Ovariectomy reverses the effect of ritonavir in female mice. A) At six weeks of age, female LDL-R null mice were bilaterally ovariectomized and administered ritonavir (15 μg/day) or vehicle (0.01% ethanol) through the drinking water for six weeks. An intact group was included as a control. Mice were weighed at the beginning and at the conclusion of the study. Bars represent the mean +/- SEM, n = 6–8. B) Serum leptin levels were measured by ELISA in ovariectomized female mice treated with ritonavir (15 μg/day) or vehicle (0.01% ethanol) for six weeks. Bars represent the mean +/- SEM, n = 6–8. * = significantly different from vehicle (p < 0.05).