Effect Of Metabotropic Glutamate 5 Receptor Antagonists Modulator In Rats With Neuropathic Pain

Abstract

The modulation of experimental induceded antinociception and antihyperalgesia is mediated by the metabotropic glutamate 5 (mGlu5) receptor, which is also involved in neuropathic pain. Multiple pain models benefit from the antihyperalgesic effects of systemic mGlu5 receptor antagonists (R,S)-alpha-2-methyl-4sulphonophenylglycine (MSPG). In rats with chronic neuropathic pain, the purpose of this study is to assess the effects of systemic and intrathecal (MSPG) treatment. Rats were used to create a neuropathic pain model by spinal nerve ligation (SNL) at L5–6 and CCI. Behavior tests were used, including the Von Frey and the hot water tail flick tests. On both acute and chronic pain, the effects of low, medium, and high doses of MSPG were investigated. In the Von Frey tests but not the tail flick tests, systemic and intrathecal MSPG both demonstrated dose-dependent antiallodynic effects. The antinociceptive effect in the latter test was actually diminished by high dosages of MSPG. Low dosages of MSPG reduced morphine tolerance in both tests following chronic intrathecal co-administration of MSPG. Only MSPG reduced neuropathic pain systemically, and only in the Von Frey tests—not the tail flick tests—and MSPG had no impact on morphine tolerance in either test. Using mGlu5 receptor antagonists therapeutically may have diverse outcomes in various pain models.