[Post-traumatic survival in different subpopulations of sensory neurons]

An expression of high molecular component of neurofilament triplet NF200 (marker of neurons forming A-fibers) and binding of isolectin B4 (IB4) was examined immunohistochemically in LIV-LV dorsal root ganglia (DRG) neurons after ligation or transection of the sciatic nerve in rat. NF200 immunoreactivity was detected in 15% of all neurons in DRG of intact rats. Ligation of sciatic nerve caused a two-fold decrease in number of NF200-positive neurons by 90th day after nerve injury, however in animals treated with peripheral nerve regeneration stimulator xymedon the number of surviving NF200-positive neurons was increased by 50.7% as compared with control group (nerve ligation without treatment). In DRG of intact rats 23.6% of neurons showed IB4 binding. Of the DRG neurons 2.6% were labeled by IB4 at 30th day after ligation of the nerve. At 90th day after ligation no IB4-positive neurons were revealed in DRG of untreated rats, while xymedon treatment was shown to result in more than 8-fold increase in the number of surviving IB4-positive neurons. IB4-positive neurons have greater probability of entering the posttraumatic apoptosis. After nerve ligation the survival of NF200- and IB4-positive neurons was less than that one following nerve transection, suggesting that axon lengthening could be a the factor supporting neuronal survival. Pyrimidine derivative xymedon promoted the survival of neurons in both subpopulations with predominant effect on IB4-positive neurons.