Peripheral neuropathy in mouse hereditary diabetes mellitus. I. Comparison of neurologic, histologic, and morphometric parameters with dystonic mice.

C57BL/KsJ db/db inbred mice have an hereditary autosomal recessive disease resembling in some respects maturity onset human diabetes mellitus. At 8--11 months of age, they displayed intermittent symptoms suggestive of a mild sensory neuropathy. These symptoms consisted of adduction of their hind limbs and flexing hind paws when raised by the tail, and inability to maintain their position on the roto wheel. Peripheral nerves and sensory ganglia of the diabetic mice were compared with those of the unafflicted littermates and studied with respect to Schwann cell counts and myelinated nerve fiber diameter measurements. In addition, teased fibers of peripheral nerves were compared for obvious changes in internodal distance and demyelination. Chromatolytic neurons were moe abundant in lumbosacral spinal ganglia of diabetic mice than in corresponding ganglia of controls or in more anterior spinal ganglia and trigeminal ganglia of diabetics. Histologic studies showed an increase in Schwann cell counts in longitudinal sections of peripheral nerves. A similar but larger increase was observed in peripheral nerves of mice affected with an hereditary sensory neuropathy, dystonia musculorum. A small but general decrease in myelinated fiber diameter was observed in sensory and motor nerves.