REDISTRIBUTION OF AXOPLASM IN THE MOTOR ROOT IN EXPERIMENTAL DIABETES

Early experimental diabetes is associated with a reduction in axonal c aliber. To elucidate the changes of nerve caliber further, we investig ated the proximal and distal regions of the anterior root of rats afte r 5 weeks of streptozocin-induced diabetes. After vascular perfusion f ixation, the fifth lumbar motor root was excised and two 3-mm segments were isolated, one at the level of the spinal cord and one at the dor sal root ganglion. The areas of myelinated fibers and their axons were measured by point counting. Axons from diabetic mice were enlarged pr oximally as compared to the controls, and reduced distally. It has bee n hypothesized that the reduction in axonal caliber is caused by an im pairment of axonal transport of structural proteins rather than by osm otic shrinkage. Our findings indicate a redistribution of axoplasm in the nerves of the diabetic mice and support the hypothesis that change s in the axonal transport of neurofilaments are responsible for the st ructural changes seen in early diabetes. Similar changes could also pl ay a role in the development of neuropathy in man.