Mechanism Of Electroacupuncture At Zusanli And Neiguan Points Regulating Visceral Hypersensitivity In Rats With Irritable Bowel Syndrome Based On The NF-κB/AhR

Objective: Visceral hypersensitivity is one of the important pathogenesis of IBS,and electroacupuncture is gradually applied to treat IBS,however,its neurophysiological mechanism on visceral hypersensitivity is not well understood.In this study,we investigated the regulation mechanism of visceral hypersensitivity in rats with IBS by electroacupuncture based on NF-κB/AhR pathway.METHODS: After 4 healthy SD pregnant rats gave birth naturally,40 newborn SD rats were randomly divided into a blank group(n=8)and a model preparation group(n=32)using a random number table.A model of visceral hypersensitivity to irritable bowel syndrome was established by "mother-infant separation combined with acetic acid enema".From day 2 after birth,the mother was separated from the baby for 3 h every day until day 21;from day 8 after birth,a central venous catheter with a diameter of 1mm was inserted slowly from the anus of the baby rats,which was lubricated with paraffin wax before insertion,and 0.2 ml of acetic acid at a concentration of 0.5% was given in each enema,and the amount was increased by 0.1 ml every 2 days to 0.5 ml without further increase.The enucleation was stopped until the 21 st day after birth.During the modeling process,3 rats died and 5 rats failed to be modeled.After successful modeling,the model preparation groups were divided into a model group(m group),sham stimulation group(-EA group),and electroacupuncture group(EA group),with 8 rats in each group.The electroacupuncture group was given electroacupuncture to the ipsilateral foot Sanli(ST36)and Neiguan(PC6)points for 30 min/time,once every other day for 4 weeks;the sham stimulation group was acupunctured at non-meridian and non-acupuncture sites with the same frequency as the electroacupuncture group;the model group and the blank group were only grasped daily.After treatment,the visceral sensitivity of rats was assessed by visceral pain threshold(the minimum pressure value when the abdominal wall retreat reflex score was 3),and the levels of serum IL-17 A in rats with irritable bowel syndrome were detected by ELISA,and the protein expression of NF-κB p65,AhR,and CYP1 in colonic tissues of rats with irritable bowel syndrome were detected by Western blot.Results:1.Body mass and Bristol stool score: body mass decreased by 29.4%(p<0.05)and Bristol stool score was significantly upregulated to 6.6(p<0.05)in the model group compared with the blank group,which indicated that the model preparation was meaningful;body mass was significantly upregulated and Bristol stool score was significantly downregulated in the electroacupuncture group compared with the model group,which confirmed that electroacupuncture treatment could alleviate the symptoms of IBS rats.2.Visceral pain threshold: compared with the blank group,the visceral pain threshold of the model group decreased to 0.26 ml(p<0.05),which is an important indicator of successful modeling of IBS rats,implying successful model preparation;compared with the model group,the visceral pain threshold of the electroacupuncture group increased to 0.37 ml(p<0.05),indicating that electroacupuncture can reduce the visceral pain threshold of IBS rats.3.Detection of IL-17 A by ELISA: Compared with the blank group,the expression level of IL-17 A in the model group was increased(p<0.05).Compared with the model group,the expression level of IL-17 A in the electroacupuncture group decreased(p<0.05).4.Western blot: compared with the blank group,the protein expression of NF-κB p65,,AhR,and CY1 were relatively decreased in the model group(p<0.05);compared with the model group,the protein expression of NF-κB p65,AhR and CYP1 were relatively increased in the electroacupuncture group(p<0.05).This is either a possible effect of protein levels of NF-κB p6,5,AhR,and CY1 in rats with irritable bowel syndrome.Conclusion:1.Electroacupuncture at the Foot San Li and Neiguan points can increase body weight,change fecal symptoms and decrease visceral hypersensitivity in IBS rats.2.The mechanism of action of electroacupuncture for IBS may be achieved by activating NF-κB/AhR pathway,up-regulating NF-κB p65,AhR,CYP1 protein expression and down-regulating IL-17 A.