A Naringin- and Icariin-Contained Herbal Formula, Gushukang, Ameliorated Aged Osteoporosis of Aged Mice with High Calcium Intake.

Traditional herbal formula Gushukang (GSK) was clinically applied to treat primary osteoporosis and showed osteoprotective effect in ovariectomized rodent animals and regulatory action on calcium transporters. This study aimed to determine if GSK could ameliorate aged osteoporosis by modulating serum level of calciotropic hormones and improving calcium balance. 18-month-old male mice were orally administered with either GSK (0.38 g/kg body weight) or calcitriol (1 μ g/kg body weight) combined with high calcium diet (HCD, 1.2% Ca) for 60 days. The aged mice fed with normal calcium diet (NCD, 0.6% Ca) were a negative control. Trabecular bone and cortical bone properties as well as calcium balance were determined. Treatment with GSK significantly increased 25(OH)D and 1,25-(OH)₂D levels in serum, moreover, it markedly attenuated trabecular bone micro-architectural deteriorations and elevated trabecular bone mass as well as strengthened cortical bone mechanical properties shown by the increase in maximal bending load and elastic modulus. Calcium balance, including urinary Ca excretion, fecal Ca level and net calcium retention, was remarkably improved by GSK, which up-regulated TRPV6 expression in duodenum and TRPV5 expression in kidney and down-regulated claudin-14 expression in duodenum and kidney. Additionally, 1-OHase and 24-OHase expression was significantly decreased (vs. NCD group) and increased (vs. HCD group), respectively, in kidney of GSK- and calcitriol-treated mice. Taken together, this study demonstrated the ameliorative effects of Gushukang on aged osteoporosis by effectively stimulating vitamin D production and improving calcium balance of aged mice with high dietary calcium supplement. [ABSTRACT FROM AUTHOR]