Pregnane X Receptor–Humanized Mice Recapitulate Gender Differences in Ethanol Metabolism but Not Hepatotoxicity

Abstract

Both human and rodent females are more susceptible to developing alcoholic liver disease following chronic ethanol (EtOH) ingestion. However, little is known about the relative effects of acute EtOH exposure on hepatotoxicity in female versus male mice. The nuclear receptor pregnane X receptor (PXR; NR1I2) is a broad-specificity sensor with species-specific responses to toxic agents. To examine the effects of the human PXR on acute EtOH toxicity, the responses of male and female PXRhumanized (hPXR) transgenic mice administered oral binge EtOH (4.5 g/kg) were analyzed. Basal differences were observed between hPXR males and females in which females expressed higher levels of two principal enzymes responsible for EtOH metabolism, alcohol dehydrogenase 1 and aldehyde dehydrogenase 2, and two key mediators of hepatocyte replication and repair, cyclin D1 and proliferating cell nuclear antigen. EtOH ingestion upregulated hepatic estrogen receptor a, cyclin D1, and CYP2E1 in both genders, but differentially altered lipid and EtOH metabolism. Consistent with higher basal levels of EtOH-metabolizing enzymes, blood EtOH was more rapidly cleared in hPXR females. These factors combined to provide greater protection against EtOH-induced liver injury in female hPXR mice, as revealed by markers for liver damage, lipid peroxidation, and endoplasmic reticulum stress. These results indicate that female hPXR mice are less susceptible to acute binge EtOH-induced hepatotoxicity than their male counterparts, due at least in part to the relative suppression of cellular stress and enhanced expression of enzymes involved in both EtOH metabolism and hepatocyte proliferation and repair in hPXR females.

Role of the Pregnane X Receptor in Binge Ethanol-Induced Steatosis and Hepatotoxicity

“…Similarly, in a previous study, three binge doses of EtOH (6 g/kg, every 12 hours) also failed to induce ALT activity (Abdelmegeed et al, 2013). In contrast with our findings, concomitant with increased LPO, serum ALT activity was significantly increased in male PXR-humanized mice after the same dose of acute EtOH (4.5 g/kg) was administered (Spruiell et al, 2015). Taken together, these findings are consistent with previous studies demonstrating the hepatotoxic effects of EtOH-induced activation of Cyp2b10 due to increased oxidative stress and suppression of EtOH-metabolizing enzymes (Chen et al, 2011;Koga et al, 2016;Wang et al, 2017).…”

“…The EtOH L3K assay kit for quantitative measurement of EtOH concentration (Sekisui Diagnostics P.E.I. Inc., Charlottetown, PE, Canada) was used according to the manufacturer's instructions as described previously (Spruiell et al, 2015). The reaction is based on the enzymatic conversion of EtOH by alcohol dehydrogenase (ADH) to acetaldehyde and NADH.…”

“…Furthermore, binge EtOH administration to mice produced behavioral abnormalities and changes in blood EtOH concentration (BEC), recapitulating some of the changes in human binge drinkers (Carson and Pruett, 1996). Acute EtOH exposure to both humans and rodent models also produced steatosis, lipid peroxidation (LPO), and mitochondrial dysfunction (Meagher et al, 1999;Shukla et al, 2013;Spruiell et al, 2015). Compared with chronic EtOH exposure, relatively little is known regarding the molecular mechanisms of binge EtOHinduced hepatotoxicity.…”

TNFAIP8 regulates autophagy, cell steatosis, and promotes hepatocellular carcinoma cell proliferation

“…Liver tissue extracts were homogenized and prepared as described previously 21 . The rationale for the sample size was based on our published reports 21,22 indicating that 4-6 mice are needed to detect a significant difference in triglyceride accumulation between the experimental groups and their littermate control, with alpha error of 0.05 and power of test of 0.8. Therefore, a sample size of 4-6 is often sufficient to detect changes in lipid metabolism, and steatosis in both chronic EtOH and the HFD models we used in this report.…”

Pregnane X receptor promotes ethanol-induced hepatosteatosis in mice

“…The EtOH L3K assay kit for quantitative measurement of EtOH concentration (Sekisui Diagnostics P.E.I. Inc., Charlottetown, Canada) was used according to the manufacturer's instructions as reported previously (98). The reaction is based on the enzymatic conversion of EtOH by ADH to acetaldehyde and NADH.…”