We hypothesized that (1) plasma noradrenaline and adrenaline levels were more strongly associated with plasma ACTH levels in response to CRH injection during colorectal distention; and (2) plasma catecholamine and ACTH levels were positively correlated with HRV, and CRH further strengthened this relationship in patients with IBS when compared with controls. This evidence concerns the gene CRH and irritable bowel syndrome.