title: Inhibitory effect of somatostatin on Helicobacter pylori proliferation in vitro.
abstract: OBJECTIVE
  Somatostatin regulates gastric function and cell proliferation. We investigated whether exogenous somatostatin modulates Helicobacter pylori proliferation in vitro.
  
  
  METHODS
  Bacteria were cultured in 5 mL Brucella broth. Bacterial numbers of H. pylori (ATCC 43504) and Escherichia coli were calculated 48 and 5 hours after incubation, respectively, by counting the colonies on the blood agar. Chemicals were dissolved in absolute methanol and added to the broth at a final methanol concentration of 1%. Intrabacterial guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP) levels were measured by radioimmunoassay.
  
  
  RESULTS
  Somatostatin significantly suppressed H. pylori proliferation at levels at or above 10(-11) mol/L. A similar antiproliferative effect was observed with 8-bromo-cGMP. At concentrations at or above 10(-8) mol/L, dibutyryl cAMP slightly but significantly stimulated bacterial proliferation. Gastrin had no effect. Somatostatin antibody immunoglobulin G fraction blocked the antiproliferative effect of somatostatin on ATCC 43504. Scatchard plot showed that ATCC 43504 has one class of binding site with relatively high affinity (Kd, 0.31 nmol/L). Somatostatin at 10(-11) mol/L increased cGMP and cAMP in H. pylori 11-fold and 6-fold, respectively. In contrast, somatostatin neither bound E. coli nor affected its proliferation.
  
  
  CONCLUSIONS
  Somatostatin, at a similar level in human gastric juice (approximately 10(-11) mol/L), suppresses H. pylori proliferation mediated in part by a cGMP-dependent pathway in vitro, indicating a possible inhibitory effect of somatostatin in the gastric lumen on H. pylori proliferation in humans.
authors.affiliation: Fourth Department of Internal Medicine, Aichi Medical University, Aichi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yamashita
authors.forename: H
authors.initials: H
authors.lastname: Kaneko
authors.forename: S
authors.initials: S
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Konagaya
authors.forename: K
authors.initials: K
authors.lastname: Kusugami
authors.forename: T
authors.initials: T
authors.lastname: Mitsuma
mesh_terms: D000906:Antibodies / Q000276:immunology; D001426:Bacterial Proteins / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016480:Helicobacter pylori / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D013004:Somatostatin / Q000276:immunology / Q000494:pharmacology*
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D013004:Somatostatin; D000242:Cyclic AMP; D006152:Cyclic GMP