Antidiarrheal effect of sodium hydrosulfide in diabetic rats: In vitro and in vivo studies.

BACKGROUND: The inhibitory effects of H2 S on spontaneous contractions of smooth muscles of small, and large intestines well-established but its role in the pathophysiology of diarrhea has not been identified. Therefore, this study evaluated the role of exogenous H2 S (NaHS) on diabetic-induced diarrhea and determined mRNA expression of cystathionine ß-lyase (CSE) and cystathionine γ-synthase (CBS) in diabetic rats. METHODS: In order to evaluate antidiarrheal effect of H2 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 jejunum, 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 spontaneous 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 diarrhea 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 H2 S biosynthesis enzymes.

Delayed gastric emptying in diabetic rats caused by decreased expression of cystathionine gamma lyase and H2 S synthesis: in vitro and in vivo studies.

BACKGROUND: This study aimed to evaluate the role of H2 S on gastric emptying rate (GER) and also to determine the effect of gastric distention on mRNA and protein expression of cystathionine ß-lyase (CBS) and cystathionine γ-synthase (CSE) in diabetic-gastroparetic and normal rats. METHODS: Adult normal rats intraperitoneally received either propargylglycine (PAG), L-cysteine or NaHS 30 min prior to GER marker (acetaminophen) to investigate H2 S involvement in GER and the same protocols were performed in diabetes-induced gastroparesis rats. The role of calcitonin gene related peptide (CGRP) neurons in the prokinetic effect of endogenous H2 S on GER was determined. The level of CBS and CSE expressions in response to gastric distention were also determined. The effect of H2 S on frequency and tension of spontaneous contractions of gastric smooth muscle strips was investigated. KEY RESULTS: Our results showed that: (i) H2 S and L-cysteine increased GER in gastroparetic and normal rats. (ii) The increased levels of CSE expression in response to gastric distention in diabetic rats were lower than in normal rats. (iii) PAG inhibited the excitatory effect of capsaicin on GER and on tension of spontaneous contractions of strips. (iv) Hydrogen sulphide increased the frequency and tension of spontaneous contractions of gastric strip muscles in normal and diabetic rats. CONCLUSIONS & INFERENCES: The results showed that delayed GER in diabetic rats can be due to down-regulation of H2 S biosynthesis enzyme, CSE and suggested that a potential prokinetic role for H2 S to treat the delayed gastric emptying in diabetic patients.

Plasticity in the gastric inhibitory innervation after immunization against VIP and vagotomy in the ferret.

Changes in gastric corpus tone have been characterized during two procedures that compromise the major inhibitory innervation of the stomach: immunoneutralization of endogenous vasoactive intestinal polypeptide (VIP) and chronic vagotomy. After both procedures, there was a small but significant increase in intracorpus pressure generated during ramp increases in volume compared with sham immunized controls but not when the procedures were combined in vagotomized immunized animals. Adaptation in the mechanisms controlling corpus tone was most apparent after atropine (100 micrograms/kg) and acute vagal section when tone was low in sham immunized vagotomized and vagotomized immunized animals (4.4 +/- 0.3 and 3.7 +/- 0.8 cmH2O, respectively) and high in immunized and sham immunized animals (6.5 +/- 0.4 and 6.2 +/- 0.5 cmH2O) despite a similar sensitivity to atropine. Corpus responses to low-frequency vagal stimulation were maintained in immunized animals despite the absence of a response to exogenous VIP. We conclude that gastric reservoir function adapts to the loss of the vagal inhibitory innervation by an upregulation of intrinsic reflex pathways controlling myenteric inhibitory neurons, which are non-VIPergic.

Role of nitric oxide and vasoactive intestinal polypeptide in vagally mediated relaxation of the gastric corpus in the anaesthetized ferret.

The roles of VIP and NO in vagally mediated relaxations of the gastric corpus were investigated in the anaesthetized ferret. Intracorpus pressure was recorded manometrically during electrical stimulation of the cervical vagus nerve in three groups of animals: one control group (n = 6), one group treated with an inhibitor of NO synthesis (NG-nitro-L-arginine methyl ester (L-NAME), 1.6 mg/kg); and a third group which had been immunized, prior to the experiment, with a VIP-thyroglobulin conjugate (25 nmol equivalent) in Freund's complete adjuvant. In control animals, following treatment with atropine (100 micrograms/kg), vagal stimulation resulted in a frequency dependent fall in intracorpus pressure with the maximum response at 5 Hz of 2.2 +/- 0.3 cm H2O. Two components of the response could be observed: an initial rapid fall over the first 10 s of stimulation followed by a slower decline over the remainder of the stimulation period. In animals treated with L-NAME (n = 6) the initial rapid response was significantly reduced at all frequencies of stimulation (P < 0.05 - P < 0.005, Mann-Whitney U-test) leaving only the slower second component. In immunized animals (n = 6) the initial rapid response to vagal stimulation was not different from control but the slower second component was significantly reduced at 1 Hz (P < 0.005). We conclude that the response to vagal stimulation appears to consist of two components which can be differentiated using L-NAME and autoimmunization to VIP.

Effect of immunisation against vasoactive intestinal polypeptide on gastric corpus tone and motility in the ferret.

The role of vasoactive intestinal polypeptide in the control of gastric corpus tone and motility was investigated using auto-antibodies to neutralise endogenous vasoactive intestinal polypeptide. Six ferrets were immunised with vasoactive intestinal polypeptide thyroglobulin conjugate in Freund's complete adjuvant which resulted in a significant increase in plasma vasoactive intestinal polypeptide binding activity compared with unimmunised control animals. In acute experiments the level of spontaneous motility in the period immediately after completion of the surgical preparation was 15 times higher in immunised v control animals (p < 0.02). Surprisingly, however, there was no deficit in the ability of the corpus to accommodate fluid. Peak pressure at the end of a 20 ml ramp distension was not different in immunised animals (5.7 (0.6) cm H2O) compared with controls (4.8 (0.3) cm H2O). It is concluded that the non-adrenergic non-cholinergic inhibitory mechanisms regulating corpus tone and motility are different and that vasoactive intestinal polypeptide acts primarily to regulate phasic contractile activity. Alternatively, because of plasticity in the mechanisms controlling corpus tone, the effect of vasoactive intestinal polypeptide may have been superceded during the timecourse of the immunisation procedure.