Inhibition of spinal protein kinase C reduces nerve injury-induced tactile allodynia in neuropathic rats.

We investigated the effects of inhibiting spinal protein kinases including PKC, PKA and PKG on tactile allodynia in rats with a unilateral tight ligation on L5/L6 spinal nerves (Chung model). The intrathecal (IT) delivery of GF109203X, a PKC inhibitor, produced a potent and long lasting anti-allodynic effect. The effect was dose-dependent and stereospecific. Bisindolymaleimide V, an inactive homologue of GF, had no effect. Additionally, two other PKC inhibitors, PKC19-31 and chelerythrine, displayed significant anti-allodynic action. Spinal PKA, but not PKG, is likely involved in Chung tactile allodynia, since H89 (a PKA inhibitor) showed anti-allodynic activity, while KT5823 (a PKG inhibitor) had only a minor effect. These data emphasize that spinal PKC plays an important role in nerve injury-induced tactile allodynia. Other protein kinases such as PKA may also contribute to this phenomenon.