Modulation of serotonin 5-HT3 receptor expression in injured adult rat spinal cord motoneurons

The effects of sciatic nerve lesions on the expression of serotonin 5-HT3 r eceptor (5-HT3R) alpha subunit in motoneurons of the spinal cord was invest igated by semi-quantitative immunohistochemistry. Following sciatic nerve c rush, a significant reduction in density of staining in motoneurons was obs erved in longitudinal sections of the ventral horn at 3 and 15 days on the lesioned side when compared to the contralateral side (p < 0.01). At 30 day s after crush, after completion of sciatic nerve regeneration and reinnerva tion of peripheral targets, intensity of staining had returned to normal. C onversely, after sciatic nerve cut, a lesion that does not allow for target reinnervation, highly significant reductions were observed at 3, 15, 30 an d 45 days. These results suggest a rob for functional contacts with muscula r targets in the maintenance of 5-HT3R expression in spinal motoneurons. (C ) 1999 Elsevier Science B.V. All rights reserved.