[Investigation on the mechanism of discogenic groin pain]

To investigate the mechanism of discogenic groin pain.

Twenty-one adult wistar rats were divided into experimental group (paravertebral sympathetic trunks were reserved), control group (paravertebral sympathetic trunks were resected) and self-control group (right paravertebral sympathetic trunks were resected, the left ones were reserved) randomly. Each group has 7 rats. Horseradish peroxidase (HRP) were injected into the L5-L6 intervertebral discs from right postero-lateral side. Bilateral L1, L2 spinal ganglia were sectioned after 48 hours to observe the HRP labeled cells and the effect of resection of paravertebral sympathetic trunks. Another 7 adult wistar rats were used. The same steps of injection, removal and section as in experimental group were taken. Combining method of HRP retrograde tracer with immunocytochemistry stained the sections to determine the nature of HRP labeled cells.

HRP labeled cells were found in bilateral L1, L2 spinal ganglia in each group. The comparison results of labeled cells numbers between groups (experimental group from 22.5 +/- 7.1 to 29.3 +/- 9.7, control group from 12.9 +/- 5.1 to 13.3 +/- 4.9, P < 0.01) and of self-control group (left 24.8 +/- 6.7, 30.6 +/- 8.4, right 15.8 +/- 4.4, 14.5 +/- 4.1, P < 0.01) show that the numbers of HRP labeled cells were significantly less than that after resection of paravertebral sympathetic trunks. HRP and SP double-labeled cells can be recognized in bilateral L1, L2 spinal ganglia in immunocytochemistry experiment.

Discogenic groin pain is referred pain which is transmitted by sympathetic nerves and appears in the area that was segmentally innervated by anterior rami of L1 and L, spinal nerves.