alpha1-Adrenergic receptor in rat ovary: presence and localization

Noradrenaline modulates ovarian steroidogenesis, stimulates ovulation, and probably promotes follicular development in the ovary. It has been suggested that these effects of noradrenaline are mediated by alpha- and/or beta-adrenergic receptors (ARs) in the ovary. The purpose of the present study was to examine whether alpha(1)-AR is present in the rat ovary. In Western blotting, antibody against alpha(1)-ARs recognized a major protein in the ovary of adult (10-week-old) rats with a molecular weight of 80 kDa, which is similar to that of the alpha(1B)-AR subtype. Immunohistochemistry using this antibody showed that alpha(1)-AR was detected at various sites in the ovary, including large antral follicle, germinal epithelium at the circumference of large antral follicle, corpus luteum, and interstitial tissue. These results confirm that the ovary contains alpha(1)-AR (probably alpha(1B)-subtype), and suggest that this receptor mediates some of the activities of noradrenaline in the regulation of ovarian functions. Furthermore, we found that alpha(1)-AR is present in oocyte of large antral follicle, suggesting that noradrenaline acts on oocyte via this receptor.