Effect of Ghrelin on Plasma Concentration of Gonadotropins in the Female Sannan Goats

Ghrelin is a 28 amino acid peptide which is secreted from the brain and the gastrointestinal system. Recent studies indicate that ghrelin negatively affects energy balance in most mammals. Based on its neuron distributions in hypothalamus, ghrelin coexists with many other neurons. Therefore, ghrelin controls different physiological actions on many different tracts; one of the physiological actions is its effect on gonadotropins secretions. The present investigation was carried out to analyze the potential involvement of ghrelin in the control of gonadotropin secretion. Materials and Methods: Forty female Sannan goats were randomly divided into two groups; each group received daily injections of either 1 or 2 mg ghrelin/kg of body weight (BW) into the jugular vein for ten days. Blood samples were collected every 30 minutes, for two hours after injection of ghrelin, for three days before first injection, till three days after last injection; the samples were assayed for plasma FSH and LH concentration by the Radioimmunoassay (RIA) technique. Results: Injections of 1 and 2 mg ghrelin/kg BW decreased the mean plasma concentration of LH throughout the injection period in all animals in the two groups. The results indicated that ghre-lin significantly decreased mean plasma concen-tration of LH in the female Sannan goats (p<0.01); it however had no significant effect on the mean plasma concentration of FSH. Conclusions: It was concluded that while ghrelin has no effect in the secretion of FSH, it does have an inhibitory effect on LH.