Somatosensory Systems, PainNMDA receptors are important for both mechanical and thermal allodynia from peripheral nerve injury in ratsKim, Yang In1; Na, Heung Sik1,2,3; Yoon, Young Wook1; Han, Hee Chul1; Ko, Kyeong Hee1; Hong, Seung Kil1,2Author Information 1Neuroscience Research Institute and Department of Physiology, Korea University College of Medicine, 126-1 Anam-dong 5 Ga, Sungbuk-gu, Seoul, Korea 136-705 2Graduate School of Biotechnology, Korea University 3Corresponding Author and Address: Heung Sik Na, Neuroscience Research Institute and Department of Physiology, Korea University College of Medicine, 126-1 Anam-dong 5 Ga, Sungbuk-gu, Seoul, Korea 136-705 ACKNOWLEDGEMENTS: This study was supported by Research Fund for Basic Medicine, Ministry of Education (95-042) and by The Research Institute of Life Science, Korea University. Received 18 March 1997; accepted 12 April 1997 NeuroReport: July 7th, 1997 - Volume 8 - Issue 9 - p 2149-2153 Buy Abstract PREVIOUS studies showed that heat-hyperalgesia and mechanical allodynia produced by chronic constrictive injury of the sciatic nerve were differentially sensitive to the NMDA receptor antagonist dextrorphan and to morphine and other opioid receptor agonists. These results support the hypothesis that different kinds of neuropathic pain symptoms are caused by different pathological mechanisms. In the present study we determined whether mechanical and thermal allodynia produced by unilateral transection of the ‘superior’ caudal trunk which innervates the tail in rats were differentially sensitive to the non-competitive NMDA receptor antagonist MK-801. Injection of MK-801 (0.3 mg/kg, i.p.) prior to nerve injury delayed the emergence of both types of allodynia; the antagonist-treated rats exhibited neither mechanical nor thermal allodynia at least for 4 days after the injury, whereas untreated control rats exhibited clear signs of allodynia from the first day after the injury. MK-801 injection on post-injury day 14, when the allodynia was near peak severity, suppressed temporarily both the mechanical and thermal allodynia. These results suggest that the mechanical and thermal allodynia from partial denervation of the tail are both dependent on NMDA receptors in their induction and maintenance. Thus, our results do not support the notion that different pathological mechanisms underlie different modalities of neuropathic pain from partial peripheral nerve injury. © Lippincott-Raven Publishers.