Pathophysiology of spinal cord injury has classically bad prognosis in primary and secondary processes. This process causes inflammation, deformity and cell loss. It has been shown that Melissa officinalis is a useful herbal plant in the prevention of various neurological diseases. The present study evaluated the effects of three doses of Melissa officinalis on spinal cord injury. Thirty five adult male wistar rats were used in this study. The weight-drop contusion method was employed to induce spinal cord injury in rats. Three doses of Melissa officinalis (50, 100 and 150 mg/kg) were intraperitoneally injected once a day for 14 days in all treatment groups and all injections started one day after injury. After neurological and electrophysiological evaluations, rats were sacrificed for histological and immunohistochemistry assessments. Our results showed motor function was improved in groups received 100 and 150 mg/kg of Melissa officinalis and sensory recovery was better in 150 mg/kg of Melissa officinalis treated group compared to spinal cord injury group (p<0. 01, p<0. 001 respectively). Mean cavity area in 100 and 150 mg/kg (p<0. 01) significantly decreased compared to spinal cord injury group. In addition, three doses of Melissa officinalis considerably prevented loss of lower motor neurons in the ventral horn of spinal cord (p<0. 05, p<0. 01). Also, Melissa officinalis (100 and 150 mg/kg) prevented of astrogliosis effectively (p<0. 01). Furthermore, the findings showed a significant augmentation of EMG recruitment index in groups which treated by 100 mg/ kg (P <0. 01) and 150 mg/ kg (P <0. 001) of Melissa officialis. The results showed that Melissa Officinalis could be considered as a neuroprotective agent in spinal cord injury.

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