Sex hormones in the modulation of irritable bowel syndrome

Compelling evidence indicates sex and gender differences in epidemiology,symptomatology,pathophysiology,and treatment outcome in irritable bowel syndrome(IBS).Based on the female predominance as well as the correlation between IBS symptoms and hormonal status,several models have been proposed to examine the role of sex hormones in gastrointestinal(GI)function including differences in GI symptoms expression in distinct phases of the menstrual cycle,in pre-and post-menopausal women,during pregnancy,hormonal treatment or after oophorectomy.Sex hormones may influence peripheral and central regulatory mechanisms of the brain-gut axis involved in the pathophysiology of IBS contributing to the alterations in visceral sensitivity,motility,intestinal barrier function,and immune activation of intestinal mucosa.Sex differences in stress response of the hypothalamic-pituitary-adrenal axis and autonomic nervous system,neuroimmune interac-tions triggered by stress,as well as estrogen interactions with serotonin and corticotropin-releasing factor signaling systems are being increasingly recognized.A concept of"microgenderome"related to the potential role of sex hormone modulation of the gut microbiota is also emerging.Significant differences between IBS female and male patients regarding symptomatology and comorbidity with other chronic pain syndromes and psychiatric disorders,together with differences in efficacy of serotonergic medications in IBS patients confirm the necessity for more sex-tailored therapeutic approach in this disorder.

Stress-induced visceral analgesia assessed non-invasively in rats is enhanced by prebiotic diet

AIM: To investigate the influence of repeated water avoidance stress (rWAS) on the visceromotor response (VMR) to colorectal distension (CRD) and the modulation of the response by a prebiotic diet in rats using a novel surgery-free method of solid-state manometry.METHODS: Male Wistar rats fed a standard diet with or without 4% enzyme-treated rice fiber (ERF) for 5 wk were subjected to rWAS (1 h daily x 10 d) or no stress. The VMR to graded phasic CRD was assessed by intraluminal colonic pressure recording on days 0 (base-line), 1 and 10 (45 min) and 11 (24 h) after rWAS and expressed as percentage change from baseline. Cecal content of short chain fatty acids and distal colonic histology were assessed on day 11. RESULTS: WAS on day 1 reduced the VMR to CRD at 40 and 60 mmHg similarly by 28.9% ± 6.6% in both diet groups. On day 10, rWAS-induced reduction of VMR occurred only at 40 mmHg in the standard diet group (36.2% ± 17.8%) while in the ERF group VMR was lowered at 20, 40 and 60 mmHg by 64.9% ± 20.9%, 49.3% ± 11.6% and 38.9% ± 7.3% respectively. The visceral analgesia was still observed on day 11 in ERF-but not in standard diet-fed rats. By contrast the non-stressed groups (standard or ERF diet) exhibited no changes in VMR to CRD. In standard diet-fed rats, rWAS induced mild colonic histological changes that were absent in ERF-fed rats exposed to stress compared to non-stressed rats. The reduction of cecal content of isobutyrate and total butyrate, but not butyrate alone, was correlated with lower visceral pain response. Additionally, ERF diet increased rWAS-induced defecation by 26% and 75% during the first 0-15 min and last 15-60 min, respectively, compared to standard diet, and reduced rats' body weight gain by 1.3 fold independently of their stress status. CONCLUSION: These data provide the first evidence of psychological stress-related visceral analgesia in rats that was enhanced by chronic intake of ERF prebiotic.