Objective: To investigate the effect of electroacupuncture(EA) on dysfunction of hypothalamus-pituitary-ovary axis(HPOA) in ovariectomized(OVX) rats so as to explore the neuroendocrine mechanism of acupuncture in the treatment of woman perimenopausal syndrome.Methods: Forty-eight female SD rats(180-(200 g)) were randomized into OVX

OVX+EA

normal control(NC) and EA groups with 12 cases(6 cases used for immunohistochemical study and the other 6 for real-time PCR) in each group.EA((3 Hz)

(2 mA)) was applied to "Guanyuan"(RN 4)

"Zhongji"(RN 3)

"Sanyinjiao"(SP 6) and bilateral "Zigong"(EX-CA 1) for(30 min)

once daily and continuously for 3 days.Radioimmunoassay(RIA) was used to detect blood luteinizing hormone(LH) and estrin(E)2 contents

and real-time reversed transcription polymerase chain reaction(RT-PCR) and immunohistochemistry were utilized for assaying expression of prolactin-releasing peptide(PrRP) and PrRP mRNA in the medulla oblongata and hypothalamus.Results: Comparison of NC

EA

OVX and OVX+EA groups showed that serum E_2 contents of OVX and OVX+EA groups were significantly lower than that of NC group

while serum LH contents of OVX and OVX+EA groups significantly higher than that of NC group(P<0.01

0.05)

and no significant differences were found between NC and EA groups in these two indexes(P>0.05).Compared with OVX group

serum LH level was markedly lower and serum E_2 level markedly higher in OVX+EA group(P<0.05).In comparison with NC group

the number of PrRP immunoreaction(PrRP-ir) positive neurons in nucleus tractus solitarii(NTS) and ventral lateral reticular nucleus(VLRN) and the relative optical density(OD) of bed nucleus of the stria terminalis(BST) in OVX group

and that in NTS in OVX+EA group were markedly fewer(P<0.01)

while compared with OVX group

PrRP-ir positive neurons of NTS and VLRN were significantly more and the OD value of PrRP-ir positive fibers of BST was significantly higher in OVX+EA group(P<0.01

0.05).The relative contents of PrRP mRNA expression(PrRP β-actin) of hypothalamus and medulla oblongata in OVX and OVX+EA groups were significantly lower than those of NC group(P<0.01);comparison between OVX and OVX+EA showed that the relative content of PrRP mRNA expression in the medulla oblongata in the later group was markedly higher than that of the former(P<0.01).No significant differences were found between NC and EA groups in the number of PrRP-ir positive neurons of NTS and VLRN

OD values of the positive fibers of BST and the relative content of PrRP mRNA expression in the hypothalamus and medulla oblongata

and between OVX and OVX+EA groups in the relative content of PrRP mRNA expression in the hypothalamus(P>0.05).Results indicated that in OVX rats

serum E_2 level

PrRP contents in NTS

VLRN and BST

and hypothalamic PrRP expression decreased remarkably and serum LH content increased significantly

while EA could reverse most of the aforementioned changes.Conclusion: PrRP

a new neuropeptide or neurohormone

participates in the effect of EA in normalizing the subnormal function of HPOA in OVX rats

which may be one of the neuroendocrine mechanisms of EA in relieving woman perimenopausal syndrome.