N-methyl-D-aspartate-dependent long-term potentiation of excitatory transmission in trigeminal subnucleus oralis

Abstract

This study for the first time demonstrates early developmental changes of passive/active membrane properties, and long-term potentiation (LTP) of excitatory synaptic transmission at spinal trigeminal subnucleus caudalis (Vc)-to-oralis (Vo) synapses. During postnatal development, the probability of Vo neurons with monosynaptic excitatory postsynaptic currents (EPSCs) upon Vc stimulation significantly increased, whereas the input resistances of Vo neurons and the latencies of monosynaptic EPSCs significantly decreased. Application of a 'pairing' protocol that comprises 2 Hz-conditioning stimulation of Vc with postsynaptic depolarization of Vo neuron to +30 mV generated LTP of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor-mediated monosynaptic EPSC amplitude in more than 70% of Vo neurons. The induction of LTP required the activation of N-methyl-D-aspartate receptor, but its magnitudes had correlation neither with postnatal ages nor with baseline EPSC amplitudes.

Hyperalgesia by synaptic long-term potentiation (LTP): an update

“…It is thus not surprising that LTP is not only expressed at the first synaptic relays in nociceptive pathways [14,15,18 •• ]. LTP has also been observed at synapses of glutamatergic [28] and GABAergic [50] interneurons in superficial spinal dorsal horn and at excitatory synapses between neurons in the spinal trigeminal subnucleus caudalis and -oralis [58]. Furthermore, LTP can be elicited at synapses in putatively nociceptive relays in the anterior cingulate cortex [59–61].…”

Signal Transduction Mechanisms Underlying Group I Mglur-Mediated Increase in Frequency and Amplitude of Spontaneous EPSCs in the Spinal Trigeminal Subnucleus Oralis of the Rat

“…Blind whole-cell recordings with patch pipettes (borosilicate glass, TW150F; WPI, Sarasota, FL, USA) were made from Vo neurons. When viewed under a microscope (BX51WI, Olympus, Tokyo, Japan) with transmitted illumination (40×), the caudal border of the Vo area was distinguishable with the Vi area although it was difficult to discern with the rostral border of the Vo area [ 51 , 52 ]. Under visual guidance, the tip of the patch pipette was positioned in the Vo area above the caudal border with the Vi.…”