Selenium pretreatment alleviates ANIT-induced cholestasis by preserving BSEP expression and hepatic redox homeostasis

Cholestasis is characterized by impaired bile flow and intracellular bile acid accumulation, leading to progressive liver injury driven by oxidative stress, inflammation, and hepatocellular apoptosis. Disruption of canalicular bile acid transport, particularly BSEP dysfunction, represents a central initiating event in cholestatic liver damage. α-Naphthyl isothiocyanate (ANIT) is widely used to model intrahepatic cholestasis; however, the mechanisms underlying selenium-mediated protection remain incompletely defined.

In this study, ANIT-induced cholestasis was established in 60 male Sprague Dawley rats, randomly assigned to five groups: control, ANIT, selenium (0.5 and 1 mg/kg) + ANIT and selenium alone.

ANIT exposure resulted in marked suppression of BSEP, MRP2, and NTCP expression, accompanied by dysregulation of bile acid synthesis and detoxification pathways, as reflected by altered CYP7A1, UGT1A1 and FXR expression levels. These molecular alterations were associated with elevated serum cholestatic markers, enhanced oxidative stress, activation of inflammatory signaling, and increased hepatocellular apoptosis, leading to pronounced histopathological injury and fibrosis. Selenium treatment produced a clearly dose-dependent hepatoprotective effect: the higher dose (1 mg/kg) significantly attenuated ANIT-induced cholestatic damage across nearly all biochemical, molecular, and histopathological parameters, preserving bile acid transporter expression and rebalancing bile acid homeostasis, whereas the lower dose (0.5 mg/kg) produced only partial and, for several key parameters (including serum ALT, AST, GGT, and bilirubin, and oxidative and inflammatory markers), statistically non-significant improvements relative to the ANIT group. This protective effect was accompanied by activation of NRF2/HO-1 and Sirt1 signaling, suppression of TLR4/NF-κB-mediated inflammation, and reactivation of PI3K/AKT/mTOR-dependent pro-survival pathways. Complementary in silico analyses provided structural support by indicating stable interactions of ANIT within the BSEP inhibitory binding pocket.

Overall, these findings demonstrate that selenium, particularly at 1 mg/kg, confers significant pretreatment against ANIT-induced cholestatic liver injury by preserving BSEP/FXR-centered bile acid transport and attenuating downstream oxidative, inflammatory, and apoptotic responses, whereas the lower dose (0.5 mg/kg) showed only limited efficacy. These findings support a prophylactic rather than therapeutic role for selenium in this experimental mode.