Cannabinoid CB1 receptor upregulation in a rat model of chronic neuropathic pain

Although cannabinoids are known to be more effective analgesics against chr onic rather than acute pain, the mechanism underlying this phenomenon is st ill unclear. We report now that contralateral thalamic cannabinoid CB1 rece ptors are upregulated after unilateral axotomy of the tibial branch of the sciatic nerve, a rat model of chronic neuropathic pain, and hypothesize tha t cannabinoid CB1 receptor upregulation contributes to the increased analge sic efficacy of cannabinoids in chronic pain conditions. (C) 2001 Elsevier Science B.V. All rights reserved.