Apoptosis of neuron in cerebral motor cortex after spinal cord injury in rat

English Keywords:Spinal cord injury  Neuron  Apoptosis  Motor cortex  Rat

English Abstract:

  【Abstract】 Objectives: To investigate the apoptosis of neuron in cerebral motor cortex after spinal cord injury(SCI) in rat. Methods: Seventy-two SD rats were divided into 3 groups randomly as follows: control group(intact), sham-operation group(laminectomy only) and SCI group(laminectomy and spinal cord transection injury at T10). There were 24 rats in each group. Six rats in each group were sacrificed respectively on the 1st day, 3rd day, 7th day and 14th day after operation. TUNEL was applied to detect apoptosis of neurons in motor cortex after spinal cord injury. Expression of iNOS of neurons in the same area was also investigated. Then the relationship of apoptosis and expression of iNOS of neurons in motor cortex was analyzed. Results： Apoptosis index（AI） of SCI group was (10.11±4.02)%, (56.53±8.63)%, (35.03±11.66)%, (3.78±1.03)% on the 1st day, 3rd day, 7th day and 14th day after SCI respectively, which was higher than that of control group and sham-operation group(P<0.05). Compared with the other time points(the 1st day,7th day and 14th day), AI on the 3rd day was higher(P<0.01) in SCI group. Percentage of iNOS positive neurons on the 1st day, 3rd day, 7th day and 14th day in SCI group was (17.92±2.75)%, (60.65±8.78)%, (34.35±7.74)%, (6.12±1.99)% respectively. On the 1st day, 3rd day, 7th day, percentage of iNOS positive neurons in SCI group was higher than that of control group and sham-operation group(P<0.05) respectively. But there was no significant difference among the 3 groups on the 14th day. Compared with the other time point, percentage of iNOS positive neurons on the 3rd day was higher in SCI group(P<0.01). AI showed positive correlation with percentage of iNOS positive neurons in SCI group(r=0.89, P<0.01). Conclusions: Apoptosis of neuron in cerebral motor cortex increases after SCI in rat. After SCI, which may be related with the increased expression of iNOS.