Effect of pituitary adenylate cyclase-activating polypeptide (PACAP) on progestin biosynthesis in cultured granulosa cells from rat ovary and expression of mRNA encoding PACAP type IA receptor

Abstract

The purpose of this study was to detect the presence of mRNA encoding pituitary adenylate cyclase-activating polypeptide (PACAP) (10, 100 and 1000 ng ml \m=-\ 1). At the end of the incubation period, the incubation media were collected and concentrations of progesterone, 20\g=a\-hydroxypregn-4-en-3-one (20\g=a\-OH-P)H-P) and cAMP were measured. Increasing concentrations of significantly stimulated the production of progestins (progesterone and 20\g=a\-OH-P) and cAMP accumulation in a dose-dependent manner (P < 0.01; ANOVA). This effect was observed in media cultured for 24 and 48 h in both basal and LH-stimulated states. PACAP-38 did not significantly affect the ratio of progesterone: 20\g=a\-OH-P produced by granulosa cells cultured for 24 h in the LH-stimulated state. However, at 1000 ng ml \m=-\1, PACAP-38 significantly decreased the ratio of progesterone to 20\g=a\-OH-P production in granulosa cells cultured for 48 h (P < 0.01). These results suggest that granulosa cells from rat ovary express mRNA encoding PACAP type IA receptor and that PACAP may regulate granulosa cell differentiation and play an important role in the reproductive process. IntroductionPituitary adenylate cyclase-activating polypeptide (PACAP) was first isolated from ovine hypothalamus by its potent activity to stimulate cAMP production in rat anterior pituitary cells (Miyata et al, 1989). PACAP is a novel member of the secretin-glucagon-vasoactive intestinal polypeptide (VIP)-growth hormone releasing hormone (GHRH) family of peptides (Arimura, 1992). The 28 amino terminal residues of PACAP show 68% similarity to VIP. Six amino terminal residues of PACAP are identical to residues in GHRH (Miyata et al, 1989). PACAP occurs as two biologically active, amidated forms, (Miyata et al, 1990). Since its isolation, many studies have described PACAP activity in a variety of tissues (Arimura, 1992; Rawlings and Hezareh, 1996). Although the hypothalamus contains the highest concentration of PACAP, the testes also contain significant amounts. In fact, the total PACAP content of both testes is approximately twice that of the total PACAP content of the extrahypothalamic areas of the brain (Arimura et al, 1991). In the testes and epididymides, PACAP type I receptors are localized to Sertoli cells (Heindel et al, 1992) and the tails of spermatozoa (Shivers et al, 1991). mRNA encoding PACAP is also expressed in rat testes (Kononen et al, 1994

Pituitary adenylate cyclase-activating polypeptide acts synergistically with relaxin in modulating ovarian cell function in rats

“…At the moment, we do not have a clear explanation for this; however, it might be possible that granulosa cells contain different types of PACAP receptors with varying PACAP ligand affinity. A recent study has shown the presence of PACAP type IA receptor in rat granulosa cells (Kotani et al 1998). In addition, the possible presence of PACAP type IB receptor in rat granulosa cells is supported by the work of Heindel et al (1996) who showed that PACAP38 was more effective than PACAP27 in stimulating steroidogenesis and cAMP accumulation in rat granulosa cells.…”

“…Moreover, PACAP may play an autocrine/paracrine role in the ovary. First, PACAP stimulates steroidogenesis and increases cAMP levels in cultured rat granulosa cells (Zhong & Kasson 1994, Heindel et al 1996, Kotani et al 1998. Secondly, PACAP was recently shown to accelerate meiotic maturation in follicle-and cumulus-enclosed rat oocytes (Apa et al 1997).…”

Uterine–ovarian biochemical and developmental interactions to the postimplantation treatment with a butadiene metabolite, diepoxybutane, in pregnant rats

“…Because the localization of PACAP is on the neuronal endings in the uterus [22] and ovary [23,24], it was suggested that PACAP, which is a novel compound with vasoactive intestinal polypeptide-like activity, may be involved in follicular growth and development [24], and may also have a functional role in the gravid uterus and placenta [25]. Other related studies on the rodent ovary also revealed associations between progesterone action and ovarian PACAP secretion [23,26]. Furthermore, the reproductive role of endometrial PACAP in deciduoma formation of rats is apparently progesteronedependent [25].…”

Decrease of Pituitary Adenylate Cyclase Activating Polypeptide and Its Type I Receptor mRNAs in Rat Testes by Ethanol Exposure

“…The mean levels were 154.2 ± 4.3 and 90.3 ± 5.8 in saline-treated and ethanol-treated animals, respectively. DISCUSSION PACAP stimulates cAMP production and steroidogenesis through the PAC 1 receptor, which is coupled to adenylate cyclase and phospholipase C pathways in various steroidogenic cells [12,17,24]. In particular, Rossato et al [22] clearly demonstrated that PACAP stimulates testoster-one secretion in isolated adult Leydig cells through the PAC 1 receptor.…”

“…Besides LH, growth hormone is reported to activate steroidogenic related enzymes and stimulate steroidogenesis in testicular Leydig cells [13]. Pituitary adenylate cyclase activating polypeptide (PACAP), like LH and growth hormone, is known to be associated with steroidogenesis in various cells, including ovarian granulosa cells, corpus luteal cells, and testicular Leydig cells [3,17,22].…”