The effects of calcium channel antagonist nimodipine on end-plate vascularity of the degenerated intervertebral disc in rats.

The vascular channels at the end-plate of the intervertebral disc are very important in maintaining a healthy disc. With age, a reduction of the nutrition of the avascular nucleus pulposus is inevitable. On the other hand the calcium channel antagonist nimodipine has been shown to have a positive effect on blood flow in the region of the vertebral end-plate. To evaluate the effects of nimodipine on the end-plate vascularity in the degenerative discs, we have produced an experimental disc degeneration and evaluated the radiological and histopathological features of the end-plate of the degenerated discs. Adult rats were divided into 3 groups: control (n=5), operated degeneration (n=5), and nimodipine treatment (n=5). Using a posterior approach, a cut was made parallel to the end-plates in the posterior annulus fibrosus in 5 consecutive intervertebral discs between the 5th and 10th vertebral segments of the tails of adult Swiss Albino rats. At 8 weeks, 5 of these animals were treated with nimodipine. In each experimental group, 1 animal was examined using computed tomography (CT) to study the density of the cartilage end-plate of the disc. Then, the animals were sacrificed for subsequent histopathological evaluation. We found that the vascular channel counts and percentage areas from animals treated with nimodipine were higher than from both the non-operative control and operated degeneration groups, although these were not statistically different. Accordingly, the profile of the density histogram in the nimodipine-treated group showed a wide plateau, indicating an increase in the vascularity in this region. From our results, we suggest that nimodipine enhances vascularisation of the cartilage end-plate in the disc. It is possible that the increased proportion of vascular contacts at the end-plate has a beneficial effect in the nutrition of the disc. However, further experimental studies will be needed to determine the validity of this statement in animals or human beings.