Mucosal acid challenge activates nitrergic neurons in myenteric plexus of rat stomach.
We tested the hypothesis that intrinsic neurons of the rat gastric myenteric plexus can be activated by an acid (HCl) challenge of the mucosa. Activated neurons were visualized by immunohistochemical detection of c-Fos, a marker for neuronal excitation. The neurochemical identity of the neurons activated by the HCl challenge was determined by colocalizing c-Fos with a marker for excitatory pathways, choline acetyltransferase (ChAT), and a marker for inhibitory pathways, nitric oxide synthase (NOS). Two hours after intragastric administration of HCl or saline, stomachs were removed and immunofluorescence triple labeling of myenteric neurons was carried out on whole mount preparations. Treatment with 0.35, 0.5, and 0.7 M HCl induced c-Fos in 8%, 56%, and 64%, respectively, of NOS-positive but not ChAT-positive neurons. c-Fos was also seen in glial cells of HCl-treated rats, whereas in saline-treated animals c-Fos was absent from the myenteric plexus. HCl treatment did not change the proportion of ChAT- and NOS-immunoreactive neurons in the myenteric ganglia. It is concluded that gastric acid challenge concentration-dependently stimulates a subpopulation of nitrergic, but not cholinergic, myenteric plexus neurons, which may play a role in muscle relaxation, vasodilatation, and/or secretion.
Schicho
R
R
Department of Experimental and Clinical Pharmacology, University of Graz, A-8010 Graz, Austria. rudolf.schicho@uni-graz.at
Schemann
M
M
Holzer
P
P
Lippe
I T
IT
D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D051959:ELAV Proteins; D005260:Female; D005753:Gastric Mucosa / Q000187:drug effects*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006851:Hydrochloric Acid / Q000494:pharmacology*; D009197:Myenteric Plexus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride / Q000494:pharmacology; D013270:Stomach / Q000294:innervation*
D051959:ELAV Proteins; D005904:Glial Fibrillary Acidic Protein; D016760:Proto-Oncogene Proteins c-fos; D016601:RNA-Binding Proteins; D012965:Sodium Chloride; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D002795:Choline O-Acetyltransferase; D006851:Hydrochloric Acid