Failure of short-term feed restriction to affect luteinizing hormone and leptin secretion or subcutaneous adipose tissue expression of leptin in the prepuberal gilt.

摘要

Previously we reported that 24-h fast increased serum non-esterified fatty acids (NEFA) concentrations, and decreased leptin pulse frequency, but not mean serum leptin concentrations in the OVX prepuberal gilt. The present study was conducted to determine if short-term feed restriction in the prepuberal gilt would reduce BF gene transcript expression, pulsatile LH secretion and serum leptin concentrations. OVX prepuberal gilts 79+or-4 kg BW were control fed 3 kg (CF; n=6) or feed restricted (RST; 33% of CF diet; n=6) for 8 d to determine the effects of RST on leptin and LH secretion, metabolism, leptin, Ob-rb and transcription factor expression in BF. Blood samples were collected on day 8 and BF on day 9. RST gilts lost BW (-2.5 vs. +8.2 kg; SE=0.6 kg; P<0.001) and BF (-3 vs. +2 mm; SE=1 mm; P<0.02) compared with CF gilts. Postprandial serum T4 concentrations increased (P<0.04) in CF, but not in RST pigs. Postprandial serum insulin and BHBA concentrations were similar between treatments. A treatment x time interaction was detected for plasma glucose (P<0.02) and NEFA (P<0.04) concentrations. Feed restriction failed to affect leptin or LH secretion except for LH pulse amplitude was greater (P<0.01) in RST gilts. RST failed to affect BF leptin, Ob-rb, AFABP, C/EBP alpha , or PPAR gamma 2 expression. In conclusion, the ability of the prepuberal gilt to maintain energy level in the normal range suggests the prepuberal animal is resistant to moderate reduction in nutrition. Thus, leptin may not play a primary role in the regulation of LH secretion in the prepuberal gilt, but may serve as a metabolic signal reflecting the amount of stored energy, which may be necessary for activation of the reproductive axis during puberal development in the gilt..