Abstract: Objective   To study the correlation of time course and distance of brachial plexus transection on the dendritic degeneration of spinal motoneurons.    Methods   The brachial plexus of mice was transected at 3 mm or 10 mm from the intervertebral foramen, the spinal cord segments of C6~C7 was collected at 7, 14, 28 and 56 days post injury (dpi) and was subjected to perform MAP2 immunofluorescence staining, morphometric analysis, Golgi-Cox staining and Sholl analysis to assess the dendritic structure changes of spinal motoneurons. The effects of brachial plexus transection 3 mm and 10 mm from the foramina on spinal motor neuron dendrite was compared at 28 days after surgery.   Results   The brachial plexus transection resulted in that the density and integrity of dendrite in the spinal ventral horn decreased gradually with time. Golgi-Cox staining and Sholl analysis showed the longest dendrite, total dendritic length, the maximum span of dendrite and the number of third-grade dendrite branches of each spinal motoneuron decreased with time dependence. Compared with the transection at 10 mm from the intervertebral foramen, the length of dendritic degeneration in the 3 mm group was more severe.   Conclusions   The dendrite degeneration occurs and get worse in spinal motoneurons after peripheral nerve injury with time dependence, while the degree dendrite degeneration reduces with the extension of the distance between injury site and spinal cord.

Key words:  Dendrites; ,  , Motoneuron; ,  , Brachial plexus transection; ,  , Spinal cord