| [Objective] To observe the effect of acute retrograde gastric electrical stimulation (RGES) on gastric accommodation, release of gut hormones and autonomic nervous function in obese patients.[Methods] Sixteen obese patients (8 men and 8 women) were examined, and the mean BMI was (32.90±2.99) Kg/m2. On the first day, a pair of mucosal gastric electrodes was placed under endoscopy. RGES with pulse trains from a pulse generator was performed at different output energy to assess the effect to various stimulation parameters, and the optimal stimulation parameters were selected. Heart rate variability was recorded before and after RGES. On the second day, the liquid meal load test, the standard solid meal gastric emptying test and food intake test was carried in turn. The acute RGES was given from 30 minutes before the test to the end. The serum was sampled at the beginning and the end of the gastric emptying test, and gut hormones were examined by radio-immunoreactive assay. Heart rate variability was recorded before and after food intake test. On the third day, RGES was replaced with sham RGES. On the fourth day, the electrodes were removed under endoscopy.[Results] The optimal stimulation parameters were selected for every patient, pulse trains 2s-on and 3s-off, amplitude 10mA, frequency 40Hz, pulse width 0.4～10ms. In the liquid meal load test, acute RGES reduced significantly the liquid meal volume when achieving the sense of fullness and the largest liquid meal volume(460±148mL vs.630±219mL, P<0.001; 699±215mL vs.926±295mL, P<0.001). RGES also reduced the gastric accommodation. After re-grouped based on the gender, the liquid meal volume was shown larger in male than that in female.For the half-emptying time in the standard solid meal gastric emptying test, no statistic difference was found for acute RGES when compared with sham RGES (109±26min vs.103±31min,P=0.329); however, marginal differences were observed for gastric retention of solid meal 60 and 120 min after meal (63.37±9.75% vs.59.73±12.87%, P=0.087; 42.22±13.97% vs.38.33±16.87%, P=0.095). The changes of gut hormones induced by acute RGES were not shown as statistically different:insulin(ratio of levels of gut hormones after and before the stimulation,2.55±1.33 vs.1.99±1.26, P=0.185), glucagon-like peptide (1.41±0.66 vs.1.17±0.79, P=0.401),leptin(1.03±0.34 vs.1.08±0.38,P=0.705), ghrelin(0.99±0.11 vs.0.98±0.12, P=0.685), resistin (1.11±0.25 vs.0.99±0.24, P=0.100), obestatin (1.16±0.35 vs.1.13±0.30, P=0.803), and peptide YY (1.56±0.71 vs.1.33±0.61, P=0.181). After re-grouped based on the gender or the median of BMI, the acute RGES promoted the release of glucagon-like peptide in male (1.35±0.71 vs.0.75±0.26, P=0.045), peptide YY in female (1.60±0.69 vs.1.35±0.66, P=0.047), and peptide YY in patients with higher BMI (1.28±0.43 vs.1.03±0.30. P=0.026).Compared to the sham RGES, the acute RGES reduced significantly the food intake in obese patients (689.93±194.84 Kcal vs.963.94±193.83 Kcal, P<0.001). Compared to the fasting resting state, in acute REGS, the LF/(LF+HF) was higher (0.55±0.15 vs.0.62±0.17, P=0.049), and the HF/(LF+HF) was lower (0.45±0.15 vs.0.38±0.17, P=0.049), suggesting that the sympathetic activity was increased and the vagal activity was decreased. After re-grouped based on the median of BMI, the aforementioned changes were only observed in the patients with lower BMI, not those with higher BMI. After re-grouped based on the gender, no changes were shown.[Conclusions] In obese patients, acute RGES reduces significantly the liquid meal volume by the reduction of gastric accommodation, inhibits the gastric emptying of solid meal, increases the sympathetic activity, decreases the vagal activity, and no effect was shown for the release of gut hormones after stimulation.
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