The role of GABA-A receptor on the dorsal root ganglion in the rats with neuropathic pain

Objective To investigate the role of GABA-A receptors in the mechanism of neuropathic pain.Methods Fifty adult female SD rats were randomly divided into five groups with 10 each.After L5 spinal nerve ligation,the rats were immediately injected with muscimol 20 μg(group A),bicuculline 0.15 μg(group B),both muscimol 20 μg and bicuculline 0.15 μg(group C),muscimol 20 μg five days later (group D),and saline 20 μl (group E).The mechanic and thermal threshold of the injured paw was measured the day before ligation and every day after the ligation until ten days later.Results L5 spinal nerve ligation induced the syndrome of neuropathic pain,such as licking injured paw and limp.The mechanic and thermal threshold of group E started to decrease on 1st day and 3rd day after pain respectively (P0.05).Then,the thresholds were stable at the 10th day (P0.05).Compared with group E,the mechanic and thermal thresholds of group A were increased and maintained a high level for 10 days.In group B,the mechanic and thermal threshold decreased on the 1st day (P0.05).Compared with group E,the mechanic and thermal thresholds of group B on the 10th day significantly decreased (P0.05).In group D,the mechanic and thermal thresholds were increased since the 6th day and followed by a transient peak on the 7th day (P0.05).Conclusion Activation of GABA-A receptors on the dorsal root ganglion can prevent the neuropathic pain,and it is just a transient effect when used afterwards.