Evidence for a role of KISS-1/GPR54 system in decreased luteinizing hormone (LH) secretion in fasted prepubertal ewes
Short fasting has been shown to suppress luteinizing hormone (LH) secretion in ewes, however, the molecular mechanism underlying this phenomenon is not clear. Based on recent discovery of the crucial role of KiSS-1/GPR54 system in the central control of the GnRH axis, we hypothesized that KiSS-1/GPR54 system was involved in the inhibitory effect of fasting on LH secretion in ewes. To test this hypothesis, we fed six prepubertal ewes subjected to a control diet or fasting 72 h and determined the expression of KiSS-1/GPR54 system in hypothalamus. To further confirm the effects of fasting on the expression of KiSS-1/GPR54 system in hypothalamus as responsible for the suppression of LH secretion in ewes, we also investigated the effect of kisspeptin-10 on the LH secretion in fasted and standard feeding prepubertal ewes. The results show that fasting for 72 h could significantly suppress hypothalamic expression of KiSS-1 and GPR54 gene and LH secretion in prepubertal ewes. In addition, intravenous injection of 1 mg of kisspeptin-10 could significantly increase LH secretion in fasted and standard ewes. These data suggest that the inhibitory effect of fasting on LH secretion of prepubertal ewes is probably via decreasing the expression of KiSS-1/GPR54 system in hypothalamus.
Key words: Fasting, KiSS-1/GPR54 system, hypothalamus, LH, ewes.