SHORT-TERM PLASTICITY IN TURTLE DORSAL HORN NEURONS MEDIATED BY L-TYPE CA2+ CHANNELS

Windup-the gradual increase of the response-of dorsal horn neurons to repeated activation of primary afferents is an elementary form of shor t-term plasticity that may mediate central sensitization to pain. In d eep dorsal horn neurons of the turtle spinal cord in vitro we report w indup of the response to repeated depolarizing current pulses as well as to repeated stimulation of the ipsilateral dorsal root. We found bo th forms of windup to be mediated by a depolarizing potential produced by increasing activation of postsynaptic L-type Ca2+ channels. These results suggest a central role for intrinsic postsynaptic properties i n nociceptive plasticity and for L-type Ca2+ channels as a promising t arget for therapeutic intervention.