Plasma profile of fasted WT and KO mice. Plasma hormones and lipids from male WT (black circles, n = 5) and male KO mice (grey circles, n = 5) were measured after 5 h of fasting. In KO mice, leptin levels were 0.14 ± 0.14 ng/ml, with 3 of the 5 KO mice having undetectable levels of leptin. TG, NEFA, Chol, and PL were normal in mutant mice. *P < 0.05 using a Mann-Whitney rank sum test.