sodium-bisulfite and Hypersensitivity

The pathogenesis of pain in irritable bowel syndrome (IBS) is poorly understood and treatment remains difficult. The present study was designed to investigate roles of adrenergic signaling and the endogenous hydrogen sulfide producing enzyme cystathionine β-synthetase (CBS) in a previously validated rat model of IBS induced by neonatal colonic inflammation (NCI). Here we showed that NCI-induced visceral hypersensitivity (VH) was significantly attenuated by β2 subunit inhibitor but not by β1 or β3 or α subunit inhibitor. NCI markedly elevated plasma norepinephrine (NE) concentration without alteration in expression of β2 subunit receptors in dorsal root ganglion (DRGs) innervating the colon. In addition, NCI markedly enhanced TRPV1 and CBS expression in the colon DRGs. CBS inhibitor AOAA reversed the upregulation of TRPV1 in NCI rats. In vitro experiments showed that incubation of DRG cells with NE markedly enhanced expression of TRPV1, which was reversed by application of AOAA. Incubation of DRG cells with the H2S donor NaHS greatly enhanced TRPV1 expression. Collectively, these data suggest that activation of adrenergic signaling by NCI sensitizes TRPV1 channel activity, which is likely mediated by upregulation of CBS expression in peripheral sensory neurons, thus contributing to chronic visceral hypersensitivity.

Topics: Adrenergic beta-Agonists; Adrenergic beta-Antagonists; Animals; Behavior, Animal; Cystathionine beta-Synthase; Disease Models, Animal; Ganglia, Spinal; Hypersensitivity; Irritable Bowel Syndrome; Male; Norepinephrine; Patch-Clamp Techniques; Propranolol; Rats; Rats, Sprague-Dawley; Receptors, Adrenergic, beta-2; Signal Transduction; Sulfites; Tacrolimus; TRPV Cation Channels; Up-Regulation

Patients with long-standing diabetes frequently demonstrate gastric hypersensitivity with an unknown mechanism. The present study was designed to investigate roles for nuclear factor-κB (NF-κB) and the endogenous H2S-producing enzyme cystathionine-β-synthetase (CBS) signaling pathways by examining cbs gene methylation status in adult rats with diabetes. Intraperitoneal injection of streptozotocin (STZ) produced gastric hypersensitivity in female rats in response to gastric balloon distention. Treatment with the CBS inhibitor aminooxyacetic acid significantly attenuated STZ-induced gastric hypersensitivity in a dose-dependent fashion. Aminooxyacetic acid treatment also reversed hyperexcitability of gastric-specific dorsal root ganglion (DRG) neurons labeled by the dye DiI in diabetic rats. Conversely, the H2S donor NaHS enhanced neuronal excitability of gastric DRG neurons. Expression of CBS and p65 were markedly enhanced in gastric DRGs in diabetic rats. Blockade of NF-κB signaling using pyrrolidine dithiocarbamate reversed the upregulation of CBS expression. Interestingly, STZ treatment led to a significant demethylation of CpG islands in the cbs gene promoter region, as determined by methylation-specific PCR and bisulfite sequencing. STZ treatment also remarkably downregulated the expression of DNA methyltransferase 3a and 3b. More importantly, STZ treatment significantly enhanced the ability of cbs to bind DNA at the p65 consensus site, as shown by chromatin immunoprecipitation assays. Our findings suggest that upregulation of cbs expression is attributed to cbs promoter DNA demethylation and p65 activation and that the enhanced interaction of the cbs gene and p65 contributes to gastric hypersensitivity in diabetes. This finding may guide the development and evaluation of new treatment modalities for patients with diabetic gastric hypersensitivity.

Topics: Amino Acids; Analysis of Variance; Animals; Area Under Curve; Case-Control Studies; Chromatin Immunoprecipitation; CpG Islands; Cystathionine beta-Synthase; Diabetes Mellitus, Experimental; Disease Models, Animal; DNA (Cytosine-5-)-Methyltransferases; DNA Methyltransferase 3A; DNA Methyltransferase 3B; Dose-Response Relationship, Drug; Electromyography; Enzyme Inhibitors; Female; Ganglia, Spinal; Hypersensitivity; Membrane Potentials; Methylation; Neoplasm Proteins; NF-kappa B; Nucleocytoplasmic Transport Proteins; Oxamic Acid; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley; Sensory Receptor Cells; Stomach Diseases; Sulfites; Up-Regulation