Objective: To explore the pharmacological effect and possible meachanism of Yougui Wan on Shen yang deficiency based on hypothalamus-pituitary-gonad axis. Method: The Shen yang deficiency model rats were induced by hydrocortisone. The 60 rats were randomly divided into six groups:the control group

the model group

the methyltestosterone group (0.5 g·kg-1)

low-

middle-and high-dose Yougui Wan groups (0.5

1.0

2.5 g·kg-1). Changes of forced swimming time were tested at 15 and 30 days. Serum levels of testosterone (T) and estradiol (E2) were analyzed by immunobiochemistry

and calmodulin (CaM) mRNA in hypothalamus-pituitary-gonad axis of rats in all groups were determined via quantitative RT-PCR technique after 30 days. Result: The forced swimming time decreased

blood concentration of E2 increased

blood concentration of T decreased

and CaM mRNA levels in rat hypothalamus

pituitary and testicle increased in the model group as compared with the normal group (P<0.05). All above indexes had good improvement in methyltestosterone group and all doses Yougui Wan groups as compared with the model group (P<0.05). Conclusion: Yougui Wan have therapeutical effect on down-regulating the CaM mRNA levels of testical and hypothalamus

regulating the levels of E2 and T

and improving the symptoms of Shen yang deficiency.