible to AN-induced oxidative stress in the rat. However, alterations of lipid peroxidation products and antioxidants induced by AN are not paralleled, due to complex regulation and adaptation of balance of oxidants and antioxidants. Further studies will be needed to clarify these paradoxical findings. Acknowledgements The authors are grateful to Dr. Sam Kacew at the University of Ottawa, Dr. Jordi Llorens at the University of Barcelona, Dr. Larry Fechter at Jerry Pettis Memorial Veterans Medical Center, Loma Linda, California and Dr. Peter Spencer at Oregon Health and Science University for critical comments and suggestions on the draft manuscript. This work was in part supported by the Natural Science Foundation of China (No. 30872139) (to Lu Rongzhu), the SCI-TECH(2008-018-02) and Nutrition-Disease Team Fund of Jiangsu University, the Natural Science Foundation of Jiangsu Province (No. BK 20040061) (to Lu Rongzhu), and NIEHS ES07331 (to Michael Aschner). References Ansari, K.A., Kaplan, E., Shoeman, D., 1989. Age-related changes in lipid peroxidation and protective enzymes in the central nervous system. Growth Dev. Aging 53 (3), 117–121. Baek, B.S., Kwon, H.J., Lee, K.H., Yoo, M.A., Kim, K.W., Ikeno, Y., Yu, B.P., Chung, H.Y., 1999. Regional difference of ROS generation, lipid peroxidation, and antioxidant enzyme activity in rat brain and their dietary modulation. Arch. Pharm. Res. 22 (4), 361–366. Bennet, C., Bettaiya, R., Rajanna, S., Baker, L., Yallapragada, P.R., Brice, J.J., White, S.L., Bokara, K.K., 2007. Region specific increase in the antioxidant enzymes and lipid peroxidation products in the brain of rats exposed to lead. Free Radic. Res. 41 (3), 267–273. Bhooma, T., Venkataprasad, N., 1997. Acrylonitrile potentiate oxidative stress in rat alveolar macrophages. Bull. Environ. Contam. Toxicol. 58, 71–78. Bondy, S.C., 1997. Free-radical-mediated toxic injury to the nervous system. In: Wallace, K.B. (Ed.), Free Radical Toxicology. Taylor & Francis, Oxford, pp. 221– 248.. Brannan, T.S., Maker, H.S., Raes, I., Weiss, C., 1980. Regional distribution of glutathione reductase in the adult rat brain. Brain Res. 200 (2), 474–477. Cova, C., Fumagalli, P., Santagostino, A., 1992. Toxicity of acrylonitrile in a human neuroblastoma cell line and its effects on glutathione and glutathione-s-transferase. Bull. Environ. Contam. Toxicol. 49, 886–891. El-Sayed el-SM, Abo-Salem, O.M., Abd-Ellah, M.F., Abd-Alla, G.M., 2008. Hesperidin, an antioxidant flavonoid, prevents acrylonitrile-induced oxidative stress in rat brain. J. Biochem. Mol. Toxicol. 22 (4), 268–273. Elstner, E.F., Heupel, A., 1976. Inhibition of nitrite formation from hydroxylammoniumchloride: a simple assay for superoxide dismutase. Anal. Biochem. 70 (2), 616–620. Enongene, E.N., Sun, P.N., Mehta, C.S., 2000. Sodium thiosulfate protects against acrylonitrile-induced elevation of glial fibrillary acidic protein levels by replenishing glutathione. Environ. Toxicol. Pharmacol. 8 (2), 153–161. Farooqui, M.Y., Mumtaz, M.M., Ghanayem, B.I., Ahmed, A.E., 1990. Hemoglobin degradation, lipid peroxidation, and inhibition of Na+/K+-ATPase in rat erythrocytes exposed to acrylonitrile. J. Biochem. Toxicol. 5 (4), 221–227. Gagnaire, F., Marignac, B., Bonnet, P., 1998. Relative neurotoxicological properties of five unsaturated aliphatic nitriles in rats. J. Appl. Toxicol. 18 (1), 25–31.

L. Rongzhu et al. / Neurochemistry International 55 (2009) 552–557 Goss-Sampson, M.A., MacEvilly, C.J., Muller, D.P., 1988. Longitudinal studies of the neurobiology of vitamin E and other antioxidant systems, and neurological function in the vitamin E deficient rat. J. Neurol. Sci. 87 (1), 25–35. Gunasekar, P.G., Sun, P.W., Kanthasamy, A.G., Borowitz, J.L., Isom, G.E., 1996. Cyanide-induced neurotoxicity involves nitric oxide and reactive oxygen species generation after N-methyl-D-aspartate receptor activation. J. Pharmacol. Exp. Ther. 277 (1), 150–155. Haber, L.T., Patterson, J., 2005. Report of an independent peer review of an acrylonitrile risk assessment. Hum. Exp. Toxicol. 24 (10), 487–527. Hussain, S., Slikker Jr., W., Ali, S.F., 1995. Age-related changes in antioxidant enzymes, superoxide dismutase, catalase, glutathione peroxidase and glutathione in different regions of mouse brain. Int. J. Dev. Neurosci. 13 (8), 811–817. International Programme on Chemical Safety (IPCS), 2002. Acrylonitrile. Concise International Chemical Assessment Document 39. WHO: Geneva. Ivanov, I., Rahier, J., Lauwerys, 1989. R lipid peroxidation in acrylonitrile-treated rats, evidenced by elevated ethane production. J. Appl. Toxicol. 9 (5), 353–358. Jacob, S., Ahmed, A.E., 2003. Acrylonitrile induces oxidative stress and 8-hydroxydeoxyguanosine formation in normal human astrocytes. Toxicol. Mech. Methods 13, 169–179. Jiang, J., Xu, Y., Klaunig, J.E., 1998. Induction of oxidative stress in rat brain by acrylonitrile. Toxicol. Sci. 46, 333–341. Kamendulis, L.M., Jiang, J., Xu, Y., Klaunig, J.E., 1999. Induction of oxidative stress and oxidative damage in rat glial cells by acrylonitrile. Carcinogenesis 20 (8), 1555–1560. Knobloch, K., Szendzikowski, S., Czajkowska, T., Krysiak, B., 1971. Experimental studies on acute and subacute toxicity of acrylonitrile. Med. Pr. 22(3), 257–269 (in Polish). Cited in: IPCS, 1983. Environmental Health Criteria 28, Acrylonitrile, United Nations Environmental Programme. International Labour Organisation, World Health Organization, Geneva, Switzerland (available on-line at http:// www.inchem.org/documents/ehc/ehc/ehc28.htm). Li, L., Prabhakaran, K., Shou, Y., Borowitz, J.L., Isom, G.E., 2002. Oxidative stress and cyclooxygenase-2 induction mediate cyanide-induced apoptosis of cortical cells. Toxicol. Appl. Pharmacol. 185 (1), 55–63. Lu, R.Z., Chen, Z.Q., Jin, F.S., 2005. Effects of acrylonitrile in drinking water on monoamine neurotransmitters and its metabolites in male rat brains. Zhonghua Yu Fang Yi Xue Za Zhi (Chin. J. Prev. Med.) 39 (2), 122–125 (article in Chinese). Mahalakshmi, K., Pushpakiran, G., Anuradha, C.V., 2003. Taurine prevents acrylonitrile-induced oxidative stress in rat brain. Pol. J. Pharmacol. 55 (6), 1037–1043. Maiti, P., Singh, S.B., Sharma, A.K., Muthuraju, S., Banerjee, P.K., Ilavazhagan, G., 2006. Hypobaric hypoxia induces oxidative stress in rat brain. Neurochem. Int. 49 (8), 709–716. Mills, E.M., Gunasekar, P.G., Li, L., Borowitz, J.L., Isom, G.E., 1999. Differential susceptibility of brain areas to cyanide involves different modes of cell death. Toxicol. Appl. Pharmacol. 156 (1), 6–16. Nerudova, J., Gut, I., Savolainen, H., 1988. Consequence of acrylonitrile metaboloism in rat hepatocytes: effects on lipid peroxidation and viability of the cells. Environ. Res. 46 (2), 133–141.

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Pelligrino, L.J., Pelligrino, A.S., Cushman, A.J., 1979. A Stereotaxic Atlas of the Rat Brain. Plenum, New York. Ravindranath, V., Shivakumar, B.R., Anandatheerthavarada, H.K., 1989. Low glutathione levels in brain regions of aged rats. Neurosci. Lett. 101 (2), 187–190. Rongzhu, L., Suhua, W., Guangwei, X., Fangan, H., Ziqiang, C., Fusheng, J., Kacew, S., 2007. Neurobehavioral alterations in rats exposed to acrylonitrile in drinking water. Hum. Exp. Toxicol. 26 (3), 179–184. Rotruck, J.T., Pope, A.L., Ganther, H.E., Swanson, A.B., Hafeman, D.G., Hoekstra, W.G., 1973. Selenium: biochemical roles as a component of glutathione peroxidase. Science 179 (73), 588–590. Sato, M., Hirasawa, F., Ogata, M., Takizawa, Y., Kojima, H., Yoshida, T., 1982. Distribution and accumulation of [2,3-14C]acrylonitrile in rat after single injection. Ecotoxicol. Environ. Saf. 6 (5), 489–494. Sedlak, J., Lindsay, R.H., 1968. Estimation of total, protein-bound, and nonprotein sulfhydryl groups in tissue with Ellman’s reagent. Anal. Biochem. 25 (1), 192–205. Shukla, G.S., Srivastava, R.S., Chandra, S.V., 1988. Glutathione status and cadmium neurotoxicity: studies in discrete brain regions of growing rats. Fundam. Appl. Toxicol. 11 (2), 229–235. Srivastava, A., Shivanandappa, T., 2005. Hexachlorocyclohexane differentially alters the antioxidant status of the brain regions in rat. Toxicology 214 (1/2), 123–130. Taylor, M.D., Erikson, K.M., Dobson, A.W., Fitsanakis, V.A., Dorman, D.C., Aschner, M., 2006. Effects of inhaled manganese on biomarkers of oxidative stress in the rat brain. Neurotoxicology 27 (5), 788–797. Upadhya, S.C., Tirumalai, P.S., Boyd, M.R., Mori, T., Ravindranath, V., 2000. Cytochrome P4502E (CYP2E) in brain: constitutive expression, induction by ethanol and localization by fluorescence in situ hybridization. Arch. Biochem. Biophys. 373 (1), 23–34. Utley, H.C., Bernheim, F., Hachslein, P., 1967. Effect of sulfhydryl reagent on peroxidation in microsome. Arch. Biochem. Physiol. 114C, 29–34. Verma, R.S., Srivastava, N., 2001. Chlorpyrifos induced alterations in levels of thiobarbituric acid reactive substances and glutathione in rat brain. Indian J. Exp. Biol. 39 (2), 174–177. Wang, H., Chanas, B., Ghanayem, B.I., 2002. Cytochrome P450 2E1 (CYP2E1) is essential for acrylonitrile metabolism to cyanide: comparative studies using CYP2E1-null and wild-type mice. Drug Metab. Dispos. 30 (8), 911–917. Weber, G.F., 1994. The pathophysiology of reactive oxygen intermediates in the central nervous system. Med. Hypotheses 43 (4), 223–230. Working, P.K., Bentley, K.S., Hurtt, M.E., Mohr, K.L., 1987. Comparison of the dominant lethal effects of acrylonitrile and acrylamide in male Fischer 344 rats. Mutagenesis 2 (3), 215–220. Woutersen, R.A., 1998. Toxicologic profile of acrylonitrile. Scand. J. Work Environ. Health 24 (Suppl. 2), 5–9. Yadav, S., Dhawan, A., Singh, R.L., Seth, P.K., Parmar, D., 2006. Expression of constitutive and inducible cytochrome P450 2E1 in rat brain. Mol. Cell. Biochem. 286 (1/2), 171–180. Zitting, A., Heinonen, T., 1980. Decrease of reduced glutathione in isolated rat hepatocytes caused by acrolein, acrylonitrile, and the thermal degradation products of styrene copolymers. Toxicology 17 (3), 333–341.