A Novel Nociceptor Signaling Pathway Revealed in Protein Kinase C ε Mutant Mice

AbstractThere is great interest in discovering new targets for pain therapy since current methods of analgesia are often only partially successful. Although protein kinase C (PKC) enhances nociceptor function, it is not known which PKC isozymes contribute. Here, we show that epinephrine-induced mechanical and thermal hyperalgesia and acetic acid–associated hyperalgesia are markedly attenuated in PKCε mutant mice, but baseline nociceptive thresholds are normal. Moreover, epinephrine-, carrageenan-, and nerve growth factor– (NGF-) induced hyperalgesia in normal rats, and epinephrine-induced enhancement of tetrodotoxin-resistant Na+ current (TTX-R INa) in cultured rat dorsal root ganglion (DRG) neurons, are inhibited by a PKCε-selective inhibitor peptide. Our findings indicate that PKCε regulates nociceptor function and suggest that PKCε inhibitors could prove useful in the treatment of pain