Hydrogen sulfide (H 2 S) as the third gasotransmitter molecule serves various biological regulatory roles in health and disease. Acrylonitrile (AN) is a common occupational toxicant and environmental pollutant, causing brain and liver damage in mammals. The biotransformation of AN is dependent-upon reduced glutathione (GSH), cysteine and other sulfur-containing compounds. However, the effects of AN on the endogenous H 2 S biosynthesis pathway have yet to be determined. Herein, we demonstrated that a single exposure to AN (at 25, 50, or 75 mg/kg for 1, 6 or 24 h) decreased the endogenous H 2 S content and H 2 S-producing capacity in a dose-dependent manner, both in the cerebral cortex and liver of rats in vivo . In addition, the inhibitory effects of AN (1, 2.5, 5, 10 mM for 12 h) on the H 2 S content and/or the expression of H 2 S-producing enzymes were also found both in primary rat astrocytes and rat liver cell line (BRL cells). Impairment in the H 2 S biosynthesis pathway was also assessed in primary rat astrocytes treated with AN. It was found that inhibition of the cystathionine-β-synthase (CBS)/3-mercaptopyruvate sulfurtransferase (3-MPST)-H 2 S pathway with the CBS inhibitor or 3-MPST-targeted siRNA significantly increased the AN-induced (5 mM for 12 h) cytotoxicity in astrocytes. In turn, CBS activation or 3-MPST overexpression as well as exogenous NaHS supplementation significantly attenuated AN-induced cytotoxicity. Taken together, endogenous H 2 S biosynthesis pathway was disrupted in rats acutely exposed to AN, which contributes to acute AN neurotoxicity in primary rat astrocytes.
Yang Bobo,Yin Changsheng,Zhang Yu,Xing Guangwei,Wang Suhua,Li Fang,Aschner Michael,Lu Rongzhu
BackgroundHydrogen sulfide (H2S), as the third gasotransmitter participates in both cellular physiological and pathological processes, including chemical-induced injuries. We recently reported acute acrylonitrile (AN) treatment inhibited endogenous H2S biosynthesis pathway in rat and astrocyte models. However, there is still no evidence to address the correlation between endogenous H2S and sub-chronic AN exposure.ObjectivesThis study aims to explore the modulatory effects of prolonged AN exposure on endogenous H2S levels and its biosynthetic enzymes in rat blood, brain and liver.MethodsA total of 50 male Sprague-Dawley rats were randomly divided into 5 groups, including the control group and AN-treated groups at dosages of 6.25, 12.5, 25 or 50 mg/kg. Rats received one exposure/day, 5 days/week, for 4 consecutive weeks. The rat bodyweight and brain/liver organ coefficient were detected, along with liver cytochrome P450 2E1(CYP2E1) expression. In addition, the H2S contents in rat serum and plasma, and in cerebral cortex and liver tissues were measured by methylene blue method. The expression of H2S-generating enzymes, including cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MPST) was also measured with Western blot both in rat cerebral cortex and liver.ResultsSubchronic exposure to AN significantly inhibited bodyweight-gain and increased the liver CYP2E1 expression compared with the control. In addition, AN significantly increased H2S levels in rat plasma and serum, but not in liver. The endogenous H2S level in rat cerebral cortex was also significantly increased upon AN treatment, when expression of the major H2S-generating enzymes, CBS and 3-MPST were significantly enhanced. However, hepatic protein levels of CBS and CSE were significantly increased, whereas hepatic levels of 3-MPST were significantly decreased.ConclusionThis study showed that sub-chronic AN exposure increased endogenous H2S contents in rat blood and brain tissues, but not liver, which may be resulted from the distinct expression profile of H2S-producing enzymes in response to AN. The blood H2S contents may be applied as a potential novel biomarker for surveillance of chronically AN-exposed populations.HighlightsSubchronic intraperitoneal exposure to acrylonitrile increased H2S content in rat blood and cerebral cortex, but not in liver.Distinct tissue expression profiles of H2S-producing enzymes contribute to the acrylonitrile-induced differential effects on the H2S level.Blood H2S level may be a biomarker for subchronic exposure to acrylonitrile.
危险品化学品经营许可证（带存储）