title: Long term exposure to cypermethrin induces nigrostriatal dopaminergic neurodegeneration in adult rats: postnatal exposure enhances the susceptibility during adulthood.
abstract: The study aimed to investigate the effects of cypermethrin on biochemical, histopathological, and motor behavioral indices of the nigrostriatal dopaminergic system in adult rats treated with or without cypermethrin (1/10 adult dose) during postnatal days 5-19. Spontaneous locomotor activity (SLA) and rotarod tests were performed to assess motor behavior. Levels of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the striatum, and tyrosine hydroxylase (TH) immunoreactivity and 4',6-diamidino-2-phenylindole (DAPI)/Fluoro-Jade B staining in the substantia nigra were measured to assess dopaminergic neurodegeneration. Postnatal treated animals did not exhibit significant changes in any measured parameters. The significant reduction in the time of stay on rotarod, spontaneous locomotor activity, dopamine, 3,4-dihydroxyphenylacetic acid, and tyrosine hydroxylase immunoreactivity while an increase in homovanillic acid level and Fluoro-Jade B-positive cells were observed in cypermethrin treated adult rats. These changes were more pronounced in the animals treated with cypermethrin during postnatal days followed by adulthood compared with adulthood alone. The results obtained thus demonstrate that exposure to cypermethrin during adulthood induces dopaminergic neurodegeneration in rats and postnatal exposure enhances the susceptibility of animals to dopaminergic neurodegeneration if rechallenged during adulthood.
authors.affiliation: Indian Institute of Toxicology Research (Council of Scientific and Industrial Research), Lucknow, India.
authors.forename: Anand Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Manindra Nath
authors.initials: MN
authors.lastname: Tiwari
authors.forename: Ghanshyam
authors.initials: G
authors.lastname: Upadhyay
authors.forename: Devendra Kumar
authors.initials: DK
authors.lastname: Patel
authors.forename: Dhirendra
authors.initials: D
authors.lastname: Singh
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.forename: Mahendra Pratap
authors.initials: MP
authors.lastname: Singh
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000503:physiopathology*; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism*; D004781:Environmental Exposure; D007306:Insecticides / Q000633:toxicity*; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000503:physiopathology; D019636:Neurodegenerative Diseases / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*; D011722:Pyrethrins / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013378:Substantia Nigra / Q000187:drug effects / Q000503:physiopathology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin