Gonadotropin-Independent Regulation of Steroidogenesis in the Fetal Rat Testis(2)

24 Sep

Pituitary adenylate cyclase-activating polypeptide (PA-CAP) is a neuropeptide recently isolated from the ovine hypothalamus . It occurs in two forms, PACAP-38 and PACAP-27, sharing the same N-terminal 27 amino acids. The high degree of sequence homology of these peptides with VIP, peptide histidine isoleucine, secretin, and glucagon (30-68%) suggests its membership in this family of peptides . The highest concentration of PACAP occurs in the central nervous system, and it is found in moderate concentrations in the testis and adrenal medulla and at lower concentrations in the ovary, lung, gastrointestinal tract, and pancreas . Recently, PACAP-like immunoreactivity was detected in the developing germ cells , and it was suggested that PACAP might act as a paracrine or autocrine regulatory factor for the Sertoli and germ cells with a specific function during early spermiogenesis.

To gain new insight into the regulation of fetal testicular steroidogenesis, we have studied the relationships between fetal pituitary and plasma LH concentrations and those of testicular testosterone. We also compared basal and hCG-stimulated rates of testosterone production in vitro at different fetal ages. We provide new evidence that the early active phase of fetal testicular steroidogenesis occurs without gonadotropin action. In addition, we provide evidence that both VIP and PACAP-27 are potential candidates for paracrine factors that regulate early testicular steroidogenesis. You can be sure your pharmacy offers flovent inhaler delivering fast internationally.