Synchronized Transcutaneous Electroacupuncture Improves High-Fat Meal-Induced Impairment of Gastric Slow Waves and Autonomic Function in Healthy Subjects

Abstract

Purpose: Impairment of gastric slow waves and autonomic function are highly prevalent in functional gastrointestinal disorders (FGIDs). Transcutaneous electroacupuncture (TEA) is a needleless method of electroacupuncture and has been reported to improve gut symptoms, motility, and myoelectrical activity. Synchronized TEA (STEA), a novel method that synchronizes the electrical stimulation with inspiration, has been shown to be more potent than TEA in enhancing vagal activity. The aim of this study was to investigate the effects of STEA at acupoint ST36 on gastric slow waves and autonomic function in healthy subjects with high-fat meal. Methods: Eight healthy subjects (five male, three female, ages 23-46 years, mean age 30 years, BMI 22.4±0.6) were recruited. Each subject came to the lab for five sessions: standard meal control, high-fat meal control, sham stimulation, TEA, and STEA. High-fat meal (fat contributed to 62% of total calories) was served in sham, TEA, and STEA sessions. Each session consisted of a 30-minute baseline, standard or high-fat meal consumption, a 30-minute post-meal period with or without electrical stimulation. Electrogastrogram (EGG) and electrocardiogram (ECG) were recorded during each session. The stimulation parameters are: 2s-on, 3s-off, 0.6ms, 40Hz, 2-10mA. Results: Compared with the standard meal, the high-fat meal reduced normal percentages of gastric slow waves (75.1±10.3% vs. 95.1±8.3%; P<0.05), suppressed dominant power of the slow waves (40.1±4.7 vs. 46.8±5.1; P<0.05), and impaired vagal activity (0.45±0.05 vs. 0.58±0.03; P<0.05). In comparison of sham stimulation, both STEA and TEA enhanced postprandial normal percentages of gastric slow waves (90.1±6.5% and 85.6±7.1% vs. 78.2±9.5%; P<0.05), dominant power (46.1±5.3 and 44.3±5.8 vs. 40.5±4.6; P<0.05) and vagal activity (0.57±0.04 and 0.51±0.05 vs. 0.45±0.07; P<0.05). STEA was more potent than TEA in increasing vagal activity (P<0.05). Although STEA had a tendency to generate better effects than TEA in promoting normal gastric slow waves and dominant power, it did not achieve statistical significance (P>0.05). Conclusion: Both STEA and TEA improves gastric dysrhythmias and autonomic function impairment induced by high-fat meal in healthy subjects. STEA seems to be more potent than TEA in enhancing vagal activity and might be a good therapeutic option for treating FGIDs.