Betulinic Acid Mitigates Estrogen Deficiency–Related Femoral Bone Loss: Evidence from an Ovariectomized Rat Model

Objective: Postmenopausal osteoporosis (OP) is characterized by estrogen deficiency–induced bone loss and deterioration of trabecular microarchitecture. Betulinic acid (BA), a natural pentacyclic triterpenoid, has demonstrated antioxidant and osteoprotective properties. This study aimed to evaluate the histopathological effects of BA on femoral bone tissue in ovariectomized rats.Methods: Thirty-two female Wistar albino rats were randomly divided into four groups (n=8): Sham, OVX, BA+OVX (BA administered before OVX), and OVX+BA (BA administered after OVX). BA was given orally at 3 mg/kg/day. Pelvic bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry (DEXA). Serum calcium levels were measured, and femoral bone tissues were evaluated histopathologically for trabecular thinning and loss of connectivity.Results: OVX resulted in a significant reduction in pelvic BMD and marked deterioration of trabecular bone architecture compared with the Sham group. BA administration prior to OVX significantly attenuated OVX-induced bone loss, as evidenced by higher pelvic BMD and preserved trabecular structure compared with the OVX group (p