Phosphoinositide-Linked Glutamate Receptors: Prominent Actions in Neurons and Glia
Recent studies have identified a novel glutamate receptor subtype that is coupled to activation of the phosphoinositide (PI) cycle [1–6]. To help identify the role of this receptor in mediating effects of excitatory amino acids, we have conducted electrophysiological studies in hippocampal neurons as well as biochemical studies in primary cortical cultures containing a mixture of neuronal and glial cell types. Our results add to growing evidence pointing to a prominent role of this receptor subtype in regulating both neuronal and glial activity. In particular, as described below, we have found that in hippocampal neurons stimulation of PI-linked glutamate receptors produces marked excitatory effects via blockade of K+ currents. Studies conducted in primary cortical cultures indicate that in glia this receptor subtype is coupled to stimulation of a recently identified protein kinase, referred to as microtubule-associated protein (MAP) kinase, as well as activation of several transcription factor genes.
KeywordsGlutamate Receptor Phorbol Ester Transcription Factor Gene Hippocampal Pyramidal Neuron Excitatory Amino Acid Receptor
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