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1,2-Dichloropropane (1,2-DCP) is recognized as the causative agent for cholangiocarcinoma among offset color proof-printing workers in Japan. The aim of the present study was to characterize the molecular mechanisms of 1,2-DCP-induced hepatotoxic effects by proteomic analysis. We analyzed quantitatively the differential expression of proteins in the mouse liver and investigated the role of P450 in mediating the effects of 1,2-DCP. Male C57BL/6JJcl mice were exposed to 0, 50, 250, or 1250 ppm 1,2-DCP and treated with either 1-aminobenzotriazole (1-ABT), a nonselective P450 inhibitor, or saline, for 8 h/day for 4 weeks. Two-dimensional difference in gel electrophoresis (2D-DIGE) combined with matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF/MS) was used to detect and identify proteins affected by the treatment. PANTHER overrepresentation test on the identified proteins was conducted. 2D-DIGE detected 61 spots with significantly different intensity between 0 and 250 ppm 1,2-DCP groups. Among them, 25 spots were identified by MALDI-TOF/TOF/MS. Linear regression analysis showed significant trend with 1,2-DCP level in 17 proteins in mice co-treated with 1-ABT. 1-ABT mitigated the differential expression of these proteins. The gene ontology enrichment analysis showed overrepresentation of proteins functionally related to nickel cation binding, carboxylic ester hydrolase activity, and catalytic activity. The results demonstrated that exposure to 1,2-DCP altered the expression of proteins related with catalytic and carboxylic ester hydrolase activities, and that such effect was mediated by P450 enzymatic activity.

Acrylamide, a soft electrophile, is widely used in the industry and laboratories, and also contaminates certain foods. Neurotoxicity and neurodegenerative effects of acrylamide have been reported in humans and experimental animals, although the underlying mechanism remains obscure. Activation of microglia and neuroinflammation has been demonstrated in various neurodegenerative diseases as well as other pathologies of the brain. The present study aimed to investigate the role of microglial activation and neuroinflammation in acrylamide neurotoxicity. Male 10-week-old Wistar rats were exposed to acrylamide by gavage at 0, 0.2, 2, or 20 mg/kg BW, once per day for 5 weeks. The results showed that 5-week exposure to acrylamide induced inflammatory responses in the cerebral cortex, evident by upregulated mRNA and protein expression of pro-inflammatory cytokines IL-1β, IL-6, and IL-18. Acrylamide also induced activation of microglia, indicated by increased expression of microglial markers, CD11b and CD40, and increased CD11b/c-positive microglial area and microglial process length. In vitro studies using BV-2 microglial cells confirmed microglial inflammatory response, as evident by time- (0-36 h; 50 μM) and dose- (0-500 μM; 24 h) dependent increase in mRNA expression of IL-1β and IL-18, as well as the inflammatory marker iNOS. Furthermore, acrylamide-induced upregulation of pro-inflammatory cytokines was mediated through the NLRP3 inflammasome pathway, as evident by increased expression of NLRP3, caspase 1, and ASC in the rat cerebral cortex, and by the inhibitory effects of NLRP3 inflammasome inhibitor on the acrylamide-induced upregulation of NLRP3, caspase 1, IL-1β, and IL-18 in BV-2 microglia.

Acrylamide has been used industrially and also found in certain foods cooked at high temperatures. Previous reports described acrylamide-related human intoxication who presented with ataxia, memory impairment, and/or illusion. The aim of this study was to characterize the molecular mechanisms of neurotoxicity of acrylamide by analyzing the expression levels of various proteins in the hippocampus of rats exposed to acrylamide. Male Wistar rats were administered acrylamide by gavage at 0, 2, and 20 mg/kg for 1 week or 0, 0.2, 2, and 20 mg/kg for 5 weeks. At the end of the experiment, the hippocampus was dissected out and proteins were extracted for two-dimensional difference gel electrophoresis combined with matrix-assisted laser-desorption ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF/MS). MALDI-TOF/TOF/MS identified significant changes in two proteins in the 1-week and 22 proteins in the 5-week exposure groups. These changes were up-regulation in 9 and down-regulation in 13 proteins in the hippocampus of rats exposed to acrylamide at 20 mg/kg for 5 weeks. PANTHER overrepresentation test based on the GO of biological process showed significant overrepresentation in proteins annotated to nicotinamide nucleotide metabolic process, coenzyme biosynthetic process, pyruvate metabolic process, and carbohydrate metabolic process. The test also showed significant overrepresentation in proteins annotated to creatinine kinase activity for the GO of molecular function as well as myelin sheath, cytoplasmic part, and cell body for the GO of cellular component. Comparison with a previous proteomic study on hippocampal proteins in rats exposed to 1-bromopropane identified triosephosphate isomerase, mitochondrial creatine kinase U-type, creatine kinase β-type and proteasome subunit α type-1 as proteins affected by exposure to acrylamide and 1-bromopropane, suggesting a common mechanism of neurotoxicity for soft electrophiles.