Adipokine levels in mice treated with ritonavir. A) Serum leptin levels (left) and adiponectin levels (right) were measured by ELISA in male and female LDL-R null 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). # = significantly different from males (p < 0.05). B) Leptin expression was identified by western immunoblot assay. Total protein was isolated from white adipose tissue from male and female LDL-R null mice treated with ritonavir (15 μg/day) or vehicle (0.01% ethanol) for six weeks. SDS-PAGE and immunoblot with a leptin antibody (#AFP6621299 obtained through the NHPP, NIDDK and Dr. A. F. Parlow) was performed. The relative density of the bands was quantified. C) A representative immunoblot is shown. Recombinant human leptin (rhLeptin) protein was included as a positive control.