Objective To observe the effect of acupoint catgut embedding on the expression of nucleotide-binding oligomerization domain(NOD)-like receptor protein 3(NLRP3)inflammasome

interleukin(IL)-1βand IL-18 in the uterine tissue of primary dysmenorrhea(PD)rats

so as to explore its underlying mechanisms in improving PD.Methods Forty female SD rats were randomly divided into control

model

acupoint catgut embedding and medication groups(n=10 in each group).The PD model was established by subcutaneous injection of Estradiol Benzoate(0.5 mg/rat on the 1 st and 10 thday

and 0.2 mg/rat from 2 nd to 9 th day)and Oxytocin(2 U/rat

i.p.).The catgut embedding was applied to bilateral"Sanyinjiao"(SP6)and"Guanyuan"(CV4)on the 1 st and 5 th day after modeling.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 body writhing times in 30 min were recorded.The histopathological changes of the uterine were observed by H.E.staining.Western blot was used to detect the expression of NLRP 3

caspase-1

IL-1βand IL-18 in uterine tissues.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<0.05

P<0.01).After modeling

the rats' endometrium was extensively exfoliated and got swelling

the histopathological score and the expression levels of NLRP3

caspase-1

IL-1βand IL-18 proteins in the uterus tissue were evidently increased in the model group relevant to the control group(P<0.01).Following the treatment

the degree of endometrial exfoliation and edema of the uterus tissue was lightened

the pathological score was significantly reduced(P<0.01)

and the expression levels of caspase-1

IL-1βand IL-18 protein in uterus tissue were markedly decreased in both acupoint catgut embedding and medication groups(P<0.01

P<0.05).The NLRP3 protein expression was significantly decreased in the acupoint catgut embedding group compared with that in the model group(P<0.01).The therapeutic effect of acupoint catgut embedding was significantly superior to that of medication in reducing writhing times and down-regulating expression of NLPR3 protein(P<0.01).No significant differences were found between catgut embedding and medication in histopathological score

and expression levels of caspase-1

IL-1β and IL-18 proteins(P>0.05).Conclusion The acupoint catgut embedding can significantly alleviate the symptoms and pathological damage in PD rats

which may be related to its effect in inhibiting the activation of NLRP3 inflammasome in the uterine tissue.