Okada Yohei, Murota-Kawano Akiko, Kakar Sham S, Winters Stephen J
Division of Endocrinology and Metabolism, University of Louisville, Kentucky 40202, USA.
Biol Reprod. 2003 Oct;69(4):1356-61. doi: 10.1095/biolreprod.103.016162. Epub 2003 Jun 11.
Mammalian gonadotropin-releasing hormone (GnRH) I is the neuropeptide that regulates reproduction. In recent years, a second isoform of GnRH, GnRH II, and its highly selective type II GnRH receptor were cloned and identified in monkey brain, but its physiological function remains unknown. We sought to determine whether GnRH II stimulates LH and FSH secretion by activating specific receptors in primary pituitary cultures from male monkeys. Dispersed pituitary cells were maintained in steroid-depleted media and stimulated with GnRH I and/or GnRH II for 6 h. Cells were also treated with Antide (Bachem, King of Prussia, PA), a GnRH I antagonist, to block gonadotropin secretion. In monkey as well as rat pituitary cultures, GnRH II was a less effective stimulator of LH and FSH secretion than was GnRH I. In both cell preparations, Antide completely blocked LH and FSH release provoked by GnRH II as well as GnRH I. Furthermore, the combination of GnRH I and GnRH II was no more effective than either agonist alone. These results indicate that GnRH II stimulates FSH and LH secretion, but they also imply that this action occurs through the GnRH I receptor. The GnRH II receptors may have a unique function in the monkey brain and pituitary other than regulation of gonadotropin secretion.
哺乳动物促性腺激素释放激素（GnRH）I是调节生殖的神经肽。近年来，GnRH的第二种同种型GnRH II及其高选择性II型GnRH受体在猴脑中被克隆和鉴定，但其生理功能仍不清楚。我们试图确定GnRH II是否通过激活雄性猴原代垂体培养物中的特定受体来刺激促黄体生成素（LH）和促卵泡生成素（FSH）的分泌。将分散的垂体细胞置于缺乏类固醇的培养基中，并用GnRH I和/或GnRH II刺激6小时。细胞还用GnRH I拮抗剂Antide（Bachem，普鲁士国王，宾夕法尼亚州）处理，以阻断促性腺激素的分泌。在猴和大鼠垂体培养物中，GnRH II刺激LH和FSH分泌的效果不如GnRH I。在两种细胞制剂中，Antide完全阻断了GnRH II以及GnRH I引起的LH和FSH释放。此外，GnRH I和GnRH II的组合并不比单独使用任何一种激动剂更有效。这些结果表明，GnRH II刺激FSH和LH分泌，但也意味着这种作用是通过GnRH I受体发生的。GnRH II受体在猴脑和垂体中可能具有除调节促性腺激素分泌以外的独特功能。
