Submitted to: American Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2003
Publication Date: March 20, 2003
Citation: Ramsay, T.G., Bush, J.A., McMurtry, J.P., Thivierge, M.C., Davis, R.A. 2003. Peripheral leptin administration alters hormone and metabolite levels in the young pig [abstract]. Journal of Animal Science. v.81(Suppl. 1):95.
The present study was conducted to determine if peripheral leptin administration can alter GH secretion or feed intake in the young pigs. Six, 6 kg female pigs were fed twice daily at 0800 (3% kg body weight [BW]) and 1500 h (3% kg BW) a diet containing 24% crude protein prior to the study. Animals were fasted overnight and randomly chosen to receive porcine recombinant leptin or saline injections. The dose of leptin given per pig was initially 500 µg/kg BW (L500) in 0.2% BSA as a bolus injection into the carotid artery. Blood samples were obtained from the jugular vein over a 24-h period. Feed was presented to each pig at 1h following leptin injection with subsequent re-weighing of food every 2h. Three days later in a cross-over design, the experiment was repeated with a leptin dose of 100 µg/kg BW (L100) or saline. Three days following this experiment, the experimental protocol was repeated with a leptin dose at 200 µg/kg BW (L200) or saline. Leptin reduced intake in pigs treated with L500 and L200 (P<0.05), but did not affect pigs treated with L100 (P>0.05). Blood glucose was depressed in pigs treated with L500 or L200 (P<0.05). Plasma non-esterified fatty acid (NEFA) remained elevated following feed presentation in pigs treated with L500 or L200(P<0.05). Plasma insulin levels were elevated by feeding in control animals, while insulin levels were depressed in pigs treated with L500 or L200 (P<0.05). In all experiments, leptin injection elevated plasma leptin levels (P < 0.05). Plasma growth hormone (GH) was significantly elevated in pigs treated with L200 (P<0.05) with three peaks apparent at 5, 8, and 13 h post injection. The ability for a single injection of leptin to produce significant changes in hormone and metabolite levels suggests that this peptide has a role in regulation of peripheral metabolism.