tacrolimus and sodium-bisulfide

H2S is produced mainly by two enzymes:cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE), using L-cysteine (L-Cys) as the substrate. In this study, we investigated the role of H2S in gastric accommodation using CBS(+/-) mice, immunohistochemistry, immunoblot, methylene blue assay, intragastric pressure (IGP) recording and electrical field stimulation (EFS). Mouse gastric fundus expressed H2S-generating enzymes (CBS and CSE) and generated detectable amounts of H2S. The H2S donor, NaHS or L-Cys, caused a relaxation in either gastric fundus or body. The gastric compliance was significantly increased in the presence of L-Cys (1 mM). On the contrary, AOAA, an inhibitor for CBS, largely inhibited gastric compliance. Consistently, CBS(+/-) mice shows a lower gastric compliance. However, PAG, a CSE inhibitor, had no effect on gastric compliances. L-Cys enhances the non-adrenergic, non-cholinergic (NANC) relaxation of fundus strips, but AOAA reduces the magnitude of relaxations to EFS. Notably, the expression level of CBS but not CSE protein was elevated after feeding. Consistently, the production of H2S was also increased after feeding in mice gastric fundus. In addition, AOAA largely reduced food intake and body weight in mice. Furthermore, a metabolic aberration of H2S was found in patients with functional dyspepsia (FD). In conclusion, endogenous H2S, a novel gasotransmitter, involves in gastric accommodation.

Topics: Animals; Cystathionine beta-Synthase; Cystathionine gamma-Lyase; Cysteine; Dyspepsia; Eating; Electric Stimulation; Gasotransmitters; Gastric Fundus; Gastric Mucosa; Guanidines; Humans; Hydrogen Sulfide; Male; Mice; Mice, Inbred BALB C; Mice, Transgenic; Microscopy, Fluorescence; Muscle Contraction; Pyridoxal; Signal Transduction; Stomach; Substrate Specificity; Sulfides; Tacrolimus

Hydrogen sulfide (H₂S) functions as a neuromodulator, but whether it modulates visceral pain is not well known. This study was designed to determine the role for the endogenous H₂S producing enzyme cystathionine β-synthetase (CBS) and cystathionine γ-lyase (CSE) in a validated rat model of visceral hyperalgesia (VH).. VH was induced by nine-day heterotypic intermittent stress (HIS). Abdominal withdrawal reflex (AWR) scores were determined by measuring the visceromoter responses to colorectal distension (CRD). Dorsal root ganglia (DRG) neurons innervating the colon were labeled by injection of DiI (1,1'-dioleyl-3,3,3',3-tetramethylindocarbocyanine methanesulfonate) into the colon wall. Patch clamp recording techniques were employed to examine excitability and sodium channel currents of colon specific DRG neurons. Tissues from colon related thoracolumbar DRGs were analyzed for CBS, CSE and sodium channel expression.. HIS significantly increased the visceromotor responses to CRD in association with an upregulated expression of CBS not CSE proteins in colon related DRGs. Administration of O-(Carboxymethyl)hydroxylamine hemihydrochloride (AOAA), an inhibitor of CBS, attenuated the AWR scores in HIS-treated rats, in a dose dependent fashion. In contrast, AOAA did not produce any effect on AWR scores in healthy control rats. AOAA reversed the potentiation of sodium channel current densities of colon specific DRG neurons of HIS rats. To further confirm the role for CBS-H₂S signaling, NaHS was used to mimic the production of H₂S by CBS. Application of NaHS significantly enhanced neuronal excitability and potentiated sodium channel current densities of colon DRG neurons from healthy control rats. Furthermore, AOAA reversed the upregulation of Na(V)1.7 and Na(V)1.8 in colon related DRGs of HIS rats.. Our results suggest that upregulation of CBS expression might play an important role in developing VH via sensitization of sodium channels in peripheral nociceptors, thus identifying a specific neurobiological target for the treatment of VH in functional bowel syndromes.

Topics: Animals; Cystathionine beta-Synthase; Enzyme Inhibitors; Hydrogen Sulfide; Hyperalgesia; Intestinal Diseases; Male; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley; Reflex, Abdominal; Stress, Psychological; Sulfides; Tacrolimus; Up-Regulation; Viscera; Visceral Pain