Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 18, 2000
Publication Date: N/A
Interpretive Summary: Leptin is a hormone produced by adipose tissue that can affect feeding behavior, animal health and reproduction. Studies in rodents have demonstrated that leptin can reduce fat mass. This experiment was designed to determine if porcine leptin can alter lipid breakdown in the adipose tissue. The data in the present study indicate that leptin can directly promote lipolysis in porcine adipocytes. These data also demonstrate leptin functions to promote the partitioning of energy away from lipid accretion within porcine adipose tissue in part by reducing insulin- mediated inhibition of lipolysis. This action of leptin may be useful in a pharmacological approach to reducing fat mass in swine.
Technical Abstract: Leptin treatment has been demonstrated in numerous studies to alter nutrient partitioning, resulting in a reduction in lipid accretion and accumulation of fat mass. This may be the result of a reduction in lipogenesis or an increase in lipolysis, or a combination of both. The present study was performed to determine if porcine leptin can alter lipolysis in porcine adipocytes. Primary cultures derived from neonatal porcine adipocyte tissue were used to perform this experiment. The stromal vascular cell fraction of the adipose tissue was isolated by collagenase digestion, filtration and subsequent centrifugation. These SV cells were seeded on 25 cm2 tissue culture flasks and permitted to proliferate to confluency in 10% FBS in DMEM/F12 (50:50). Cultures were then induced to differentiate using 2% FBS + 10 mM IBMX + 1 uM Dexamethasone for 48 hours. This medium was then replaced with 5% pig serum + 1 uM insulin to permit the adipocytes to fill with lipid. After 7 days of lipid filling, adipocytes were washed free of this medium, incubated overnight in serum free medium and then replaced with test medium. Test medium contained 100 ng/ml recombinant porcine leptin and 2% pig serum. Cultures were incubated with test medium for 72 hours and then exposed to 0-1 uM isoproteronol pm 10 nM insulin. Leptin could not inhibit basal lipolysis or isoproteronol induced lipolysis. However, leptin increased lipolytic activity of isoproteronol by 31% when in the presence of 10 nM insulin (p<.05). These data demonstrate leptin functions to promote the partitioning of energy away from lipid accretion within porcine adipose tissue in part by reducing insulin mediated inhibition of lipolysis.