Plasma Leptin Levels in WT and sst₅ KO Mice Fed a High-Fat Diet Male WT and sst₅ KO mice were fed a high-fat diet (36% wt/wt, 58.4% kcal %) ad libitum and fasted overnight, and blood was collected from retroorbital plexus into heparinized tubes. Leptin levels are expressed as nanograms per milliliter in plasma. Each data point represents a mean of 17–27 animals (±sem); *, P < 0.05; **, P < 0.01.