Methyldopa reduces plasma bile acid concentrations in a murine model of estrogen-induced cholestasis

Bile acids (BAs) are steroidal molecules with endocrine and exocrine functions, eliminated primarily via bile. Intrahepatic cholestasis of pregnancy (ICP) features elevated maternal BA concentrations linked to adverse perinatal outcomes. Hypertensive disorders of pregnancy, often managed with methyldopa, co-occur with BA dysregulation, yet the impact of methyldopa on BA homeostasis is unclear. We examined methyldopa in a murine model of estrogen-induced cholestasis. Female C57BL/6J mice received ethinylestradiol (10 mg/kg, s.c.) with or without methyldopa (250 mg/kg, p.o.) for 7 days. BA profiles were quantified by LC-MS across plasma, bile, liver, urine, intestine, and feces. Hepatic, ileal, and renal expression of BA-related enzymes/transporters was assessed by RT-qPCR and Western blotting. In estrogen-challenged mice, methyldopa selectively reduced total BA concentrations in plasma and liver without increasing fecal or urinary BA excretion. The lowering coincided with induction of CAR-responsive detoxification/export markers, particularly Cyp2b10 and Abcc3/Mrp3, together with partial restoration of nuclear CAR and reduced p-ERK1/2 normalized to total ERK1/2. Methyldopa also reduced hepatic free cholesterol in cholestatic mice, accompanied by reduced Hmgcr abundance and increased Acat2 expression, indicating altered cholesterol handling that may limit substrate availability for BA synthesis. In conclusion, methyldopa lowered BA plasma concentrations under estrogenic stress consistent with reduced substrate availability for BA synthesis and enhanced detoxification/export. In the context of pregnancy-related BA dysregulation, these findings suggest that methyldopa, when used for hypertensive disorders of pregnancy, does not exacerbate BA accumulation and may selectively attenuate it; this hypothesis warrants clinical evaluation.