1. Glial glutamate transporter 1 regulates the spatial and temporal coding of glutamatergic synaptic transmission in spinal lamina II neurons.
- Author
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Weng HR, Chen JH, Pan ZZ, and Nie H
- Subjects
- Animals, Benzothiadiazines pharmacology, Dose-Response Relationship, Radiation, Drug Interactions, Electric Stimulation, Enzyme Inhibitors pharmacology, Excitatory Postsynaptic Potentials drug effects, Excitatory Postsynaptic Potentials physiology, Excitatory Postsynaptic Potentials radiation effects, Glutamic Acid pharmacology, In Vitro Techniques, Kainic Acid analogs & derivatives, Kainic Acid pharmacology, Male, Neurons drug effects, Neurons radiation effects, Oligopeptides pharmacology, Patch-Clamp Techniques methods, Rats, Rats, Sprague-Dawley, Synaptic Transmission physiology, Excitatory Amino Acid Transporter 2 physiology, Glutamic Acid metabolism, Neurons physiology, Spinal Cord cytology, Synaptic Transmission drug effects
- Abstract
Glutamatergic synaptic transmission is a dynamic process determined by the amount of glutamate released by presynaptic sites, the clearance of glutamate in the synaptic cleft, and the properties of postsynaptic glutamate receptors. Clearance of glutamate in the synaptic cleft depends on passive diffusion and active uptake by glutamate transporters. In this study, we examined the role of glial glutamate transporter 1 (GLT-1) in spinal sensory processing. Excitatory postsynaptic currents (EPSCs) of substantia gelatinosa neurons recorded from spinal slices of young adult rats were analyzed before and after GLT-1 was pharmacologically blocked by dihydrokainic acid. Inhibition of GLT-1 prolonged the EPSC duration and the EPSC decay phase. The EPSC amplitudes were increased in neurons with weak synaptic input but decreased in neurons with strong synaptic input upon inhibition of GLT-1. We suggest that presynaptic inhibition, desensitization of postsynaptic AMPA receptors, and glutamate "spillover" contributed to the kinetic change of EPSCs induced by the blockade of GLT-1. Thus, GLT-1 is a key component in maintaining the spatial and temporal coding in signal transmission at the glutamatergic synapse in substantia gelatinosa neurons.
- Published
- 2007
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