Hydrogen sulfide-mediated gastric hypersensitivity in diabetic rats

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 818-841-Diabetes Pathophysiology & Complications
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-825
Honghong Zhang*1, Guang-Yin Xu2, Youlang Zhou3 and Ji Hu4
12nd affiliated hospital of Soochow University/ Neuroscience Institute of Soochow University, Suzhou Jiangsu, China, 2Soochow University, Suzhou, Jiangsu, 3Neuroscience Institute of Soochow University, 42nd Affiliated Hospital of Sooch, Suzhou
Background Patients with long-standing diabetes often demonstrate gastric hypersensitivity. We have recently reported that endogenous hydrogen sulfide (H2S) producing enzyme cystathionine-β-synthetase (CBS) played an important role in visceral hypersensitivity. However, the precise mechanism of CBS-H2S signaling pathway in diabetic gastric hypersensitivity remains unknown.
Objective The present study was designed to determine the role for nuclear factor-κB (NF-κB)/CBS-H2S signaling pathways in diabetic gastric hypersensitivity.

Methods Diabetes were induced by a single intraperitoneal injection of streptozotocin (STZ; 65 mg/kg i.p.) in adult female rats. Behavior responses to graded gastric balloon distention will be employed on normal and diabetic rats. Patch clamp recordings were performed in vitro on single gastric-specific DRG neurons acutely isolated from these rats labeled with DiI. Expression of CBS and NF-κB were measured with RT-PCR and western blotting analysis. DNA methylation status were determined by methylation specific PCR and bisulfite sequencing. Recruitment of cbs gene pairs NF-κB was analyzed with chromatin immunoprecipitation (ChIP) assays.
Results (1)Diabetic rats were more sensitive to graded gastric balloon distention 4 weeks after STZ treatment (vs. controls, P<0.01). I.p. injection of CBS inhibitor AOAA could attenuate diabetic gastric hypersensitivity. (2)The excitability of gastric-specific DRG neurons from diabetic rats was increased. 1 week after i.p. injection of AOAA, the neurons' excitability decreased. In addition, NaHS (donor of H2S) could increase the excitability of the gastric-specific DRG neurons of normal rats. (3) CBS and CBS mRNA expression of gastric-specific DRGs in diabetic rats greatly enhanced (P<0.05). And i.p. injection with NF-κB inhibitor PDTC for 1 week reduced upregulation of CBS expression. (4)Cbs gene promoter region of gastric-specific DRGs contained recognition sequence region of NF-κB and it was significantly demethylated in diabetic rats (vs.controls, P<0.05). Results from Chromatin immunoprecipitation(ChIP) assay showed that the intracellular NF-κB could bind specificly to cbs gene promoter region in diabetic rats.

Conclusions Our findings suggest that epigenetic regulation of CBS expression may contribute to epigastric hypersensitivity in diabetic rats and that upregulation of CBS expression may be mediated by NF-κB, thus identifying a potential therapeutic target for the treatment of chronic visceral pain in patients with diabetes.

Nothing to Disclose: HZ, GYX, YZ, JH

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm