title: Vitamin E co-treatment reduces Aroclor 1254-induced impairment of reproductive neuroendocrine function in Atlantic croaker.
abstract: We have shown previously that exposure of Atlantic croaker to a PCB mixture (Aroclor 1254) results in impaired reproductive neuroendocrine function. In addition, we have identified hypothalamic tryptophan hydroxylase (TPH), the rate-limiting enzyme in serotonin (5-hydroxytryptamine) synthesis, as a target of PCB neuroendocrine toxicity. In order to further elucidate the mechanisms of PCB neurotoxicity, the present study investigated whether PCB-induced decrease in hypothalamic TPH activity resulted from degradation of the enzyme protein. Fish were exposed to Aroclor 1254 in the diet (0.1 mg/100 g body weight (BW)/day) for 30 days. The PCB exposure elicited a significant decrease in hypothalamic TPH protein content, which could be at least partially responsible for the reduced TPH activity. To test whether a similar PCB exposure could cause oxidative damage in croaker hypothalamic tissues, we examined the formation of malondialdehyde (MDA) protein adducts as a marker of lipid peroxidation (LPO). The same dose of PCB increased the MDA-protein adduct formation in the hypothalamus. In a separate experiment, the role of vitamin E, an antioxidant, to prevent or decrease the effect of PCB on hypothalamic TPH activity and gonadal growth was examined. The vitamin E co-treatments (1 and 10 mg/100 g BW/day) with PCB significantly reduced the effects of PCB on TPH activity and gonadal growth. These results suggest possible involvement of oxidative processes in PCB neurotoxicity.
authors.affiliation: Marine Science Institute, The University of Texas at Austin, 750 Channelview Drive, Port Aransas, TX 78373, USA. ikhan@utmsi.utexas.edu
authors.forename: Izhar A
authors.initials: IA
authors.lastname: Khan
authors.forename: Peter
authors.initials: P
authors.lastname: Thomas
mesh_terms: D000818:Animals; D001835:Body Weight; D020111:Chlorodiphenyl (54% Chlorine) / Q000633:toxicity*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D015151:Immunoblotting; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D009490:Neurosecretory Systems / Q000187:drug effects* / Q000502:physiology; D010473:Perciformes / Q000378:metabolism / Q000502:physiology*; D013737:Testis / Q000254:growth & development; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D020111:Chlorodiphenyl (54% Chlorine); D014810:Vitamin E; D008315:Malondialdehyde; D014365:Tryptophan Hydroxylase