Fructus ligustri lucidi extract improves calcium balance and modulates the calciotropic hormone level and vitamin D-dependent gene expression in aged ovariectomized rats

Abstract

Fructus ligustri lucidi (FLL) is a widely used herb in China that is classically included in antiaging formulas for the treatment of age-related symptoms. Our laboratory previously showed that FLL could regulate calcium balance in young ovariectomized (OVX) rats. In the present study, we aimed to determine whether FLL could regulate calcium balance in aged OVX rats and to study the potential mechanisms that mediate its action in vivo. Aged OVX rats were orally administered an ethanol extract of FLL and its vehicle and fed with diets containing different levels of calcium [low calcium diet (LCD), 0.1% Ca; medium calcium diet (MCD), 0.6% Ca; and high calcium diet (HCD), 1.2% Ca] for 12 weeks. Significant reductions in urinary and fecal calcium excretion were found in the FLL-treated animals, resulting in a significant induction of calcium retention in rats fed with the MCD and HCD. FLL treatment significantly increased the serum 1,25-dihydroxyvitamin D3 level and slightly decreased the serum parathyroid hormone level in OVX rats fed with the MCD and HCD. When OVX rats were challenged by LCD, the inductions of serum parathyroid hormone and 1,25-dihydroxyvitamin D3 were decreased by FLL administration. FLL treatment significantly up-regulated duodenal vitamin D receptor and calcium transport protein 1 mRNA expression in rats fed with the HCD. FLL treatment reduced the expression of renal vitamin D receptor and 25-hydroxyvitamin D-24-hydroxylase mRNA in OVX rats fed with the LCD and MCD. Twelve weeks of FLL treatment could reduce calcium loss, modulate the parathyroid hormone-vitamin D axis, and increase vitamin D-dependent calcium transport in aged OVX rats, suggesting that FLL might be useful as an alternative medicine for improving calcium balance in postmenopausal women.