Dendritic glutamate release produces autocrine activation of mGluR1 in cerebellar Purkinje cells.
In recent years, it has become clear that, in addition to conventional anterograde transmission, signaling in neural circuits can occur in a retrograde manner. This suggests the additional possibility that postsynaptic release of neurotransmitter might be able to act in an autocrine fashion. Here, we show that brief depolarization of a cerebellar Purkinje cell triggers a slow inward current. This depolarization-induced slow current (DISC) is attenuated by antagonists of mGluR1 or TRP channels. DISC is eliminated by a mixture of voltage-sensitive Ca2+ channel blockers and is mimicked by a brief climbing fiber burst. DISC is attenuated by an inhibitor of vesicular glutamate transporters or of vesicular fusion. These data suggest that Ca2+-dependent postsynaptic fusion of glutamate-loaded vesicles evokes a slow inward current produced by activation of postsynaptic mGluR1, thereby constituting a useful form of feedback regulation.
Shin
Jung Hoon
JH
Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, 916 Hunterian Building, Baltimore, MD 21205, USA.
Kim
Yu Shin
YS
Linden
David J
DJ
D000818:Animals; D019898:Autocrine Communication; D002118:Calcium / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism*; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials; D018698:Glutamic Acid / Q000378:metabolism*; D018613:Microscopy, Confocal; D008954:Models, Biological; D011689:Purkinje Cells / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction
D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D018698:Glutamic Acid; D002118:Calcium