OBJECTIVETo explore the effect of Yigu capsule contained serum on mRNA and protein expression of osteoblast estrogen receptor (ER), for investigating the mechanism of its preventing and treating osteoporosis by means of regulating estrogen.

METHODSOsteoblasts separated from newborn SD rats were cultured, and divided into 3 groups after being passaged, i.e. the drug-serum treated group, the blank serum group and the DMEM medium control group. The relative amount of ERalpha and ERbeta expression were determined with RT-PCR, the affinity (expressed by equilibrium dissociation constant, KD) and number of ER (RT) were analysed by radioligand assay.

RESULTSThe relative amount of ERbeta mRNA expression were increased in the drug-serum group, with significant difference as compared with that in the other two groups (P < 0.05), but no significant difference among the three groups in ERa mRNA expression (P > 0.05). KD in the drug-serum group showed insignificant difference as compared with that in the other two groups (P > 0.05), but RT increased in the drug-serum group and the difference in the three groups was significant (P < 0.01).

CONCLUSIONDrug-contained serum of Yigu capsule can up-regulate the expression of osteoblast ERbeta mRNA and increase the amount of ERs. Regulating estrogen is possibly one of the mechanisms of Yigu capsule in preventing and treating osteoporosis.