The pituitary adenylate cyclase-activating polypeptide (PACAP), isolated for the first time from hypothalamic extracts (Miyata et al. 1989), was localized in some peripheral tissues such as adrenal, gastrointestinal tract, ovary and testis (Arimura et al. 1991, Watanabe et al. 1992, Gathei et al. 1993, Shioda et al. 1994, Kononen et al. 1994). It was previously demonstrated that in the testis PACAP was involved in the steroidogenesis regulation (Lacombe et al. 2006). In our investigation we studied the distribution and the expression of PACAP and its receptors, PAC1, VPAC1 and VPAC2, in the testis of a cartilaginous fish, Torpedo marmorata, by using immunohistochemistry, in situ hybridization, western blot and RT-PCR. We showed that PACAP was highly expressed in Torpedo testis as well as PAC1 and VPAC1, while VPAC2 was found to a lesser extent. Particularly, PACAP and its receptors were found in those cells actively involved in the testis steroidogenesis such as Leydig cells (differently from other vertebrates studied so far), pre-spermatogonia and Sertoli cells within cysts containing pre-spermatogonia and spermiated cysts. Further, we showed that in germ cells PACAP and its receptors were expressed during spermioistogenesis. Our data strongly suggest that PACAP has a role in the male reproductive processes of cartilaginous fish Torpedo marmorata, intervening in steroidogenesis and in the spermioistogenesis.
03 - 07 May 2008
European Society of Endocrinology