title: H. pylori acutely inhibits gastric secretion by activating CGRP sensory neurons coupled to stimulation of somatostatin and inhibition of histamine secretion.
abstract: Acute Helicobacter pylori infection produces hypochlorhydria. The decrease in acid facilitates survival of the bacterium and its colonization of the stomach. The present study was designed to identify the pathways in oxyntic mucosa by which acute H. pylori infection inhibits acid secretion. In rat fundic sheets in an Ussing chamber, perfusion of the luminal surface with H. pylori in spent broth (10(3)-10(8) cfu/ml) or spent broth alone (1:10(5) to 1:10(0) final dilution) caused a concentration-dependent increase in somatostatin (SST; maximal: 200 ± 20 and 194 ± 9% above basal; P < 0.001) and decrease in histamine secretion (maximal: 45 ± 5 and 48 ± 2% below basal; P < 0.001); the latter was abolished by SST antibody, implying that changes in histamine secretion reflected changes in SST secretion. Both responses were abolished by the axonal blocker tetrodotoxin (TTX), the sensory neurotoxin capsaicin, or the CGRP antagonist CGRP8-37, implying that the reciprocal changes in SST and histamine secretion were due to release of CGRP from sensory neurons. In isolated rabbit oxyntic glands, H. pylori inhibited basal and histamine-stimulated acid secretion in a concentration-dependent manner; the responses were not affected by TTX or SST antibody, implying that H. pylori can directly inhibit parietal cell function. In conclusion, acute administration of H. pylori is capable of inhibiting acid secretion directly as well as indirectly by activating intramural CGRP sensory neurons coupled to stimulation of SST and inhibition of histamine secretion. Activation of neural pathways provides one explanation as to how initial patchy colonization of the superficial gastric mucosa by H. pylori can acutely inhibit acid secretion.
authors: Department of Medicine, Virginia Commonwealth University's Medical College of Virginia, Richmond, VA, USA.
authors: Muhammad
authors: M
authors: Zaki
authors: Philip E
authors: PE
authors: Coudron
authors: Robert W
authors: RW
authors: McCuen
authors: Leslie
authors: L
authors: Harrington
authors: Shijian
authors: S
authors: Chu
authors: Mitchell L
authors: ML
authors: Schubert
mesh_terms: D000126:Achlorhydria / Q000378:metabolism / Q000382:microbiology*; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D004195:Disease Models, Animal; D005744:Gastric Acid / Q000378:metabolism; D005748:Gastric Fundus / Q000294:innervation / Q000378:metabolism / Q000382:microbiology; D005753:Gastric Mucosa / Q000294:innervation / Q000378:metabolism / Q000382:microbiology; D006367:HeLa Cells; D016481:Helicobacter Infections / Q000378:metabolism* / Q000382:microbiology; D016480:Helicobacter pylori / Q000378:metabolism*; D006632:Histamine / Q000378:metabolism; D006801:Humans; D010295:Parietal Cells, Gastric / Q000378:metabolism / Q000382:microbiology; D010446:Peptide Fragments / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013004:Somatostatin / Q000378:metabolism* / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D010446:Peptide Fragments; D026941:Sodium Channel Blockers; C058636:calcitonin gene-related peptide (8-37); D013779:Tetrodotoxin; D013004:Somatostatin; D006632:Histamine; D015740:Calcitonin Gene-Related Peptide