Autonomic dysfunction in patients with irritable bowel syndrome evidenced by alterations of salivary alpha-amylase secretion.

BACKGROUND: Patients with irritable bowel syndrome (IBS) frequently present with alterations of autonomic activity, especially higher sympathetic activity. Salivary alpha-amylase (sAA) has been implicated as a non-invasive biomarker to reflect the sympathetic activity. Thus, the current study aimed to determine if alterations of sAA secretion could be addressed in IBS patients. METHODS: We recruited twenty-five IBS patients as well as twenty-four age- and sex-matched healthy controls (HCs). Basal and stimulated (by gustatory stimulation with citric acid) saliva samples were collected from each participant, with respective salivary flow rate (SFR) calculated accordingly. Western blotting (WB) was applied to determine the sAA amount by introducing human sAA protein of known quantity. Then the sAA amount ratio was calculated, as expressed by the stimulated sAA amount to basal sAA amount. RESULTS: We observed high variability of the basal and stimulated sAA amount in both groups. An apparently higher prevalence of psychiatric disorders was detected in the IBS group, which was consistent with previous studies. Interestingly, we found elevated basal sAA amount in the IBS patients relative to HCs, which implicated higher sympathetic activities in IBS population. Moreover, we observed blunted sAA response to the gustatory stimulation in the IBS patients, which might be of pathophysiological importance for IBS. CONCLUSION: This is the first attempt to associate sAA secretion with the pathophysiology of IBS. Our results suggest an autonomic dysfunction in IBS patients.