Inhibition of the
aryl hydrocarbon receptor (AHR) prevents Western diet-induced
obesity and
fatty liver in C57Bl/6J (B6) male mice. The AHR is a
ligand-activated
nuclear receptor that regulates genes involved in
xenobiotic metabolism and T-cell differentiation. Here, we tested the hypothesis that AHR antagonism would also prevent
obesity and
fatty liver in female mice and that B6 mice (higher-affinity AHR) and congenic B6.D2 mice (lower-affinity AHR) would differentially respond to AHR inhibition. Female and male adult B6 and B6.D2 mice were fed control and Western diets with and without α-naphthoflavone (NF), an AHR inhibitor. A nonlinear mixed-model analysis was developed to project asymptote body mass. We found that
obesity, adiposity, and
liver steatosis were reduced to near control levels in all female and male B6 and B6.D2 experimental groups fed Western diet with NF. However, differences were noted in that female B6.D2 vs B6 mice on Western diet became more obese; and in general, female mice compared with male mice had a greater fat mass to body mass ratio, were less responsive to NF, and had reduced
liver steatosis and
hepatomegaly. We report that male mice fed Western diet containing NF or
CH-223191, another AHR inhibitor, caused reduced
mRNA levels of several liver genes involved in metabolism, including Cyp1b1 and Scd1, offering evidence for a possible mechanism by which the AHR regulates
obesity. In conclusion, although there are some sex- and Ahr allelic-dependent differences, AHR inhibition prevents
obesity and
liver steatosis in both males and females regardless of the
ligand-binding capacity of the AHR. We also present evidence consistent with the notion that an AHR-CYP1B1-SCD1 axis is involved in
obesity, providing potentially convenient and effective targets for treatment.