Objective To explore the underlying mechanism of acupoint catgut embedding in improving primary dysmenorrhea(PD)in rats based on functional activities of the neuro-endocrine-immune(NEI)network.Methods Forty female rats were equally randomized into blank control

PD model

medication

and acupoint catgut embedding groups.The PD model was established by subcutaneous injection of estradiol benzoate(0.5 mg/rat on the 1 st and 10 th d

and 0.2 mg/rat from 2 ndto 9 th d)and oxytocin(2 U/rat

i.p.).Rats of the medication group were treated by intragastric perfusion of fenbid(0.8 mL/rat

125 mg/100 mL)

once daily for 10 days.The catgut embedding was applied to bilateral"Ciliao"(BL 32)

"Sanyinjiao"(SP 6)and"Guanyuan"(CV 4)before modeling.The body writhing times in 30 minutes were recorded

plasmaβ-endorphin(β-EP)content

and prostaglandin E 2(PGE2)and prostaglandin F 2α(PGF_(2α))contents in the uterus tissue were assayed using ELISA

and the activity of natural killer cell(NK cell)in the spleen tissue was detected using 3-(4

5-dimethyl-2-thiazolyl)-2

5-diphenyl-2-Htetrazolium bromide(MTT)method after isolation and co-culture with K 562 cells.Results The body writhing times were notably more in the model group than in the control group(P<0.01)

and obviously fewer in both medication and catgut embedding groups than in the model group(P<0.01).After modeling

the plasmaβ-EP and uterus PGE2 contents and splenic NK cell activity were significantly decreased(P<0.01)

while the uterus PGF_(2α) content was evidently increased in the model group relevant to the control group(P<0.01).Following the treatment

plasmaβ-EP and uterus PGE2 contents and splenic NK cell activity were considerably up-regulated(P<0.01)

and uterus PGF_(2α) content was markedly down-regulated in both medication and acupoint catgut embedding groups(P<0.01)

suggesting an involvement of the NEI network in catgut embedding-induced improvement of PD.The therapeutic effect of catgut embedment was markedly superior to that of medication in up-regulating splenic NK cell activity(P<0.01).No significant differences were found between the medication and catgut embedding groups in the body writhing times within 30 min

and in the levels of plasmaβ-EP and uterus PGE2 and PGF_(2α)(P>0.05).Conclusion The acupoint catgut embedding has a significant efficacy in relieving PD in rats

which may be related to its effect in up-regulating plasmaβ-EP

uterus PGE2 contents and splenic NK cell activity and in down-regulating uterus PGF2αlevel.