Miniature postsynaptic currents recorded from identified rat spinal dorsal horn projection neurons in thin-slice preparations.

Whole-cell voltage-clamp recordings were made from spinothalamic and spinomesencephalic tract neurons in thin-slice preparations of rat spinal cord. In the presence of tetrodotoxin, spontaneous inward and outward postsynaptic currents were observed near the resting membrane potential. These currents were divided into miniature excitatory postsynaptic currents (mEPSCs) mediated by glutamate, and miniature inhibitory postsynaptic currents (mIPSCs) mediated by glycine or gamma-aminobutyric acid (GABA). Glutamatergic mEPSCs had two components mediated by NMDA and non-NMDA receptors. Analyzing these miniature synaptic currents, valuable information concerning the pre- and postsynaptic mechanisms underlying modulation of synaptic transmission in the spinal dorsal horn could be obtained.