Subtle involvement of the parasympathetic nervous system in patients with irritable bowel syndrome

Abstract

This study comprises assessment of autonomic function in irritable bowel syndrome (IBS) patients, focusing on meal-related changes. In 18 IBS patients (4 males, mean age 45+/-3.0 [SEM] years) and 19 healthy volunteers (6 males, mean age 41+/-3.5 years) blood pressure, heart rate, heart rate variability and muscle sympathetic nerve activity (MSNA) were assessed before, during and after consumption of a standardized meal. In pre- and postprandial phase Valsalva maneuver, cold pressor test (CPT) and deep breathing test were carried out and Visual Analog Scale (VAS) scores for nausea, bloating and pain were obtained. In the IBS group, the meal induced significantly higher VAS scores for pain (P=0.002) and bloating (P=0.02). During food intake, the increase in blood pressure, heart rate and MSNA was equal in patients and controls, but the increase of LF/HF ratio of heart rate variability was significantly higher in the IBS group (median [quartiles] 2.29 [1.14-3.00] versus 0.77 [0.25-1.81]; P=0.03). IBS patients scored lower on pre- and postprandial RRmax/RRmin ratio during deep breathing (DB ratio, P=0.03). The increase in MSNA (burst frequency) in response to CPT tended to be higher in the IBS patients (P=0.07). We conclude that reactivity to food intake, measured as muscle sympathetic nerve activity, is normal in IBS patients. The lower DB ratio and higher LF/HF ratio during food intake in IBS patients is an indication of a reduced parasympathetic reactivity. These results suggest that reduced baseline activity as well as responsiveness of the parasympathetic system could play a role in the pathogenesis of IBS.

Autonomic Function at Rest and in Response to Emotional and Rectal Stimuli in Women with Irritable Bowel Syndrome

“…However, conflicting results exist as to how this imbalance is expressed. Some studies indicate changed sympathetic activity [10][11][12], and/or parasympathetic activity [8,9,[13][14][15][16][17][18], or specific autonomic functional abnormalities only in particular symptom subgroups [19][20][21][22][23].…”

Nicotine enhances inhibition of mouse vagal motor neurons by modulating excitability of premotor GABAergic neurons in the nucleus tractus solitarii

“…Thus activation of nAChRs in DMV-projecting, GABAergic NTS neurons might effectively increase the gain of vagal circuits involved in reflexive inhibition of vagal motor output to the gut (Ferreira et al 2000). Effects of excess, exogenous nicotine might also alter normal brain-gut interactions, impairing autonomic homeostasis and ultimately contributing to symptoms of nicotine toxicity: emesis, dysphagia, gastric stasis, and irritable bowel syndrome (Aggarwal et al 1994;Camilleri 1990;Camilleri and Bharucha 1996;van Orshoven et al 2006). In humans, smoking cessation leads to significant gains in body weight, affecting the efficacy of smoking cessation programs (Nordstrom et al 1999;Pomerleau et al 2000).…”

Evaluation of Left Ventricular Function of Patients with Irritable Bowel Syndrome with Tissue Doppler and 2D Speckle Tracking Echocardiography

“…It has also been reported that IBS can be accompanied to the autonomic nervous system dysfunction in various publications [12][13][14][15][16]. These conditions may cause changes in the electrical activity and contraction problems of the heart.…”