Auricular vagal nerve stimulation ameliorates burn‐induced gastric dysmotility via sympathetic‐COX‐2 pathways in rats

Abstract

BACKGROUND & AIMS Severe burn injury has been demonstrated to delay gastric emptying. The aim of this study was to investigate effects and cellular mechanisms of auricular electroacupuncture (AEA) at the acupoints innervated by the auricular branch of vagus nerve (ABVN) on burn-induced gastric dysmotility in rats. METHODS Propranolol (β-adrenoceptor antagonist) was injected intraperitoneally after the rats underwent burn injury. All experiments were performed six hours following burn/sham burn injury. AEA was performed at bilateral auricular acupoints for 45min. Electrocardiogram was recorded for 30min. Plasma hormones were measured; cyclooxygenase (COX)-2 expressions in gastric tissue were measured using western blotting and real time RT-PCR. RESULTS 1) Burn injury delayed gastric emptying (P=0.006) and AEA increased gastric emptying by 49% (P=0.045). 2) Burn injury evoked a significant elevation in plasma noradrenaline, which was suppressed by AEA. 3) Burn injury significantly increased protein and mRNA expressions of COX-2 in gastric fundus and antrum. AEA suppressed burn-induced increase in protein expressions but not mRNA expressions of COX-2. CONCLUSIONS Burn injury delays gastric emptying by up-regulating COX-2 attributed to sympathetic overactivity. AEA improves burn-induced delay in gastric emptying, possibly mediated via the sympathetic-COX-2 pathway.

Electroacupuncture via chronically implanted electrodes improves gastric dysmotility mediated by autonomic‐cholinergic mechanisms in a rodent model of functional dyspepsia

“…In the current study we found that “FD” rats showed an elevated plasma NE level that was further increased with under RD; both of these were suppressed with EA. This was consistent with the former study investigating the effect of EA on impaired gastric motility induced by burn injury . Together with the data of HRV, our findings have strongly demonstrated that the ameliorating effect of TEA on gastric slow waves was mediated via the autonomic mechanisms.…”

“…This was consistent with the former study investigating the effect of EA on impaired gastric motility induced by burn injury. 59 Together with the data of HRV, our findings have strongly demonstrated that the ameliorating effect of TEA on gastric slow waves was mediated via the autonomic mechanisms. However, it should be pointed that regarding the measurement of vagal activation, the spectral analysis of HRV and plasma PP showed inconsistent results: EA increased vagal activity based on HRV analysis but showed no effect on vagal activity based on the plasma PP.…”

Current Directions in the Auricular Vagus Nerve Stimulation I – A Physiological Perspective

“…Gastric contraction in rats resulted also in response to aVNS (Gao et al, 2007). aVNS ameliorated burn-induced gastric dysmotility and improved its emptying in rats (Li et al, 2015a). Interestingly, cardiovascular and gastric responses were abolished by blockade of vagal transmission using the muscarinic receptor blocker atropine, which highlights the involvement of VN in both responses and in aVNS (Gao et al, 2007).…”

Metabolic Response in Rats following Electroacupuncture or Moxibustion Stimulation

“…The plasma noradrenaline concentration, which acts as indicator of autonomic function, has been reported to be proportional to the sympathetic activities [36]. It is documented that stimulation of the SM acupoints can improve gastric emptying and suppress the cyclooxygenase-2 (COX-2) protein expression in gastric tissues mediated via the sympathetic-COX-2 pathway [37]. Thus, the increased noradrenalin may be due to interaction between the sympathetic system and COX-2 activity.…”