Segmental demyelination in the distal peripheral nerves of chronically diabetic Chinese hamsters.

Abstract

Distal tibial nerves of 14 chronically diabetic and 6 control Chinese hamsters were examined using ultrastructural and teased whole-mount methods. Glucosuria was present for varying intervals up to 976 days, while 10 hamsters manifested ketonuria for intervals up to 551 days. Myelin internodal ensheathment patterns were analyzed from whole-mount preparations. A normal proportional relationship existed between myelin internodal length and fiber size in the peripheral nerves from control animals. Patterns of segmental demyelination were seen in the internode length/fiber size relationships of experimental animals. These changes were manifested by increased disparity of internode lengths along individual medullated fibers as well as by a generalized decrease of internode lengths, especially along large fibers. In addition, occasional fibers were seen undergoing acute axonal (Wallerian) degeneration in teased fiber preparations of diabetic animals. Variations in severity of structural alterations correlated with the length of diabetic state and were markedly increased in some animals with ketonuria. Examinations of some proximal sciatic nerves gave indications of a marked proximo-distal gradient in the manisfestations of the structural alterations in peripheral nerve. Electron microscopic evidence of demyelinative and remyelinative phenomena could be seen in diabetic hamsters. Both light and electron microscopic changes in diabetic animals were similar to those reported in diabetic neuropathy.