抄録
Estradiol is known to control various non-genomic mechanisms through cell-membranes receptors, including GPR30. However, no research has investigated the role of GPR30 in controlling LH secretion from gonadotropes in animals. Using a GPR30-specific agonist, G1, this study aimed to examine the hypothesis that the bovine anterior pituitary expresses GPR30 to mediate the effect of estradiol to suppress the secretion of LH that is induced by GnRH. After both RT-PCR followed by sequence immunohistochemistry had confirmed the presence of GPR30-positive cells in bovine anterior pituitaries, bovine anterior pituitary cells were cultured for 3 days in steroid-free conditions before treatment with 0.01 nM, 0.1 nM, 1 nM, or 10 nM of estradiol, followed by addition of GnRH into the culture media to stimulate LH secretion. Among the 4 estradiol treatment concentrations examined, only treatment with estradiol at a concentration of 0.1 nM estradiol was found to significantly (P < 0.05) inhibit GnRH-stimulated LH secretion from cultured pituitary cells. In contrast, none of the 4 G1 treatment concentrations was found to inhibit GnRH-stimulated LH secretion from the pituitary cells. The results also revealed that pituitary cells treated with estradiol or G1 at a concentration of 10 nM secreted significantly (P < 0.01) more LH than those treated with estradiol or G1 at concentrations of 0.01 nM and 0.1 nM. These results suggest that although the bovine pituitary expresses GPR30, other types of receptors may have more important roles in suppressing effect of low concentrations of estradiol on LH secretion from anterior pituitary cells.
