vasoactive-intestinal-peptide and Cholera

We aimed to evaluate the changes of nerve morphology and distribution of neurotransmitters and neuropeptides in the rectum of Shigella flexneri-infected patients and in the duodenum of Vibrio cholerae O1-infected patients. Nerve morphology was observed by transmission electron microscopy. Immunoreactivity of nerve growth factor (NGF), neurotransmitters and neuropeptides in tissues were studied by immunohistochemistry. Ultrastructural analysis of intestinal biopsy revealed persisting axons degeneration throughout the study period in all patients. Regeneration was already evident at the acute stage with marked increase at late convalescence. Both acute shigellosis and cholera were accompanied by increased expression of NGF and histamine and decreased expression of serotonin that was restored at convalescence. Immunoreactivity of vasoactive intestinal peptide (VIP) was increased during acute cholera, whereas in shigellosis VIP- and substance P-immunoreactive nerves appeared at early convalescence. Both shigellosis and cholera induced long-lasting degeneration of enteric neuronal axons, despite the presence of ongoing proliferation and regeneration processes. Neurotransmitters and neuropeptides may play differential roles in invasive and watery diarrhoea.

Topics: Adolescent; Adult; Biopsy; Cholera; Diarrhea; Dysentery, Bacillary; Enteric Nervous System; Histamine; Humans; Male; Middle Aged; Nerve Growth Factor; Neurons; Rectum; Serotonin; Substance P; Ubiquitin Thiolesterase; Vasoactive Intestinal Peptide; Vibrio cholerae O1; Young Adult

Purified cholera enterotoxin (20-50 micrograms) and dialyzed cholera filtrate (50-125 mg) increased net glycoprotein synthetic and secretory rates in rat intestinal epithelium. Specific goblet cell mucin secretion was increased 5- to 10-fold. However, other agents that increase intestinal cAMP and accelerate glycoprotein synthesis did not enhance mucin secretion. This was true for dibutyryl cAMP (10(-3) and 10(-2) M) with or without theophylline (10(-3) M) and isoproterenol (10(-4) M) with or without dibutyryl cAMP (10(-3) M). Hyperosmotic mannitol (450 mosmol/l), which increases fluid secretion but does not affect cAMP, and vasoactive intestinal peptide (2 X 10(-7) M), which increases both fluid secretion and cAMP, both failed to increase mucin secretion, implying that fluid "washout" of mucin adherent to the mucosal surface is not responsible for cholera-induced mucin secretion. Cycloheximide, an inhibitor of cholera diarrhea in vivo (20 mg/kg) or in vitro (1 mM), effectively abolished [3H]leucine incorporation into protein but did not affect cholera-induced mucin secretion. Colchicine (10-50 mg/kg) given to block microtubule assembly was similarly without effect on mucin secretion. These findings suggest that there is a dissociation of electrolyte/fluid and mucin secretory processes and cast doubt on the widely accepted notion that all cholera effects are mediated via the well-known adenylate cyclase-cAMP mechanism.

Topics: Animals; Bucladesine; Cholera; Cholera Toxin; Colchicine; Cyclic AMP; Cycloheximide; In Vitro Techniques; Intestinal Mucosa; Isoproterenol; Mannitol; Mucins; Rats; Theophylline; Vasoactive Intestinal Peptide

In previous reports we have suggested that nervous reflexes are involved in the pathophysiology of cholera secretion and that these nervous reflexes involve a cholinergic synapse and a neuron with vasoactive intestinal polypeptide (VIP) as neurotransmitter. These proposals were further analyzed in this study. Tetrodotoxin (TTX) and lidocaine applied on the serosal surface inhibited cholera secretion in segments of rat small intestine. Fluid absorption in control rats was not significantly changed. Hexamethonium given i.v. decreased cholera secretion in the cat. No additional inhibition of cholera secretion was observed after giving TTX close i.a. Furthermore, the intestinal secretion evoked by VIP was not influenced by hexamethonium given i.v. or TTX given close i.a. The present observations support the hypothesis of a role for nervous reflexes in cholera secretion. The results suggest that at least a major part of the proposed nervous reflex(es) in cholera have a cholinergic synapse. Furthermore, the VIP-ergic neuron is situated "distal" to the cholinergic neuron in the reflex(es) closer to the effector cells.

Topics: Animals; Cats; Cholera; Cholera Toxin; Female; Hexamethonium Compounds; Intestinal Secretions; Intestine, Small; Lidocaine; Male; Neurons; Rats; Rats, Inbred Strains; Reflex; Tetrodotoxin; Vasoactive Intestinal Peptide

The mechanisms by which bacterial enterotoxins cause secretory diarrheas have been well defined, and the definitions of such mechanisms have been important in developing a consistently successful therapeutic approach. The less common secretory diarrheas, caused by the interaction of hormones of tumor origin with the gut small intestinal mucosa have also been clearly defined, and their pathogenetic mechanisms are similar to those by which the cholera and E. coli enterotoxins cause secretory diarrhea. The mechanisms by which histamine and gastrin of tumor origin cause gastric hypersecretion are less clearly delineated; secretory diarrhea caused by both of these agents can be stopped by total gastrectomy without removal of the responsible tumor. The secretory diarrhea caused by villous adenomas of the colon, which does not appear to be related to a distally produced humoral agent, results in the same picture of hypokalemic acidosis that is characteristic of the nonbacterial secretory diarrheas originating in the small intestine and is cured by resection of the responsible tumor.

Topics: Adenoma; Antigens, Bacterial; Bacterial Toxins; Cholera; Cholera Toxin; Colonic Neoplasms; Diarrhea; Enterotoxins; Escherichia coli; Escherichia coli Infections; Escherichia coli Proteins; Fimbriae Proteins; Hormones, Ectopic; Humans; Hydrogen-Ion Concentration; Intestinal Mucosa; Neoplasms, Hormone-Dependent; Prostaglandins; Vasoactive Intestinal Peptide; Water-Electrolyte Balance; Zollinger-Ellison Syndrome

Relationships between hormonal secretions from the GI tract and gastric functional and/or pathological abnormalities could be studied according to 2 main lines : 1) gastric secretory changes could be the main symptom of hormonal secretory tumors, i.e. acid hypersecretion in the Zollinger Ellison syndrome, acid hyposecretion in pancreatic cholera and in somatostatinoma. In these cases, hormonal hypersecretion is directly responsible for the functional disturbances and the related symptoms; 2) gastric pathological conditions are sometimes accompanied by changes in hormonal secretion, but the level of interdependence is variable : high blood gastrin is directly depending upon the atrophic gastritis in pernicious anemia; this mechanism was also suggested in case of gastric carcinoma. Concerning ulcer disease, numerous problems are unsolved in respect to blood gastrin (basal and stimulated) abnormalities, as well as somatostatin and GIP secretions.

Topics: Aged; Anemia, Pernicious; Cholera; Duodenal Ulcer; Gastric Inhibitory Polypeptide; Gastric Juice; Gastrins; Gastrointestinal Hormones; Gastrointestinal Neoplasms; Humans; Pancreatic Diseases; Pancreatic Neoplasms; Somatostatin; Stomach Diseases; Vasoactive Intestinal Peptide; Zollinger-Ellison Syndrome

Topics: Adenoma, Islet Cell; Animals; APUD Cells; Biliary Tract; Cholera; Dehydration; Diarrhea; Gastric Juice; Gastrointestinal Hormones; Gastrointestinal Motility; Humans; Hypokalemia; In Vitro Techniques; Kidney Diseases; Metabolism; Neurotransmitter Agents; Pancreatic Neoplasms; Respiration; Vasoactive Intestinal Peptide