Blockade of the estrogen receptor alpha-pregnane X receptor axis protects ovariectomized mice against ethanol-induced hepatotoxicity.

Women develop alcohol-associated liver disease (ALD) faster than men at any level of alcohol consumption, implicating estrogen as a contributing factor. However, the precise mechanism remains unknown. Therefore, 12-weeks-old female C57BL/6N mice were subjected to either bilateral ovariectomy (OVX) or sham surgery. After a three-week recovery period, the mice were fed either a 5% ethanol (EtOH)-containing liquid diet or paired-fed control diet for 10 days followed by a single gavage dose of EtOH (5 g/kg, 30% EtOH solution). The mice were examined for serum biochemical parameters, hepatotoxicity, histology, expression of xenobiotic nuclear receptors PXR and CAR, and their target gene mRNAs and proteins in hepatic and perigonadal white adipose tissues (pgWAT). While OVX mice on a control diet significantly gained weight, EtOH significantly increased hepatotoxicity, residual EtOH levels, lipid peroxidation, and oxidative stress in sham-operated mice but not in their OVX counterparts. Additionally, in the livers and pgWAT of the sham mice, EtOH significantly increased the mRNA and/or protein levels of the major estrogen receptor ERα, PXR, CAR, and their target genes, proinflammatory cytokines and chemokines, lipogenic genes, and FGF21 levels, a predictive biomarker for ALD severity in humans, but inhibited NRF2 and its targets genes encoding NQO1 and BHMT. Unexpectedly, all these changes were attenuated in the EtOH-fed OVX mice by the upregulation of NRF2 and aryl hydrocarbon receptor (AhR) and their downstream antioxidant target genes. Together these results suggest the existence of an estrogen-regulated ERα-PXR-NRF2-signaling axis in liver and pgWAT which contributes to sexual dimorphism in ALD.