Objective To observe the effect of electroacupuncture(EA)on ovarian P 450arom and P 450c17α(aromatases)expression and related sex hormone levels in polycystic ovary syndrome(PCOS)rats.Methods Thirty SD rats were randomly divided into normal control group

model group and EA group(10rats/group).PCOS model was made by intragastric administration of letrozole at 1mg/kg per day for consecutive 21days."Guanyuan"(CV 4)and"Zhongji"(CV 3)acupoints were stimulated 20min by EA(2mA

2Hz)

once daily for consecutive 14days.The damp ovarian weight was weighed and the pathological changes of the ovarian tissue were observed after H.E.staining.Ultrastructural changes of the ovarian tissue were observed by transmission electron microscope.Immunohistochemical staining was adopted to detect ovarian follicle granulosa cell P 450arom and follicle membrane cell P 450c17αexpression.The contents of estradiol(E 2)

estrone(E 1)

androstenedione(ASD)

testosterone(T)

follicle-stimulating hormone(FSH)and luteinizing hormone(LH)in the ovarian tissue were measured by ELISA.Results Compared with the normal group

there was a significant increase in the damp weight of both left and right ovarian tissues in the model group(P<0.01).After EA

the ovarian weight was remarkably reduced(P<0.01).Pathological changes of the ovarian tissue such as thickening of the superficial albugineous coat of the ovary

thinning of the granular cell layer

and disappearance of the intraovular oocytes and coronaradiata under light microscope

and mitochondrion swelling

fracture or disappearance of mitochondrial cristae

and enlargement of the endoplasmic reticulum

etc.after modeling were obviously improved in the EA group.In comparison to the control group

the expression of the follicle granulosa cell P 450arom was significantly down-regulated and that of follicle membrane cell P 450c 17αwas significantly upregulated in the model group(P<0.01).After EA intervention these changes were obviously reversed(P<0.05

P<0.01).In the model group

there was a significant increase in the levels of ASD

T and LH in the ovarian tissues(P<0.01)and a marked decrease in the contents of ovarian E 1and E 2(P<0.01)in comparison to the control group.After EA

the ovarian ASD

T and LH levels were notably decreased(P<0.05

P<0.01)and the E 1and E 2levels apparently increased(P<0.01)compared with the model group.Conclusion EA can improve letrozole-induced pathological changes of ovarian morphology and ultrastructure and obviously promote P 450arom expression in the follicle granulosa cell layer and inhibit P 450c17αexpression in the follicle membrane cell layer

as well as regulate sex hormone levels in PCOS rats

facilitating the normal transformation of ovarian androgen to estrogen and restoring the local endocrine disorders.