By in situ hybridization histochemistry, the changes of preprotachykinin (PPT) mRNA expression were examined in the neurons of adjacent thoracal dorsal root ganglion (DRG) after a strong electric stimulation to an intact dorsal cutaneous branch and the cut distal part of left T 9 thoracal spinal nerve of rat. There was a significant increase of the number of neurons expressing PPT mRNA in the ipsilateral T 8, T 9 and T 10 DRG of the animals given electric stimulation to intact spinal nerve branch 24 h after the electric stimulation. The same increase was found in the ipsilateral T 8 and T 10 DRG of the animals given electric stimulation to the distal part of spinal nerve branch. While no change was found in the DRG of the contralateral side of these animals. The present results showed that the antidromic electric stimulation strengthened the biosynthesis of PPT mRNA in adjacent DRG. These findings suggested that there was information transmission across segments between two sensory nerve endings and some bioactive substances such as SP might play important roles in the information transmission across segments of spinal cord.
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