Phosphorylation of c-Jun N-terminal kinase isoforms and their different roles in spinal cord dorsal horn and primary somatosensory cortex.

The present study was undertaken to investigate whether isoforms of c-Jun N-terminal kinase (JNK 46 kDa and 54 kDa), one component of the mitogen-activated protein kinase (MAPK) family, might show region-related differential activation patterns in both naïve and pain-experiencing rats. In naïve rats, no significant difference was observed in total expression level of the two JNK isoforms between spinal cord and primary somatosensory cortex (S1 area). However, phosphorylated JNK 46 kDa was normally expressed in the S1 area, but not in the spinal cord, while neither of the two structures contained phosphorylated JNK 54 kDa.

Region- or state-related differences in expression and activation of extracellular signal-regulated kinases (ERKs) in naïve and pain-experiencing rats.

Background: Extracellular signal-regulated kinase (ERK), one member of the mitogen-activated protein kinase (MAPK) family, has been suggested to regulate a diverse array of cellular functions, including cell growth, differentiation, survival, as well as neuronal plasticity. Recent evidence indicates a role for ERKs in nociceptive processing in both dorsal root ganglion and spinal cord. However, little literature has been reported to examine the differential distribution and activation of ERK isoforms, ERK1 and ERK2, at different levels of pain-related pathways under both normal and pain states.