Dysfunction of the autonomic nervous system activity is responsible for gastric myoelectric disturbances in the irritable bowel syndrome patients

The pathogenesis of the irritable bowel syndrome (IBS) is still unsolved. Lately most attention has been focused on visceral hypersensitivity related to dysfunction of the autonomic nervous system (ANS). The aim of this study was to evaluate changes in the ANS activity and gastric motility in constipation-predominant IBS patients using the heart rate variability (HRV) and gastric myoelectric activity (EGG) recording. 23 patients (45 +/- 13 yrs) matching Manning criteria and 30 healthy volunteers (47 +/- 5 yrs) participated in the study. EGG and HRV in fasted and fed subjects with fasted serum catecholamine levels were measured in both groups. Fasting IBS pts showed gastric dysrrhythmia (29 +/- 14% vs. 11 +/- 7%), DP was 128.860 +/- 112.000 vs. 46.000 +/- 23.2001 mu V-2, DF 2.37 +/- 0.8 vs. 2.9 +/- 0.2cpm. Feeding (300 kcal) improved dysrrhythmia to 20 +/- 13% vs. 8+/-5%, DP decreased to 74.500+/-57.720 vs. 165.600+/-89.000 mu V-2 and DF increased to 2.53+/-0.7 vs. 3.2+/-0.3cpm. In fasted and fed IBS pts SWC (channels 3-4) was about 60+/-11 vs. 84+/-8% and 68+/-14 vs. 92+/-8% respectively. In IBS pts resting HRV parameters were lower (LF - 650.3 vs. 811.6 ms(2); HF - 508.8 vs. 854.6 ms(2)); with higher LF/HF ratio in IBS patients (1.52 vs. 1.2). The serum fasting level of adrenaline and noradrenaline in IBS pts were higher 1.28+/-0.06 vs. 0.65+/-0.05 nmol/L, and 3.54+/-1.2 vs. 2.89+/-08 nmol/L, p<0.05 respectively. Increased sympathetic drive in IBS pts reflected by high catecholamine levels and LH/HF ratio is responsible for gastric dysrrhythmias and low DF and coupling. Meal has negligible effect on EGG parameters improvement. The ANS dysfunction observed in IBS patients is most probably responsible for disturbances in gastric myoelectric activity presented as gastric dysrrhythmias resulting in gastric emptying delay and dyspeptic symptoms.