Osteoprotective Effects of Tribulus terrestris L.: Relationship Between Dehydroepiandrosterone Levels and Ca2+-Sparing Effect.

Osteoporosis is a systemic bone disease that is characterized by impairments in bone strength that predispose an individual to a higher risk of fractures. Despite the various etiologies, undoubtedly the most important factors are aging of the population and hypogonadism. Although several therapeutic options are available, pharmacological treatments have some risks. Among these are increases in the incidence of thrombosis, breast cancer, ovarian cancer, endometrial cancer, and muscle injury, among others. Herbal medication may be an alternative for the treatment of osteoporosis. Thus, the aim of this study was to evaluate the therapeutic effect of a standardized extract of Tribulus terrestris L. (TT) on ovariectomy (OVX)-induced bone loss in rats. Female rats were first subjected to OVX and treated with TT (3, 30, and 300 mg/[kg·day]) or furosemide (25 mg/kg) orally for 28 days. Bone densitometry and tibial histology were performed, and acute renal function and testosterone, dehydroepiandrosterone (DHEA), and estradiol levels were assessed. Prolonged treatment with TT stimulated bone mass gain in all ovariectomized animals, raising bone mass to levels that were similar to sham-operated rats. DHEA levels significantly increased in TT-treated rats. The TT group also had lower calcium (Ca²⁺) excretion that OVX control and furosemide-treated rats. Finally, the histopathological analyses showed the maintenance of bone turnover in all TT-treated groups. Overall, the results indicate that the standardized extract of T. terrestris exerted a bone-protective effect by increasing bone mineral density. This activity may be at least partially attributable to an increase in serum DHEA levels and a Ca²⁺-sparing effect.