抄録
Corticotropin-releasing factor (CRF) plays a key role in stress responses such as changes in the endocrine system, autonomic nervous system, behavior and mood. The various actions of CRF are induced through two subtypes of CRF receptor: the CRF-R1 and the CRF-R2, with a higher affinity to CRF-R1 than to CRF-R2. Urocortins 2 (Ucn 2), one of CRF family peptides, is thought to be an endogenous ligand for CRF-R2. We previously demonstrated that Ucn 2 is expressed in the POMC cells of rat pituitary, and that the concentrations of Ucn 2 in culture media of rat anterior pituitary cells are extremely low compared with those of ACTH. We also showed that the mRNA expression and secretion of Ucn 2 in rat anterior pituitary are regulated positively by CRF and negatively by glucocorticoids. Since CRF-R2 has been shown to be expressed on gonadotrophs of the anterior pituitary, we hypothesized that pituitary Ucn 2 may control the expression and secretion of gonadotropin.. Monolayer culture of rat anterior pituitary cells showed that the secretion of LH and FSH was suppressed by Ucn 2. Anti-sauvagine 30 and anti-Ucn 2 antibody (SR6) up-regulated LH and FSH secretion and their β chain mRNA expression. Intraperitoneal injection of SR6 in male rats significantly increased LH and FSH secretion and their mRNA expression compared with those in control rats. These results suggest that pituitary Ucn 2 is involved in the regulatory mechanism of the expression and secretion of gonadotropin through its tonic and inhibitory action on gonadotrophs in a paracrine manner. [J Physiol Sci. 2008;58 Suppl:S38]
