Synaptic activation of metabotropic glutamate receptors regulates dendritic outputs of thalamic interneurons.
Information gating through the thalamus is dependent on the output of thalamic relay neurons. These relay neurons receive convergent innervation from a number of sources, including GABA-containing interneurons that provide feed-forward inhibition. These interneurons are unique in that they have two distinct outputs: axonal and dendritic. In addition to conventional axonal outputs, these interneurons have presynaptic dendrites that may provide localized inhibitory influences. Our study indicates that synaptic activation of metabotropic glutamate receptors (mGluRs) increases inhibitory activity in relay neurons by increasing output of presynaptic dendrites of interneurons. Optic tract stimulation increases inhibitory activity in thalamic relay neurons in a frequency- and intensity-dependent manner and is attenuated by mGluR antagonists. Our data suggest that synaptic activation of mGluRs selectively alters dendritic output but not axonal output of thalamic interneurons. This mechanism could serve an important role in focal, feed-forward information processing in addition to dynamic information processing in thalamocortical circuits.
Govindaiah
Department of Molecular and Integrative Physiology, University of Illinois, Urbana, IL 61801, USA.
Cox
Charles L
CL
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000344:Afferent Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D003712:Dendrites / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005829:Geniculate Bodies / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007395:Interneurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013788:Thalamus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018691:Excitatory Amino Acid Antagonists; D018094:Receptors, Metabotropic Glutamate; D005680:gamma-Aminobutyric Acid