The Protective Effects Of Electro-Acupuncture At Zusanli (ST36) On Intestinal Barrier And Enteric Glial Cells In Rats With Hemorrhagic Shock

Objective:Our precious studies have demonstrated thatelectroacupuncture (EA) at ST36 alleviates the intestinal barrier injury after hemorrhagic shock, and the ptotection is aroused partly by activating the cholinergic anti-inflammatory dependent mechanism and lightening the enteric mucosa injury. But the the mechanism of EA remains unknown and require further study. So we investigated whether electroacupuncture ST36 activates enteric glial cells, and alleviates gut inflammation and barrier dysfunction following hemorrhagic shock.METHODS:Sprague-Dawley rats were subjected to approximately 45% total blood loss and randomly divided into seven groups:(1) sham:cannulation, but no hemorrhage; (2) subjected to hemorrhagic shock (HS); (3) EA:electroacupuncture (EA) ST36 after hemorrhage; (4) VGX/EA:vagotomy (VGX) after hemorrhage, then EA ST36; (5) VGX:VGX after hemorrhage; (6)a-BGT/EA:intraperitoneal injection of a-bungarotoxin (BGT) before hemorrhage, then EA ST36; and (7) α-BGT group:α-BGT injection before hemorrhage. Morphological changes in enteric glial cells (EGCs) were observed by immunofluorescence, and glial fibrillary acidic protein (GFAP); a protein marker of enteric glial activation) was evaluated using reverse transcriptase polymerase chain reaction and western blot analysis. Intestinal cytokine levels, gut permeability to 4-kDa fluorescein isothiocyanate (FITC)-dextran, and the expression and distribution of tight junction protein zona occludens (ZO)-1 were also determined.RESULTS:EGCs were distorted following hemorrhage and showed morphological abnormalities via immunofluorescence, and the processes of EGCs were distorted or out-break. EA ST36 attenuated the morphological changes in EGCs at 6 h, as compared with the VGX, a-BGT and HS groups. EA ST36 increased GFAP expression to a greater degree than in the other groups. EA ST36 decreased intestinal permeability to FITC-dextran (760.5±96.43 ng/mL vs 2466.7±131.60 ng/mL; P<0.05) and preserved ZO-1 protein expression and localization at 6 h after hemorrhage compared with the HS group. However, abdominal VGX and a-BGT treatment weakened or eliminated the effects of EA ST36. EA ST36 reduced tumor necrosis factor-a levels in intestinal homogenates after blood loss, while vagotomy or intraperitoneal injection of a-BGT before EA ST36 abolished its anti-inflammatory effects.CONCLUSION:EA ST36 could activate EGCs and restrain hemorrhage-induced intestinal inflammatory insult, reduce the increasing intestinal permeability, maintain and modulate the ZO-1 protein expression and localization, and protects the intestinal barrier function. Abdominal VGX or intraperitoneal injection of the antagonist of the a7 subunit of the cholinergic nicotinic receptor can weaken or eliminated the effects of EA ST36, which demonstrates the effects of EA ST36 are close relation with an intact vagus nerve and a7nAChR and EGCs.