Leptin and Luteinizing Hormone Concentrations in Pigs

North Carolina State University Swine Reproduction Research from 2001. Ovariectomized gilts were either placed on full feed (FF) or restricted to one-third of the full feed amount (RST) for seven days. Blood samples were taken through jugular cannulas every 15 min. for 4 h at the beginning and the end of the seven day period. Then dietary treatments were reversed and seven days later samples were taken as before. Serum concentrations of leptin, insulin and luteinizing hormone (LH) were determined by radioimmunoassay. LH pulse frequency and mean serum leptin and insulin concentrations were lower (P<.01) in RST than FF gilts. Reversal of treatment reversed the patterns of hormone secretion. These results confirm previous observations that feed restriction can inhibit pulsatile LH secretion and suggest this may be related to changes in leptin and/or insulin secretion. In a second experiment, no circadian rhythm in leptin secretion was found in pigs.