title: Methylmercury inhibits prolactin release in a cell line of pituitary origin.
abstract: Heavy metals, such as methylmercury, are key environmental pollutants that easily reach human beings by bioaccumulation through the food chain. Several reports have demonstrated that endocrine organs, and especially the pituitary gland, are potential targets for mercury accumulation; however, the effects on the regulation of hormonal release are unclear. It has been suggested that serum prolactin could represent a biomarker of heavy metal exposure. The aim of this study was to evaluate the effect of methylmercury on prolactin release and the role of the nitrergic system using prolactin secretory cells (the mammosomatotroph cell line, GH3B6). Exposure to methylmercury (0-100 μM) was cytotoxic in a time- and concentration-dependent manner, with an LC50 higher than described for cells of neuronal origin, suggesting GH3B6 cells have a relative resistance. Methylmercury (at exposures as low as 1 μM for 2 h) also decreased prolactin release. Interestingly, inhibition of nitric oxide synthase by N-nitro-L-arginine completely prevented the decrease in prolactin release without acute neurotoxic effects of methylmercury. These data indicate that the decrease in prolactin production occurs via activation of the nitrergic system and is an early effect of methylmercury in cells of pituitary origin.
authors.affiliation: Laboratório de Neuroquímica Molecular e Celular, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, PA, Brasil.
authors.forename: L A L
authors.initials: LA
authors.lastname: Maués
authors.affiliation: Laboratório de Neuroquímica Molecular e Celular, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, PA, Brasil.
authors.forename: B M
authors.initials: BM
authors.lastname: Macchi
authors.affiliation: Laboratório de Farmacologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, PA, Brasil.
authors.forename: M E
authors.initials: ME
authors.lastname: Crespo-López
authors.affiliation: Laboratório de Interações Celulares, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
authors.forename: L E
authors.initials: LE
authors.lastname: Nasciutti
authors.affiliation: Laboratório de Neuroendocrinologia, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, PA, Brasil.
authors.forename: D L W
authors.initials: DL
authors.lastname: Picanço-Diniz
authors.affiliation: Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil.
authors.forename: J
authors.initials: J
authors.lastname: Antunes-Rodrigues
authors.affiliation: Laboratório de Neuroquímica Molecular e Celular, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, PA, Brasil.
authors.forename: J L M do
authors.initials: JL
authors.lastname: Nascimento
mesh_terms: D000818:Animals; D002417:Cattle; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006736:Horses; D006801:Humans; D008767:Methylmercury Compounds / Q000633:toxicity*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D019335:Nitroarginine / Q000633:toxicity*; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D010911:Pituitary Neoplasms; D011388:Prolactin / Q000378:metabolism*; D051381:Rats
chemical_list: D008767:Methylmercury Compounds; D019335:Nitroarginine; D011388:Prolactin; D019001:Nitric Oxide Synthase