Objective To study the effect of transcutaneous auricular vagus nerve stimulation(taVNS) on gastric sensitivity and motility in rats with functional dyspepsia(FD)

so as to explore its underlying mechanism in improving FD. Methods A total of 48 young SD rats were randomly divided into control(n=10)

model(n=9)

taVNS(n=9)

subdiaphragmatic vagus nerve stimulation(SDVNS

n=9) and sham SDVNS(n=7) groups. The FD model was established by gavage of 0.1% iodoa-cetamide+2% glucose

once daily for 6 days. Rats in the taVNS group received taVNS(0.5 mA) of optopoint “Heart” and “Stomach” for 30 min

once daily for 14 days

while rats in the SDVNS group received subdiaphragmatic vagus nerve stimulation through the implanted electrode

and those of the sham SDVNS group received only application of the same electrodes without electrical stimulation. Electromyogram(EMG) of the cervical trapezius muscle(reflecting gastric sensitivity) was recorded before and after intragastric expansion via an air ballon and the gastric emptying rate was calculated for assessing the gastric motility. The contents of acetylcholine(ACh)

nicotinic acetylcholine receptor α7 subunit(α7 nAChR)

interleukin-6(IL-6)

interleukin-1β(IL-1β) and tumor necrosis factor-α(TNF-α) in the duodenum tissue were detected by enzyme-linked immunosorbent assay(ELISA). The expression of nuclear factor kappa B(NF-κB) p65 in the duodenum tissue was determined by Western blot. Results In comparison with the control group

the EMG change rate at intragastric pressure levels of 40

60 and 80 mm Hg

expression of NF-κB p65 protein

and contents of IL-6

IL-1β and TNF-α were significantly increased(P<0.05

P<0.01

P<0.001)

while the gastric emptying rate

ACh and α7 nAChR contents considerably decreased(P<0.05

P<0.001) in the model group. After interventions

the EMG change rate

contents of IL-6

IL-1β and TNF-α

and expression of NF-κB p65 were notably decreased(P<0.05

P<0.01

P<0.001)

and the gastric emptying rate

ACh and α7 nAChR contents obviously increased(P<0.05

P<0.001) in both taVNS and SDVNS groups relevant to the model group. In comparison with the sham SDVNS group

the EMG change rate

contents of IL-6

IL-1β and TNF-α

and expression of NF-κB p65 were notably decreased(P<0.01

P<0.05

P<0.001)

and the gastric emptying rate

ACh and α7 nAChR contents obviously increased(P<0.01

P<0.001) in the both SDVNS and taVNS groups. Conclusion taVNS can reduce gastric sensitivity and promote gastric emptying in FD model rats

which may be closely related to its functions in up-regulating ACh and α7 nAChR contents and inhibiting the activation of NF-κB p65 signaling in the duodenum.