P2X receptor-mediated excitatory synaptic currents in somatosensory cortex

Area of Science:

• Neuroscience
• Cellular Neuroscience
• Synaptic Physiology

Background:

• Pyramidal neurons in layer V of the somatosensory cortex play a crucial role in sensory processing.
• Fast excitatory postsynaptic currents (EPSCs) are fundamental to neuronal communication.
• The role of P2X purinergic receptors in neocortical synaptic transmission is not fully elucidated.

Purpose of the Study:

• To investigate the involvement of P2X receptors in mediating fast synaptic currents in rat somatosensory cortex.
• To characterize the properties of non-glutamatergic EPSCs in layer V pyramidal neurons.

Main Methods:

• Acute isolation of brain slices from young rats (17-22 days old).
• Electrophysiological recordings of excitatory postsynaptic currents (EPSCs) in layer V pyramidal neurons.
• Pharmacological manipulation using glutamate receptor antagonists (NBQX, D-AP5), nicotinic receptor blockers (hexamethonium), serotonin receptor blockers (Y25130), and P2X receptor antagonists (NF023, NF279, PPADS).
• Application of ATP and its analogs to evoke currents.

Main Results:

• A residual EPSC (rEPSC), distinct from glutamatergic transmission, was recorded in 85% of tested neurons after blocking glutamate receptors.
• The rEPSC was insensitive to nicotinic and serotonin receptor blockers.
• The rEPSC was reversibly inhibited by P2X receptor antagonists.
• Application of ATP and its analogs evoked inward currents in 75% of layer V pyramidal neurons.

Conclusions:

• P2X receptors mediate fast synaptic transmission in the neocortex.
• Multiple subtypes of P2X purinoreceptors are involved in synaptic transmission in the somatosensory cortex.
• These findings highlight the significant role of purinergic signaling in cortical circuitry.