GADD45G and Intervertebral disk degeneration: In the present study, our findings of elevated Gadd45g expression in the amygdala of SNL rats agree with increased Gadd45β in the spinal dorsal horn after SNL surgery in rats [56], in the anterior cingulate cortex after sciatic nerve injury in rats [57], and increased Gadd45g protein expression in human nucleus pulposus cells isolated from advanced stages of intervertebral disc degeneration (a form of NP) [50].