Vagally-regulated gastric motor activity: evidence for kainate and NMDA receptor mediation.
Blockade of GABA(A) receptors in the dorsal vagal complex produces marked gastric motor excitation. This effect is abolished by a prior microinjection of a non-selective excitatory amino acid receptor antagonist. Here we present functional evidence for kainate and NMDA receptor-mediated gastric excitation in the dorsal vagal complex. Microinjections into the dorsal vagal complex were performed in alpha-chloralose-anesthetized rats using multi-barrelled glass micropipettes while recording intragastric pressure and motility. Kainic acid (30 and 100 pmol in 30 nl) and NMDA (100 and 300 pmol) produced dose-related increases in intragastric pressure and motility. The gastric responses to kainate (30 pmol) and NMDA were selectively abolished by prior microinjection 6,7-dinitroquinoxaline-2,3-dione (600 pmol, 60 nl) and DL-2-amino-5-phosphanopentanoic acid (2 nmol), respectively. Atropine (1 mg/kg, i.v.) pretreatment blocked kainate-, NMDA- and L-glutamate-induced gastric excitation. Thus, both kainate- and NMDA-receptors in the dorsal vagal complex can independently cause vagally-mediated gastric motor excitation.
Sivarao
D V
DV
Department of Pharmacology and Experimental Therapeutics, Louisiana State University Medical Center, New Orleans 70112, USA.
Krowicki
Z K
ZK
Abrahams
T P
TP
Hornby
P J
PJ
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001933:Brain Stem; D001993:Bronchodilator Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D016202:N-Methylaspartate / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology; D013270:Stomach / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D001993:Bronchodilator Agents; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; C056723:FG 9041; D016202:N-Methylaspartate; D001285:Atropine; D007608:Kainic Acid