A study of acupoint specificity and mechanism of electroacupuncture intervention on chronic colitis in rats based on PI3K/AKT/mTOR signaling pathway

Objective:This study aimed to elucidate the differences in effects and mechanisms of action of electric-needle therapy at Tian Shu(ST25),Da Chang Shu(BL25),Zu San Li(ST36)and Shang Ju Xu(ST37)acupoints on chronic experimental colitis in rats through the PI3K/AKT/mTOR signaling pathway.Methods:Sixty pathogen-free SD rats were randomly assigned to six groups:the normal,model,Tian Shu(ST25),Da Chang Shu(BL25),Zu San Li(ST36)and Shang Ju Xu(ST37)groups,each with 10 rats.Chronic colitis was induced in rats by combining immunization and local stimulation.After model establishment,electrical needle intervention combined with dispersing wave of 2 Hz/50 Hz with a current intensity of 2 mA once daily for 20 min was applied on acupoints of each group.Subsequently,the inflammation of colonic mucosa and serum levels of inflammatory factors(IL-23,IL-17,IL-10)were observed;ELISA was used to detect mRNA expressions of PI3K,Akt and mTOR in colitic tissues by RT-PCR as well as protein content of p-PI3k/PI3K,p-Akt/Akt,and p-mTOR/mTOR in colitic tissues by Western blotting.Result:Compared with the normal group,the model rats showed a poor general condition,serious damage to the colonic mucosa with a large number of inflammatory cells infiltration.The serum IL-23 and IL-17 expressions were significantly increased(P<0.01),while the serum IL-10 expression was significantly decreased(P<0.01);the mRNA and protein expressions of PI3K,Akt,mTOR and p-PI3K,p-Akt and p-mTOR were significantly increased(P<0.05,P<0.01).Compared with the model group,the pathological slices of rats in each acupoints intervention group showed obvious improvement of colitis inflammatory reaction and tissue damage;the serological levels of IL-23 and IL-17 were significantly reduced(P<0.01),while the serology level of IL-10 was significantly increased(P<0.01);the expressions of PI3K,Akt,mTOR mRNA and p-PI3K,p-Akt,p-mTOR proteins were significantly decreased(P<0.05,P<0.01).Compared with Tian Shu(ST25),Da Chang Shu(BL25),Zu San Li(ST36)groups,the recovery degree of mucosa layers in Shang Ju Xu(ST37)group was closer to that of normal group,and the curative effect was relatively the best;in terms of serological levels of IL-23 and IL-17,the Shang Ju Xu(ST37)group was significantly lower(P<0.05),while the level of IL-10 was significantly higher(P<0.01);the expressions of PI3K,Akt,mTOR mRNA and p-PI3K,p-Akt,p-mTOR proteins were significantly decreased(P<0.05,P<0.01).Conclusion:Results indicate that electrical acupuncture at Tian Shu(ST25),Da Chang Shu(BL25),Zu San Li(ST36)and Shang Ju Xu(ST37)show similar effects in relieving the colitis-induced damage in the mucosa of chronic colitis rats,as well as inflammatory response.Among them,Shang Ju Xu(ST25)has a superior overall effect in treating chronic colitis compared to Tian Shu(ST25),Da Chang Shu(BL25)and Zu San Li(ST36).The mechanism may be related to inhibition of PI3K/Akt/mTOR signaling pathway.