Pathologic changes of spinal motoneurons function and morphology after root avulsion / 中国病理生理杂志

ABSTRACT

AIM: To investigate the pathological changes of motoneuron's function and morphology after root avulsion in order to study the neurobiology mechanism of motoneuron death. METHODS: Twenty female adult Sprague-Dawley rats, 200-300 g were used. The C 5-C 8, T 1 roots of the right brachial plexus were avulsed. All rats were killed 3 d, 5 d or 1 week after avulsion. One group of the C 5-C 8 spinal cords freeze sections (40 ?m thick) were collected for the NADPH-d histochemistry with neural red counterstained. Another group of the C 5-C 8 spinal cords freeze sections (40 ?m thick) were collected for the c-Jun immunocytochemistry stain. The paraffin sections (5 ?m thick) were collected for HE stain. The amount of NOS-positive and survival motoneurons was counted. The percentage of NOS expression and motoneuron survive were quantitatively analyzed considering the amount of contra lateral motoneurons as one hundred percent. RESULTS: The NOS expression rate was 0.74%?0.59% (3 d), 24.84%?6.73%(5 d), or 51.16%?8.67% (1 week), respectively. The survive rate was 93.00%?4.32% (3 d), 93.67%?5.27% (5 d), or 89.83%?2.65% (1 week), respectively. The motoneuron expressed c-Jun as early as 3 days after avulsion. The expression declined afterward until one week after avulsion. There was no significant change on the size of motoneuron. The nuclear membrane was still clear but some nuclei were not located in the middle of the cell body. There were some nucleoli with the chromatin condensation. CONCLUSION: The motoneuron NOS expression and cell death were increased within one week after spinal root avulsion. meanwhile, the c-jun expression was decreased. The NO/NOS may induce the motoneuron death by inhibiting the regenerating reactions of motoneuron after root avulsion injury.