Bovine ovarian follicular cysts: in vitro effects of lecirelin, a GnRH analogue.

This study investigates the mechanisms of action by which a GnRH analogue may modulate the contractility of the bovine ovarian follicular wall. The in vitro evaluation of the spontaneous basal contractility of bovine preovulatory and cystic follicles was performed, followed by testing the effects of lecirelin, a GnRH analogue, on their basal contractility. Strips of tissue in isolated organ bath were employed. In addition, to better investigate the mechanism of action of lecirelin, the study of the effects of cumulative doses of nifedipine (a calcium channel blocker), phentolamine (an α-adrenoceptor antagonist) and reserpine (an inhibitor of the vesicular up-take of catecholamines) alone and, at the highest doses employed, associated to lecirelin, was set up. The results demonstrate that in basal conditions and after the addition of lecirelin, the strips from preovulatory follicles contract significantly more than strips from cysts. Furthermore, among the patterns of contractility evoked by the three drugs employed, the one induced by nifedipine was the only one unaffected by the addition of lecirelin. The data obtained provide the hypothesis that one of the main mechanisms of action of GnRH, could involve calcium channels.