title: Effects of neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment on ovarian development of the sapphire devil, Chrysiptera cyanea.
abstract: In the neuroendocrine system controlling fish reproduction, dopamine (DA) acts as a gonadotropin inhibitory factor and plays a role in regulating gonadal development of certain species. The present study examined the effects of chemical destruction of dopaminergic neurons in the brain on DA production and ovarian development in the sapphire devil Chrysiptera cyanea, a reef-associated damselfish. The avidin-biotin-peroxidase complex method using an antibody against tyrosine hydroxylase (TH), a critical enzyme in the DA synthesis pathway, identified a population of dopaminergic neurons with somata in the anteroventral preoptic nucleus of the diencephalon and fibers terminating in the proximal pars distalis of the pituitary. Maintaining fish in seawater containing 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) at 0.02 and 0.2 µg/mL for 2 days resulted in decreases in DA, 3,4-dihydroxyphenylacetic acid (DOPAC; DA metabolite), and DA metabolic rate in the whole brain. The number of TH-positive neurons in the diencephalon decreased after 0.02 µg/mL MPTP treatment for 2 days. These results suggest that MPTP treatment destroys TH-positive neurons in the diencephalon, thereby decreasing the synthesis and release of DA from the brain. This treatment rescued ovarian development in fish with artificially retracted ovaries during the spawning season. The gonadosomatic index of MPTP-treated fish 5 and 7 days after treatment was significantly higher than that of control fish. Oocytes in the vitellogenic stages were observed in the ovaries of MPTP-treated fish, but not in control fish. These results suggest that DA in the brain drives ovarian development in the sapphire devil.
authors.affiliation: Department of Chemistry, Biology and Marine Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa, 903-0213, Japan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Badruzzaman
authors.forename: Satoshi
authors.initials: S
authors.lastname: Imamura
authors.forename: Yuki
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Taro
authors.initials: T
authors.lastname: Ikegami
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takemura
mesh_terms: D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D017756:Aquaculture / Q000379:methods; D001360:Avidin / Q000378:metabolism; D015153:Blotting, Western / Q000662:veterinary; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D004298:Dopamine / Q000378:metabolism*; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D006735:Horseradish Peroxidase / Q000378:metabolism; D007150:Immunohistochemistry / Q000662:veterinary; D009498:Neurotoxins / Q000494:pharmacology*; D010053:Ovary / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010473:Perciformes / Q000378:metabolism*; D011301:Preoptic Area / Q000166:cytology / Q000187:drug effects
chemical_list: D009498:Neurotoxins; C083986:avidin-horseradish peroxidase complex; D001360:Avidin; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D006735:Horseradish Peroxidase; D004298:Dopamine