Antioxidative peptide from milk exhibits antiosteopenic effects through inhibition of oxidative damage and bone-resorbing cytokines in ovariectomized rats

Objectives Oxidative stress has been implicated as a crucial pathogenic factor in the development of postmenopausal osteoporosis. Milk-derived antioxidative peptides are gaining much attention toward the development of prodrugs for alleviating several human diseases, including osteoporosis. The aim of the present study was to determine whether antioxidant peptides are good candidates for alleviating postmenopausal osteoporosis. Methods In the present study, an ovariectomized (OVX) osteoporotic rat model was used to investigate the protective effects of buffalo milk casein-derived novel peptide VLPVPQK (PEP) against OVX-induced bone loss and the related mechanisms. Results Results of the present study indicated that daily administration of antioxidative peptide PEP at 50 and 100 μg/kg for 8 wk prevents body weight gain, uterine weight loss, and atrophy of endometrial lumen. Moreover, PEP increased femur dry weight, ash weight, bone ash calcium, and serum calcium and phosphorus level. Interestingly, PEP increased bone mineral density and improved trabecular microarchitecture in both femur and tibia of OVX rats. Additionally, PEP increased bone strength, reduced serum bone turnover markers, inhibited bone resorbing cytokines and decreased malondialdehyde level in OVX rat. Furthermore, PEP-elevated serum transforming growth factor-β, increased, reduced glutathione levels, superoxide dismutase, and catalase activity altered by OVX. Conclusion We demonstrated that PEP exhibits antiosteopenic effects via enhancement of antioxidant activity and reduction of bone-resorbing cytokines expression.