NMDA Component of the Excitatory Synaptic Transmission of Neurons Containing Serotonin or GABA in the Ventrolateral Subdivision of the Periaqueductal Gray Matter of Mouse

概要

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The midbrain periaqueductal gray( PAG) plays a crucial role in the descending pain modulating system.NMDA receptors (NMDARs) and serotonergic and GABAergic neurons have been identified in the PAGand are involved in the descending pain-modulating pathway. We characterized the NMDA component ofthe excitatory synaptic transmission within the ventrolateral subdivision of the PAG( vlPAG) using a wholecell patch clamp technique and then detected the expression of tryptophan hydroxylase (TPH), serotoninsynthesizing enzyme, and glutamate decarboxylase (GAD), GABA synthesizing enzyme to understand thevlPAG intrinsic neurotransmission. The NMDA/non-NMDA ratio and the decay time constant of theNMDA component of the non-serotonergic GABAergic neurons were significantly larger than those of nonserotonergicnon-GABAergic neurons and serotonergic GABAergic neurons. This suggests that the non-serotonergicGABAergic neurons might play an important role in the descending pain modulating systemoriginated from the PAG. The decay time constant of the NMDA component of the non-serotonergic non-GABAergic neuron was significantly greater in the mouse with partial sciatic nerve ligation compared withthe control mouse. These results suggest that the subunit composition of the NMDAR in the non-serotonergicnon-GABAergic neurons change during neuropathic pain.
2012-03-25