Betulinic acid attenuates obesity-associated hepatic steatosis by modulating hepatic lipid handling and bile acid-regulated nuclear receptor signaling in high-fat diet-fed rats.

Obesity-associated hepatic steatosis is a major metabolic consequence of chronic dietary lipid excess and a critical precursor to progressive liver disease. In the present study, we investigated the therapeutic potential of betulinic acid (BA), a plant-derived pentacyclic triterpenoid, in high-fat diet (HFD)-induced hepatic steatosis in rats, with specific emphasis on hepatic lipid handling and bile acid-regulated nuclear receptor signaling. Male Sprague-Dawley rats were fed an HFD for 16 weeks to induce obesity and subsequently treated with BA (40 mg/kg, oral) for 6 weeks. BA treatment markedly improved systemic dyslipidemia and reduced hepatic accumulation of triglycerides, cholesterol, free fatty acids, and phospholipids. These metabolic improvements were accompanied by normalization of serum liver marker enzymes and restoration of bile acid homeostasis. Histopathological assessment demonstrated pronounced attenuation of hepatic steatosis, lobular inflammation, hepatocyte ballooning, and a significant reduction in the Nonalcoholic Fatty Liver Disease Activity Score. At the molecular level, BA suppressed HFD-induced de novo lipogenesis by downregulating sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase while concurrently restoring the expression of apolipoprotein B and microsomal triglyceride transfer protein. In parallel, BA re-established bile acid-regulated nuclear receptor signaling by restoring farnesoid X receptor and small heterodimer partner expression and normalizing cholesterol 7α-hydroxylase levels. Molecular docking analyses further supported these findings by revealing stable interactions of BA with multiple regulators of lipid and bile acid metabolism. Taken together, these findings identify BA as a multitarget metabolic modulator that alleviates obesity-associated hepatic steatosis through coordinated regulation of lipid metabolism and bile acid signaling pathways. SIGNIFICANCE STATEMENT: Obesity-associated hepatic steatosis lacks effective pharmacological interventions that target the underlying metabolic dysregulation. This study demonstrates that betulinic acid exerts hepatoprotective effects by coordinately suppressing hepatic lipogenesis, restoring lipid export, and normalizing bile acid-regulated nuclear receptor signaling in a HFD model. These findings identify betulinic acid as a multitarget metabolic modulator with potential therapeutic relevance for obesity-driven fatty liver disease.