Impact of different stress paradigms on irritable bowel syndrome: Evidence from clinical and animal studies.

Irritable bowel syndrome is a chronic functional gastrointestinal disorder characterized by recurrent abdominal pain and altered bowel habits, a condition significantly influenced by stress. Based on the brain's perception and response to stressors, stress can be categorized into physical stress and psychological stress. Accordingly, this narrative review focuses on elucidating the effects of different stress paradigms on irritable bowel syndrome. Stress activates the locus coeruleus-norepinephrine system and hypothalamic-pituitary-adrenal axis, contributing to symptom onset and progression. Physically, stress disrupts intestinal homeostasis and promotes low-grade inflammation, leading to the emergence of gastrointestinal symptoms, which typically occur following intestinal infection or in the context of inflammatory bowel disease. Psychologically, stress can trigger mental symptoms such as anxiety and depression, which share a bidirectional causal relationship with irritable bowel syndrome; antidepressants and cognitive behavioral therapy have been shown to be effective in managing irritable bowel syndrome. Early adverse life events may heighten stress sensitivity and increase irritable bowel syndrome risk. Animal models employing psychosocial or physical stressors have demonstrated that stress induces visceral hypersensitivity and brain-gut axis dysregulation through mechanisms including intestinal barrier impairment, mild inflammation, microbiota disruption, and altered neural signaling. These insights support integrated strategies for the prevention and management of irritable bowel syndrome.