Introduction Negative emotions are associated with increased and decreased food intake. The mechanisms for these contrasting behaviours are not known. The influence of stress and negative emotion on satiation is likely to occur through multiple physiological mechanisms. Our aim was to evaluate the affect of anxiety on gastric myoelectrical activity (GMA), autonomic nervous system (ANS) gut endocrine and stress neuroendocrine responses to a test meal.
Methods 30 healthy volunteers (26±9 years, 17 M and 13 F) received a 10 min nutrient challenge (50 ml/min, 1.5 kcal/ml) during either neutral or anxiogenic stimuli (electric shock threat) in a randomised order. Satiation symptoms were assessed before and after the challenge. Anxiety VAS scores, ANS, GMA (dominant power, DP, tachygastria), cortisol, gut hormones (ghrelin, glucagon-like peptide (GLP-1) and pancreatic polypeptide (PP)) responses were monitored.
Results Increased anxiety scores confirmed anxiety induction (p=<0.01). During neutral vs anxiety emotion induction (N vs AN), symptom scores for discomfort (1.54±0.37 vs 2.8±0.46 p=<0.05), fullness (5.2±0.5 vs 6.3±0.5, p=<0.05) and belching 1.4±0.4 vs 2.7±0.5, p=<0.01) were significantly higher during anxiety state. The test meal caused increase in prandial and postprandial sympathetic activity compared to baseline (cardiac sympathetic index (CSI) 1.7±0.1 vs 2.3±0.1, and 1.7±0.1 vs 2.4±0.1) and parasympathetic activity to decrease (cardiac vagal tone (CVT) 12.3±1.01 vs 8.4±0.6, 12.3±1.018 vs 7.6±0.6), these changes were more pronounced after anxiety induction compared with neutral state (CSI- p=0.02 and 0.05 and CVT-p=0.001 and 0.01). GMA dominant power increase was blunted (N vs AN, 5.05±0.9 vs −1.4±1.1, p=0.0001) with increased tachygastria (N vs AN, 22.6±17.4 vs 25.2±10.66 p=0.02) during the anxiety state. Anxiety state increased cortisol secretion compared with neutral (%13.71±5.5 vs −9.06±6.19, p=0.003). The test meal increased satiation hormones, GLP-1 and PP (p=0.001 and 0.001), with no differences between the two emotional states. Ghrelin levels decreased after the nutrient challenge, moreover, the degree of drop was more marked during anxiety state (N vs AN, per cent change −59.8±21.2 vs −454.7±169.2 (p=<0.05). Ghrelin levels correlated with CVT (r=0.5, p=0.03) and cortisol responses (r=0.5 and p=0.02).
Conclusion Our results suggest that heightened meal sensations are induced by negative emotional state and result from interplay between autonomic reactivity and gastric myoelctrical responses through interaction with gut hormone responses. Further studies are now required to study the role of these psycho-physiological factors in patients with obesity.
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