Differential Regulation of Obesity by Swim Training in Female Sham-operated and Ovariectomized Mice

The peroxisome proliferator-activated receptor ${\alpha}$ ($PPAR{\alpha}$) is a nuclear transcription factor that plays a central role in lipid and lipoprotein metabolism. To investigate whether swim training improves obesity and lipid metabolism through $PPAR{\alpha}$ activation in female sham-operated (Sham) and ovariectomized (OVX) mice, we measured body weight, visceral adipose tissue mass, serum free fatty acid at 6 weeks as well as the expression of hepatic $PPAR{\alpha}$ target genes involved in fatty acid oxidation. Swim-trained mice had decreased body weight, visceral adipose tissue mass and serum free fatty acid levels compared to high fat diet fed control mice in both female Sham and OVX mice. These reductions were more prominent in OVX than in Sham mice. Swim training significantly increased hepatic mRNA levels of $PPAR{\alpha}$ target genes responsible for mitochondrial fatty acid ${\beta}$-oxidation, such as carnitine palmitoyltransgerase-1 (CPT-1), very long chain acyl-CoA dehydrogenase (VLCAD), and medium chain acyl-CoA dehydrogenase (MCAD) in OVX mice. However, swim trained female Sham mice did not increase hepatic mRNA levels of $PPAR{\alpha}$ target genes responsible for mitochondrial fatty acid ${\beta}$-oxidation compared to Sham control mice. These results indicate that swim training differentially regulates body weight and adipose tissue mass between OVX and Sham mice, at least in part due to differences in liver $PPAR{\alpha}$ activation.