Koh P O, Kwak S D, Kang S S, Cho G J, Chun S Y, Kwon H B, Choi W S
Department of Histology, College of Veterinary Medicine, Gyeongsang National University, Chinju, Kyungnam, Korea.
Mol Reprod Dev. 2000 Apr;55(4):379-86. doi: 10.1002/(SICI)1098-2795(200004)55:4<379::AID-MRD4>3.0.CO;2-N.
Pituitary adenylate cyclase activating polypeptide (PACAP) was isolated from ovine hypothalamus and known to stimulate the production of cAMP in anterior pituitary cells. In the recent report, the expression of PACAP was detected in preovulatory follicles, and treatment with PACAP stimulated the production of progesterone and prostaglandin E(2) through the action of AC and PLC pathways in the ovary. PACAP binds to three type receptors. Type I A receptor is coupled to adenylate cyclase (AC) and phospholipase C (PLC) pathways, while type I B and type II receptors are only coupled to AC. Thus, the present study aimed to evaluate the temporal expression of PACAP and its type I A receptor mRNAs in the rat ovary after treatment with pregnant mare's serum gonadotropin and human chorionic gonadotropin (hCG). Northern blot analysis showed that PACAP transcripts were transiently expressed from 3-9 hr after hCG treatment, reaching a maximum at 6 hr. During these time points, PACAP mRNAs were specifically and strongly expressed in granulosa cells and cumulus cells of large preovulatory follicles and interstitial glandular cells. Type I A receptor mRNAs were also transiently expressed in granulosa cells of large preovulatory follicles from 3-9 hr after hCG treatment. PACAP and its type I A receptor mRNAs were expressed in the same preovulatory follicles. These results demonstrate that PACAP acts as an autoregulator or pararegulator through type I A receptor in granulosa cells and cumulus cells of large preovulatory follicles. Thus, we suggest that PACAP may have a critical role in granulosa cells of preovulatory follicles for the preparation of ovulation.
垂体腺苷酸环化酶激活多肽（PACAP）是从绵羊下丘脑分离出来的，已知它能刺激垂体前叶细胞中cAMP的产生。在最近的报告中，在排卵前卵泡中检测到了PACAP的表达，用PACAP处理可通过卵巢中AC和PLC途径的作用刺激孕酮和前列腺素E2的产生。PACAP与三种类型的受体结合。I A型受体与腺苷酸环化酶（AC）和磷脂酶C（PLC）途径偶联，而I B型和II型受体仅与AC偶联。因此，本研究旨在评估用孕马血清促性腺激素和人绒毛膜促性腺激素（hCG）处理后大鼠卵巢中PACAP及其I A型受体mRNA的时间表达。Northern印迹分析表明，PACAP转录本在hCG处理后3-9小时短暂表达，在6小时达到最大值。在这些时间点，PACAP mRNA在大的排卵前卵泡的颗粒细胞和卵丘细胞以及间质腺细胞中特异性且强烈表达。I A型受体mRNA在hCG处理后3-9小时也在大的排卵前卵泡的颗粒细胞中短暂表达。PACAP及其I A型受体mRNA在同一排卵前卵泡中表达。这些结果表明，PACAP通过I A型受体在大的排卵前卵泡的颗粒细胞和卵丘细胞中作为自调节因子或旁调节因子起作用。因此，我们认为PACAP可能在排卵前卵泡的颗粒细胞中对排卵准备起关键作用。
