Effects of senktide on kisspeptin/neurokinin B/dynorphin peptide mRNA expression and luteinizing hormone secretion in fasted female goats: a pilot study
Keywords:KNDy peptide, metabolic stress, luteinizing hormone, senktide, luteal phase
This pilot study aimed to examine KNDy peptide mRNA (Kiss1/Tac3/Pdyn) expression and to determine the effects of peripheral neurokinin 3 receptor agonist (senktide) administration on the ARC Kiss1 mRNA expression and LH secretion that was affected by fasting condition in intact female goats during the luteal phase of the estrus cycle. During the mid to late luteal phase of the estrus cycle, the goats were randomly divided into three groups; the fed group (n = 2), which was fed ad libitum throughout the experimental period, the fasted group (n = 2) and the fasted + senktide group (n = 2) which were fasted for 96 hours. Blood samples were collected every 10 mins for 7 consecutive hours on the last day of fasting. The brain was collected immediately after the cessation of blood sampling. Senktide (200 nmol) was intravenously administered 2 times, 1 hour after the beginning of blood collection and 30 minutes before brain collection. The serum LH concentration was measured using a competitive inhibition enzyme immunoassay. KNDy peptide mRNA expression was evaluated by RT- qPCR. The ARC Kiss1 and Pdyn expressions level in both fasted and fasted + senktide groups were significantly lower than in the fed group (p<0.05), which corresponded to mean serum LH concentration. There was neither recovery of serum LH concentration nor an increase in Kiss1 mRNA expression in the fasted + senktide group. This pilot study suggests that fasting conditions suppress serum LH concentration by decreasing ARC Kiss1 mRNA expression. Moreover, peripheral senktide administration was unable to recover either Kiss1 mRNA expression or serum LH concentration in fasted goats during the luteal phase of the estrus cycle.