Effect of Estrogen on Melanocortin-3 Receptor mRNA Expression in Mouse Pituitary Glands in vivo and in vitro

Abstract

Alpha-melanocyte-stimulating hormone (α-MSH) stimulates prolactin (PRL) release and mammotrope proliferation in mouse anterior pituitary glands. The present study investigated the regulation of melanocortin-3 receptor (MC3-R) mRNA levels in mice using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Relative MC3-R mRNA levels in the anterior lobes of female mice increased between 20 and 45 days of age, and a significant difference in MC3-R mRNA expression between sexes was seen at 45 days. Ovariectomy decreased MC3-R mRNA expression in the female anterior lobes, and estradiol-17β (E₂) treatment increased MC3-R mRNA levels in ovariectomized mouse anterior lobes and cultured anterior pituitary cells. E₂ treatment increased proopiomelanocortin (POMC) mRNA levels in ovariectomized mouse neurointermediate lobes and cultured neurointermediate pituitary cells. On the other hand, E₂ treatment did not affect POMC mRNA expression in mouse anterior lobes or cultured anterior pituitary cells. These results suggest that α-MSH directly stimulates PRL release and mammotrope proliferation through MC3-Rs expressed in mammotropes, while estrogen stimulates MC3-R gene transcription in the anterior pituitary cells and POMC gene transcription in the intermediate lobes. In lactating mice, POMC mRNA levels in the neurointermediate lobes were elevated compared with in non-lactating mice. The present study suggests that α-MSH is involved in augmented PRL secretion by estrogen and during lactation.

Molecular cloning of doublesex and mab-3-related transcription factor 1, forkhead transcription factor gene 2, and two types of cytochrome P450 aromatase in Southern catfish and their possible roles in sex differentiation

“…Dmrt1a, Dmrt1b, Foxl2, Cyp19a, and Cyp19b mRNA levels were expressed relative to that of b-actin in each sample. In our study, b-actin expression was found to be unaffected by the drug treatment, as reported previously for E 2 (Matsumura et al 2004) and TAM (Parte et al 2002).…”

Fisiopatologia do melasma

“…65,83 Investigação dos receptores de estrogênio, na epiderme e nos melanócitos das peles sã e lesada, seria esclarecedora quanto ao papel de hormônios esteróides sexuais, no processo da hiperpigmentação localizada da doença. [84][85][86][87][88] Pesquisa de variantes alélicas do MC1-R, que se expressem diferentemente na pele sã e lesada, poderiam justificar a pigmentação mais efetiva, em certas áreas fotoexpostas, do que em outras. 30,46,89 Cultura de ceratinócitos e melanócitos, de pele sã e com melasma e de populações não acometidas pela doença, sob diferentes regimes de exposição, permitiria um estudo comparativo da expressão de diversos genes para demonstrar as bases do comportamento fenotípico diferente desses grupos de células adjacentes, no mesmo tecido.…”

Functional characterization of the mouse melanocortin 3 receptor gene promoter

“…A previous study indicated that E2 stimulated MC3R gene expression in vivo (Matsumura et al, 2004). Therefore, we investigated the effects of E2 on the Mc3r promoter activity.…”

“…The Mc3r mRNA levels in female pituitaries are higher than in male pituitaries. In mouse pituitaries, in the female mouse anterior pituitary Mc3r mRNA expression is regulated by estrogen (Matsumura et al, 2004). However, it is not clear whether estrogen directly or indirectly regulates Mc3r transcription.…”