Moore Joseph P, Burger Laura L, Dalkin Alan C, Winters Stephen J
Division of Endocrinology and Metabolism, Department of Medicine, University of Louisville, Louisville, Kentucky 40202, USA.
Biol Reprod. 2005 Sep;73(3):491-9. doi: 10.1095/biolreprod.105.041624. Epub 2005 May 25.
The neuropeptide pituitary adenylate cyclase activating polypeptide (ADCYAP 1, or PACAP) has been demonstrated to enhance gonadotropin-releasing hormone (GnRH)-induced gonadotropin secretion and regulate gonadotropin subunit gene expression in cultures of anterior pituitary cells. In the present study, we used in situ hybridization and real-time polymerase chain reaction to examine the expression of Pacap mRNA within the paraventricular nucleus (PVN) and anterior pituitary throughout the estrous cycle of the rat. Levels of luteinizing hormone in serum and pituitary gonadotropin subunit mRNAs were evaluated and displayed cyclic fluctuations similar to those reported previously. Pacap mRNA expression in the PVN and pituitary varied significantly during the estrous cycle, with the greatest changes occurring on the day of proestrus. Pacap mRNA levels in the PVN declined significantly on the morning of diestrus. During proestrus, PVN Pacap mRNA levels significantly increased 3 h before the gonadotropin surge and then declined. Pituitary expression of Pacap mRNA also varied on the afternoon of proestrus with a moderate decline at the time of the gonadotropin surge and a significant increase later in the evening. Expression of the mRNA species encoding the 288 amino acid form of follistatin increased significantly following the rise in pituitary Pacap mRNA, at the termination of the secondary surge in follicle-stimulating hormone beta (Fshb) gene expression. These results suggest that PACAP is involved in events before and following the gonadotropin surge, perhaps through increased gonadotroph sensitivity to GnRH and suppression of Fshb subunit expression through increased follistatin, as previously observed in vitro.
神经肽垂体腺苷酸环化酶激活多肽（ADCYAP 1，或PACAP）已被证明可增强促性腺激素释放激素（GnRH）诱导的促性腺激素分泌，并调节垂体前叶细胞培养物中促性腺激素亚基基因的表达。在本研究中，我们使用原位杂交和实时聚合酶链反应来检测大鼠发情周期中室旁核（PVN）和垂体前叶中Pacap mRNA的表达。评估了血清中促黄体生成素水平和垂体促性腺激素亚基mRNA，并显示出与先前报道相似的周期性波动。PVN和垂体中的Pacap mRNA表达在发情周期中变化显著，最大变化发生在发情前期。在动情后期的早晨，PVN中的Pacap mRNA水平显著下降。在发情前期，促性腺激素激增前3小时，PVN中的Pacap mRNA水平显著升高，然后下降。垂体中Pacap mRNA的表达在发情前期下午也有所变化，在促性腺激素激增时适度下降，在晚上晚些时候显著增加。在垂体Pacap mRNA升高后，在卵泡刺激素β（Fshb）基因表达的二次激增终止时，编码288个氨基酸形式卵泡抑素的mRNA种类的表达显著增加。这些结果表明，PACAP参与了促性腺激素激增之前和之后的事件，可能是通过增加促性腺细胞对GnRH的敏感性以及通过增加卵泡抑素抑制Fshb亚基的表达，如先前在体外观察到的那样。
