DiscussionIntrathecal administration of GABA receptor antagonists has been shown to cause hyperalgesia and allodynia. Constitutive, increased endogenous GABA activity in the spinal cord attenuates pain resulting from noxious and innocuous mechanical and thermal stimuli. Different GABA receptors play different roles in thermal and mechanical pain relief in different animal pain models. To date, there is no study that has examined the involvement of GABA A and GABA B in the sensory dimension of neuropathic pain resulting from spinal cord compression. The present study tests the hypothesis that GABA A or GABA B receptors contribute to the allodynia and hyperalgesia observed after spinal cord injury. The results showed that the effect of GABA A and GABA B receptors on mechanical hyperalgesia is similar but that these receptors have different effects on thermal hyperalgesia. Although the use of baclofen as a GABA B receptor agonist did not affect thermal pain, thermal hyperalgesia resulting from spinal cord injury was greatly attenuated by different doses of the GABA A agonist muscimol . Both baclofen and muscimol are able to reduce mechanical and cold allodynia observed after spinal cord injury, but the effect of baclofen is dose dependent, with no effect at the higher doses used in this study. While almost all doses of muscimol were used in this study, they reduced the amount of cold and mechanical allodynia. The other result obtained in this study is the short-term effect of the GABA agonist. The antinociceptive effect of baclofen and muscimol appears to be maximum 15 minutes after injection and gradually decrease with time and their analgesic effect disappears 3 hours after injection. Currently, pharmacological mechanisms affect neurons.... middle of the article..... .tive to intrathecal administration of morphine than to tactile allodynia. Therefore, consideration of both modalities is important when considering the spinal pharmacology of the nerve-injured condition. Our results provide the first demonstration that selective GABAA, but not GABA B, receptor agonists reverse thermal hyperalgesia produced by spinal cord injury. In parallel, we demonstrate that in spinal cord injuries similar to peripheral nerve injuries, GABAA and GABAB receptor agonists reduce cold and tactile allodynia and mechanical hyperalgesia. Additionally, our studies used a sensitive and reproducible test of motor function to compare the antiallodynic, antihyperalgesic, and motor effects of GABA receptor agonists. Data suggest that GABAA agonists may be effective in the treatment of neuropathic pain accompanied by thermal hyperalgesia without sensory or motor side effects..