Sex‐dependent expression of cytoprotective elements in the kidney in response to a hepatotoxic dose of acetaminophen

Abstract

Acetaminophen (APAP) overdose can cause liver and kidney necrosis. Male mice are known to be more susceptible to APAP hepatotoxicity than females, suggesting that gender‐related genotypic traits play a role in APAP toxicity. Gender‐related differences in susceptibility to APAP nephrotoxicity in mice are also well documented and attributed to differential renal expression of CYP2E1. Recent studies in our laboratory investigated the role of the transcription factor nuclear factor erythroid 2‐related factor 2 (Nrf2), the efflux transporter multidrug resistance‐associated protein 4 (Mrp4), and the drug metabolizing enzyme flavin‐containing mono‐oxygenase 3 (Fmo3) in sex‐dependent susceptibility to APAP‐induced hepatotoxicity in mice. However, the expression and potential role of Nrf2, Fmo3, and Mrp4 in the responsiveness of male and female mouse kidneys to toxic doses of APAP has not been investigated. In the current study, we examined gene expression and protein levels of Nrf2, Mrp4, and Fmo3 in the kidneys of APAP (400 mg/kg) and vehicle treated male and female mice. Plasma alanine aminotransferase (ALT) and blood urea nitrogen (BUN) levels were measured to assess liver and renal damage. Confirmation of tissue damage was made by histopathological analysis. Immunoblots and qRT‐PCR analysis revealed that basal renal Fmo3 gene and protein expression is significantly greater in male than female mice, while Mrp4 expression is higher in females. No differences in basal Nrf2 gene and protein expression were observed among genders. High plasma ALT values and histopathological analysis indicated the presence of hepatotoxicity in both males and females receiving APAP. Renal damage was not evident, as BUN values were within the normal range for both genders and the kidney histology was normal. In response to APAP treatment, no changes in renal expression of Mrp4 or Fmo3 were observed in either gender, consistent with the absence of renal pathology. However, renal Nrf2 gene and protein expression decreased significantly in female mice after APAP dosing. In conclusion, this study documents for the first time the difference in basal renal expression levels of Nrf2 and Fmo3 in male and female mice. Further studies will investigate the expression and regulation of these genes at doses of APAP resulting in renal oxidative stress and toxicity and their potential involvement in the sex‐dependent responses to APAP induced renal damage.Support or Funding InformationSupported by NSF and NIH