HMOX1 and diabetic neuropathy: In vivo studies have demonstrated reduced Nrf2 and/or HO-1 levels in the spinal cord of animals with neuropathic pain [12,21] or diabetic neuropathy [22,23,24,25], in which the levels were restored by treatment with several pharmacological modulators of Nrf2 and HO-1 [12,26,27,28].