Psychoneuroimmunological Responses to Psychological and Visceral Stress in Irritable Bowel Syndrome

Aims: Little is known about neuroendocrine and immune responses to painful visceral stimuli. Therefore the goal of this study was to analyze psychoneuroimmunological responses to painful rectal distensions and public speaking stress.

Methods: Healthy subjects and irritable bowel syndrome (IBS) patients were studied in two conditions: (1) public speaking stress and (2) painful rectal distensions. State anxiety, acute symptoms, and cardiovascular responses, leukocytes and lymphocyte subsets, plasma levels of cortisol, ACTH and the in vitro production of TNF-a were analyzed.

Results: Blood pressure and heart rate significantly increased in both groups and conditions. Plasma levels of ACTH and cortisol were elevated before the visceral stressor compared to both public speaking and rest conditions. While the number of circulating CD3-CD16+CD56+lymphocytes decreased from 244±153 to 155±80 cells/µl during rectal distensions in healthy subjects, significant increases in CD3-CD16+CD56+lymphocytes from 195±89 to 263±32 were observed in IBS patients. Following public speaking stress, significant increases in the number of cells were observed in both groups. In healthy subjects TNF-a concentration decreased from 104±21 to 78±14 pg/ml following rectal distension, whereas significant increases were observed following public speaking stress.

Conclusion: Painful visceral sensations are influenced by anticipatory stress, but visceral stress evokes immunological responses that differ from responses observed during public speaking stress. IBS patients differ in their stress responses from healthy subjects only during rectal distensions but not during acute psychological stress. This paradigm may constitute a model to study the neuro-immune axis in the pathophysiology of functional gastrointestinal disorders.

Schlüsselwörter

Gastrointestinale Erkrankungen - Psychoneuroimmunologie - Stress