Lecirelin (Dalmarelin) Acetate is a synthetic hypothalamic gonadotropin releasing hormone (GnRH) analogue. Lecirelin is a nonapeptide, while the natural compound is a decapeptide; moreover the glycine aminoacid in the 6th position has been substituted by leucine.
Analogs of gonadoliberin (GnRH) are widely used in cattle to synchronize estrus and to induce ovulation, as well as for the treatment of ovarian cysts. The aim of this study was to compare the plasma profiles of LH and progesterone and the follicular dynamics in response to the administration of gonadorelin, lecirelin, or buserelin at the dose recommended to induce ovulation. In addition, the biological response to a half dose of lecirelin was assessed. Twelve healthy Holstein female cows were divided into four sequence groups, according to a Latin square design and received the four treatments during the four periods of the study. Before each period, the estrous cycle was synchronized, and on Day 6 or 7 of the ensuing cycle, the time at which it was most likely to have a dominant follicle, 100 μg of gonadorelin, 25 μg of lecirelin, 50 μg of lecirelin, or 10 μg of buserelin was administered to the cows. Blood samples were regularly collected for up to 4 days after the GnRH administrations.
Picard-Hagen, N., Lhermie, G., Florentin, S., Merle, D., Frein, P., & Gayrard, V. (2015). Effect of gonadorelin, lecirelin, and buserelin on LH surge, ovulation, and progesterone in cattle. Theriogenology, 84(2), 177-183.
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.
Rizzo, A., Cosola, C., Mutinati, M., Spedicato, M., Minoia, G., & Sciorsci, R. L. (2010). Bovine ovarian follicular cysts: in vitro effects of lecirelin, a GnRH analogue. Theriogenology, 74(9), 1559-1569.