Leptin concentrations in plasma and follicular fluid from prepubertal gilts as influenced by fasting, refeeding and insulin.

none4This study was aimed at verifying whether fasting and refeeding would influence leptin levels both in plasma and follicular fluid from prepubertal gilts and whether insulin affects leptin levels in fasting gilts. In experiment 1, four gilts were fasted for 72 h and then refed. Blood samples were withdrawn during normoalimentation, at the end of fasting and for 4 h after refeeding. All samples were assayed for leptin; alternate samples were assayed for insulin, glucose and non esterified fatty acids (NEFA). Fasting decreased leptin, glucose and insulin levels in plasma while increasing NEFA concentrations. In experiment 2, four gilts were given insulin as a bolus (0.2 IU/Kg body weight) after 68 h of fasting. Blood samples were collected every 15 min around insulin administration and were assayed for leptin, insulin and glucose. This experiment shows that insulin administration increases leptin levels during fasting. In experiment 3, gilts were ovariectomized during normal alimentation (n=4), after 48 h of fasting (n=4) or after 48 h of realimentation following 48 h of fasting (n=4). Leptin levels in both plasma and follicular fluid collected after 48 h of fasting were significantly lower than those observed during normoalimentation or refeeding. In conclusion, a transient increase of insulin during fasting is effective in restoring leptin concentrations; in addition, leptin levels in follicular fluid parallel those in plasma.noneGovoni N.; Galeati G.; Castellani G.; Tamanini C.Govoni N.; Galeati G.; Castellani G.; Tamanini C