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Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/23/2003 Publication Date: 7/23/2003 Citation: Journal of Animal Science 81:3008-3017, 2003 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 fat synthesis in the adipose tissue. The data in the present study indicate that leptin can directly inhibit fat accumulation in pig fat cells. These data also demonstrate leptin functions to promote the partitioning of energy away from fat accretion within porcine adipose tissue, in part by reducing fatty acid incorporation into fat cells. This action of leptin may be useful in a pharmacological approach to reducing fat mass in swine. Technical Abstract: The present study examined whether or not porcine leptin can alter lipid metabolism in porcine adipocytes. Isolated cell cultures were prepared from the stromal vascular (SV) cell fraction of neonatal, porcine subcutaneous adipose tissue. Cultures were differentiated using 2.5% pig serum + 10 nM insulin + 100 nM hydrocortisone. After 7 days of lipid filling, cultures were washed and used for experiments. Acute experiments assessed 1-14C-palmitate metabolism in cultures exposed to porcine leptin (0 to 1000 ng/mL) for 4 h. Chronic experiments used cultures incubated with 0-1000 ng porcine leptin/ml for 44 h prior to measurements of 1-14C-palmitate metabolism. A third experiment determined if chronic leptin treatment alters lipoprotein lipase activity. Acute leptin treatment inhibited palmitate esterification (p<0.05). Chronic exposure to leptin (1000 ng/ml) increased palmitate oxidation (36%) and reduced total lipid synthesis (up to 42%) (p<0.05). Lipoprotein lipase activity was not affected by chronic leptin treatment (p>0.05). These data indicate that leptin promotes partitioning of fatty acids away from lipid accretion within porcine adipose tissue by stimulating fatty acid oxidation indirectly and inhibiting fatty acid esterification directly. |
