Neurogastroenterology & Motility. 2017;e13273. wileyonlinelibrary.com/journal/nmo | 1 of 9 https://doi.org/10.1111/nmo.13273 © 2017 John Wiley & Sons Ltd Received: 23 August 2017 | Accepted: 3 December 2017 DOI: 10.1111/nmo.13273 ORIGINAL ARTICLE Antidiarrheal effect of sodium hydrosulfide in diabetic rats: In vitro and in vivo studies M. Saghazadeh-Dezfuli 1 | H. Fanaei 2 | M. K. Gharib-Naseri 2 | S. Nasri 3 | S. A. Mard 1 M. Saghazadeh-Dezfuli and H. Fanaei are first author. 1 Physiology Research Center (PRC), Research Center for Infectious Diseases of Digestive System [Alimentary Tract Research Center], Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 2 Physiology Research Center (PRC), Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran 3 Biology, Payame Noor University, Tehran, Iran Correspondence Seyyed Ali Mard, Physiology Research Center (PRC), Research Center for Infectious Diseases of Digestive System [Alimentary Tract Research Center], Department of Physiology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Email: mard-sa@ajums.ac.ir; alimard77@gmail. com Abstract Background: The inhibitory effects of H 2 S on spontaneous contractions of smooth muscles of small, and large intestines well-established but its role in the pathophysiol- ogy of diarrhea has not been identified. Therefore, this study evaluated the role of exogenous H 2 S (NaHS) on diabetic-induced diarrhea and determined mRNA expres- sion of cystathionine β-lyase (CSE) and cystathionine γ-synthase (CBS) in diabetic rats. Methods: In order to evaluate antidiarrheal effect of H 2 S, normal and diabetic rats received NaHS and L-Cysteine and the total number of fecal pellets (FP) determined. The effect of NaHS on intestinal transit ratio (ITR) was also evaluated in diabetic rats. The level of mRNA expressions of CBS and CSE determined in smooth muscles of je- junum, ileum, and colon in normal, and diabetic rats. The effect of NaHS on frequency and tension of spontaneous contractions of smooth muscle strips of colon, ileum, and jejunum were investigated. Key Results: NaHS decreased ITR, total number of FP, frequency and tension of spon- taneous contractions of colon, ileum, and jejunum muscle strips in diabetic rats. The level of mRNA expression of CSE and CBS in diabetic rats were lower than in normal rats. NaHS, and L-Cysteine decreased the number of FP in normal rats. Conclusions & Inferences: These findings showed NaHS effectively controlled diar- rhea in diabetic rats through decreasing the frequency, and tension of spontaneous contraction of smooth muscles of large, and small intestines. The increased frequency and tension of spontaneous contractions of smooth muscles in diabetic rats may be due to down-regulation of H 2 S biosynthesis enzymes. KEYWORDS diabetic, diarrhea, H 2 S, intestinal transit ratio, rat 1 | INTRODUCTION Diabetic diarrhea is a relatively common gastrointestinal disorder in diabetic patients with uncontrolled or poor controlled of blood glucose level. The prevalence of diabetic diarrhea in diabetic patients is 20%. The fecal incontinence and anorectal dysfunction may be due to autonomic neuropathy, bacterial overgrowth, medications, and dietary factors. 1-4 In vitro studies have been shown that H 2 S decrease the frequency and tension of spontaneous contractions of the smooth muscles of gastric fundus, 5 jejunum and colon in rat, mouse and human. 6 A recent report by authors showed that H 2 S is involved in the pathophysiology of diabetic gastroparesis. 7 Recent in vitro studies have shown that the inhibitory effects of H 2 S on spontaneous contractions of smooth muscles of small, and large intestines but its role in the pathophysiology of diarrhea has not