Nakatsuka T, Takeda D, Gu JG (2001) α,β-methylene ATP sensitive P2X receptor mediated enhancement of glutamate release from the central terminals of Aδ primary afferents onto lamina V neurons in rat spinal cord. Neuroscience 2001 Abstracts 158.16. Society for Neuroscience, San Diego, CA.
Summary: We examined the role of αβmATP-sensitive P2X receptors in modulating glutamate release from sensory synapses of the spinal cord by using whole-cell patch-clamp recordings from dorsal horn neurons in lamina V region. The majority of lamina V neurons synapsed with terminals expressing αβmATP-sensitive P2X receptors. Application of P2X receptor agonist 100 μM αβmATP resulted in a large increase in mEPSC frequency. The increases in mEPSC frequency by αβmATP were completely abolished by the P2X receptor antagonist 10 μM PPADS, but were not blocked by Ca2+ channel blocker 30 μM La3+. αβmATP remained to be effective in increasing mEPSC frequency after the removal of superficial dorsal horn (lamina I-III) or after the injection of IB4-saporin into sciatic nerve to remove P2X3 expressing afferent terminals. Furthermore, we found that αβmATP-sensitive synapses of lamina V neurons were associated with central terminals derived from Aδ primary afferents. The EPSCs evoked by dorsal root stimulation at Aδ-fiber intensity were potentiated by 1 μM αβmATP as well as by the ecto-ATPase inhibitor 10 μM ARL67156, and depressed in the presence of 10 μM PPADS and 5 μM suramin. These results suggest that αβmATP-sensitive P2X receptors play a significant role in modulating excitatory synaptic transmission in the spinal cord.
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