The Establishment of Animal Model of Estrogen Replacement Therapy and the Change of its Serum Nitric Oxide Level

Objective To establish the animal model of estrogen replacement therapy and observe the change of serum nitric oxide (NO)level. Methods Forty female rats were randomly divided into four groups, group A:sham ovariectomy;group B:ovariectomy; group C:ovariectomy with estrogen renlacement therapy (benzoate estradiol, 5 μg im. q2d);group D:ovariectomy with estrogen and progesterone replacement therapy (benzoate estradiol, 5 μg, im. q2d and progesterone, 1mg,im.q2d).Two months later, the serum level of estradiol (E 2), progesterone(P) and NO were determined. Results (1) Significant decrease of serum level of E 2,P and NO were observed in ovariectomied rats comopared with control;(2)Significant increase of serum level of E 2 and NO in group C and group D and serum level of P in group D were observed compared with ovariectomied rats. Conclusion The rats model is able to reflect the state of menopause and estrogen replacement therapy. The change of NO level is according to the change of estradiol level in the serum of rats, suggestting that estrogen may delay the progression of aging mediated by NO.