Modulation of Formalin-Evoked Hyperalgesia by Intrathecal N-Type Ca Channel and Protein Kinase C Inhibitor in the Rat

1. -CgTx attenuated formalin-evoked biphasic flinches, while PKC inhibitor (STU) attenuated phase 2 and was reversed by PDBu.2. -CgTx and STU suppressed the increase in CSF-glutamate after formalin injection.3. Morphine completely suppressed both increased flinching and CSF glutamate release.4. Thus, -CgTx (N-type Ca channels) may regulate neurotransmitter release evoked by C fiber activation and the formalin-evoked hyperalgesia may possibly be provoked as a result of PKC activation elicited by both presynaptic neurotransmitter release and activation of NMDA receptors in the spinal neurons.