SEVERE RADICULAR PATHOLOGY IN RATS WITH LONGSTANDING DIABETES

There few pathological abnormalities in nerves from animals with diabe tes. Reported changes consist of mild distal axonal atrophy, axoglial disjunction and minimal segmental demyelination and remyelination. The se changes are seen in distal nerves but no studies of radicular patho logy in diabetic animals have been reported. We therefore studied peri pheral nerve and radicular pathology in rats with longstanding, severe , chemically-induced diabetes. We found marked interstitial edema and severe changes of myelin in the roots of diabetic rats, particularly i n the dorsal root. The earliest changes consist of myelin splitting, o ccurring at the intraperiod line. This progresses to myelin ballooning , accompanied by both tubulovescicular myelin degeneration and macroph age stripping, all of which tend to predominate in large myelinated fi bers. There is minimal axonal degeneration. Despite these severe chang es in nerve roots, the distal peripheral nerves show no discernible ed ema and only minimal myelin splitting without demyelination or axonal degeneration. The radicular changes are almost identical to those seen in much older nondiabetic animals. This suggests that they may repres ent an acceleration of the normal aging process, perhaps related to in creased glycation of myelin proteins induced by accumulation of glucos e rich interstitial endoneurial edema.