The Journal of Neuroscience, May 1, 2000, 20(9):3200-3205
Agonist- and Reflex-Evoked Internalization of Metabotropic
Glutamate Receptor 5 in Enteric Neurons
Min-tsai
Liu and
Annette L.
Kirchgessner
Department of Physiology and Pharmacology, State University of New
York Health Science Center at Brooklyn, Brooklyn, New York, 11203
We demonstrate that metabotropic glutamate receptor 5 (mGluR5) is
present in the guinea pig ileum. A punctate ring-like distribution of
immunoreactivity is found on the soma of a subset of neurons, consistent with an association of mGluR5 with the plasma membrane. mGluR5-containing cells in the submucosal plexus are predominantly noncholinergic and contain vasoactive intestinal peptide, a marker of
secretomotor neurons. Using immunocytochemistry in conjunction with
confocal microscopy, we show that the mGluR5 undergoes agonist- and
reflex-evoked internalization that is inhibited by the group I
antagonist 1-aminoindan-1,5-dicarboxylic acid. In addition, group I
mGluR antagonists reduce the distension-induced phosphorylation of
cAMP-responsive element-binding protein in enteric neurons and
attenuate both glutamate- and group I agonist-induced depolarizing responses and slow synaptic events in submucosal neurons. These findings support the idea that mGluRs play a role in enteric reflexes and suggest that internalization might be a major mechanism for regulation of mGluR activity.
Key words:
glutamate; electrophysiology; DHPG; CHPG; AIDA; S-4CPG; MPEP; pCREB
Copyright © 2000 Society for Neuroscience 0270-6474/00/2093200-06$05.00/0