Effect Of Low Calcium Diet And Ovariectomy On Vitamin D Endocrine System In Rats And The Antiosteoporotic Activity Of Erythrina Variegate L. And Ligustrum Lucidum Ait.

In the present thesis the effects of estrogen deficiency induced by ovariectomy (OVX) and/or low calcium diet (LCD) on the bone properties and vitamin D endocrine system in rats, and the osteoprotective effects of the extract of Erythrina variegata L. (EV) and Ligustrum lucidum Ait (FLL), respectively, in OVX rats and the mechanisms of action were evaluated.The results showed that OVX increased the excretion of urinary Ca and LCD elevated the excretion of urinary P. Both of these two factors decreased the bone mineral density (BMD) of cancellous bone and the contents of bone Ca, but had no effects on bone mass in cortical bone. OVX did harm to the material mechanics in the diaphysis of femur, while LCD did not show significant influence on bone biomechanics. Combination of these two factors led to aggravate bone loss. Two-way ANOVA analysis showed that OVX enhanced serum PTH levels and gene expression of renal 1-OHase, while LCD increased serum 1,25(OH)₂D₃ levels, gene expression of renal 1 -OHase and duodenal TRPV-6 and CaBP-9k as well as protein expression of renal 1-OHase and bone VDR.The tests of screening the anti-osteoporosis activity in vitro from plenty of Chinese herbs by MTT showed that EV extract at the concentration of 20μg/ml had good activity of promoting proliferation on rat osteoblast-like cells, UMR106, and the proliferation rate was more than 30%. Then the osteoprotective effects of the extract of EV in OVX rats as postmenopausal osteoporosis model and the mechanisms of action was explored. The results showed that EV (600 mg/kg, 300 mg/kg, i.g.) and FLL (550 mg/kg, i.g.), which were orally administrated to OVX rats for 14 weeks, inhibited significantly urine Ca excretion and high bone turnover, and improved bone mechanical property in OVX rats. Neither of two TCM extracts influenced body weight and uterus weight. EV increased trabecular thickness and area, decreased trabecular separation, and improved microstructure in cancellous by histomorphometric analysis. Further RT-PCR analysis for gene expression and HPLC analysis for serum constitutes indicated that anti-osteoporosis activity of EV may be attributed to the up-regulation of gene expression of...