Cerasus humilis proanthocyanidins alleviate osteoporosis by regulating renal calcium metabolism

BACKGROUND Postmenopausal osteoporosis is associated with disturbed calcium homeostasis and renal calcium handling. Although Cerasus humilis proanthocyanidins (PA) show anti‐osteoporotic activity, their effects on renal calcium metabolism remain unclear. We hypothesized that C. humilis PA could alleviate ovariectomy (OVX)‐induced bone loss by improving renal calcium reabsorption. RESULTS Compared with untreated OVX rats, 12 weeks of PA treatment increased bone mineral density from 125.5 to 232.8 mg cm −3 and improved trabecular microarchitecture ( P < 0.05). PA reduced β ‐C‐terminal telopeptide and tartrate‐resistant acid phosphatase‐5b levels, increased bone‐specific alkaline phosphatase levels, decreased 24 h urinary calcium excretion, and increased apparent calcium absorption from 50.4% to 87.8% (all P < 0.05). Renal histopathological alterations were attenuated, with increased renal bone morphogenetic protein‐7 and urinary Klotho levels and decreased serum fibroblast growth factor 23 levels. Renal protein expression of transient receptor potential vanilloid 5 (TRPV5) and Calbindin‐D28k increased by 53.0% and 45.6%, respectively ( P < 0.05), with corresponding mRNA upregulation. CONCLUSION C. humilis PA alleviated OVX‐induced bone loss and calcium metabolic disturbances. The effects were associated with reduced urinary calcium loss and increased renal TRPV5 and Calbindin‐D28k expression. Renal calcium handling may therefore contribute to the anti‐osteoporotic effect of C. humilis PA in OVX rats, and the potential as a dietary ingredient for bone health warrants further investigation.