Agents that act by different mechanisms modulate the activity of protein kinase CβII isozyme in the rat spinal cord during peripheral inflammation

Abstract

Hyperalgesia following unilateral complete Freund’s adjuvant-induced inflammation was characterized by paw withdrawal latency to thermal stimulus. Paw withdrawal latencies were significantly shorter on the complete Freund’s adjuvant-treated paw than on the contralateral paw of the complete Freund’s adjuvant- and the sham-treated rats. Total cytosolic protein kinase C activity in the lumbar enlargement was unchanged on the sides of the spinal cord ipsi- and contra-lateral to the inflamed paw. Membrane-associated activities of protein kinase Cα, protein kinase CβI and protein kinase Cγ did not change significantly on the sides of the cord ipsi- and contra-lateral to the inflammation. However, membrane-associated activity of protein kinase CβII was increased in the cord section ipsilateral to the inflammation, suggesting that increased translocation/activation of protein kinase CβII is related to thermal hyperalgesia. Dextrorphan (an N-methyl- d-aspartate receptor antagonist), L-703,606 (an NK-1 receptor antagonist) and an antisense oligodeoxynucleotide for a selective knockdown of protein kinase Cβ, reduced complete Freund’s adjuvant-induced hyperalgesia, and reversed significant changes in the membrane activity of protein kinase CβII on the spinal cord section ipsilateral to the inflamed paw. Dextrorphan and protein kinase Cβ antisense oligodeoxynucleotide were effective in reversing complete Freund’s adjuvant-induced increase in the activity of protein kinase CβII ipsilateral to the inflammation at all the doses tested, but L-703,606 was effective only at the highest dose. Furthermore, in the presence of inflammatory stimulus, dextrorphan and L-703,606 did not alter the activities of membrane-associated protein kinase Cα, protein kinase CβI, and protein kinase Cγ in the section of the spinal cord ipsi- and contra-lateral to the inflammation. Protein kinase Cβ antisense oligodeoxynucleotide had no significant effect on the membrane-associated activities of protein kinase Cα and protein kinase Cγ, but decreased the activities of both protein kinase CβI and protein kinase CβII and the expression of protein kinase Cβ isozyme in the spinal cord. The data provide evidence that a common molecular event that converges to initiate and maintain hyperalgesia may include the translocation and activation of protein kinase CβII in the spinal dorsal horn.