Glutamate modulates neurotransmission in the submucosal plexus of guinea-pig small intestine.
Effects of glutamate on synaptic transmission in the submucosal plexus of guinea-pig small intestine were studied with intracellular electrophysiological recording methods. Glutamate suppressed stimulus-evoked slow excitatory postsynaptic potentials (EPSPs) and increased the amplitude of slow inhibitory postsynaptic potentials (IPSPs) in submucosal neurons. The actions of glutamate were mimicked by the group I metabotropic glutamate receptor (mGluRs) agonist DHPG, but not by the group II agonist S-4C3HPG, the group III agonist L-AP4, or selective agonists for ionotropic glutamate receptors (iGluRs). Glutamate actions were suppressed by the selective group I mGluRs antagonist S-4CPG, but not by group II and III mGluRs antagonist CPPG or iGluRs antagonists. Glutamate suppressed substance P- and 5-HT-evoked slow EPSP-like responses and potentiated norepinephrine-induced slow IPSP-like responses. The results suggest that group I mGluRs mediate glutamate-induced suppression of slow EPSPs and potentiation of slow IPSPs in S-type uniaxonal submucosal neurons.
Ren
J
J
Department of Physiology, College of Medicine and Public Health, The Ohio State University, Columbus 43210-1218, USA.
Hu
H Z
HZ
Liu
S
S
Xia
Y
Y
Wood
J D
JD
D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D018698:Glutamic Acid / Q000502:physiology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000294:innervation*; D007421:Intestine, Small / Q000294:innervation*; D008297:Male; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors; D009435:Synaptic Transmission / Q000502:physiology*
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018094:Receptors, Metabotropic Glutamate; D018698:Glutamic Acid