Neuropathology

Neuropathological alterations in sciatic nerve have been modest in EDN. However, with more recent focus on nerve root, marked alterations in the spinal roots have been reported in long-standing streptozotocin-diabetic rats (16). We recently undertook a study addressing the status of vascular perfusion and neuropathology of DRG (17). Vascular perfusion and neuropathology evaluation of the lumbar spinal roots and DRG were studied in long-standing (duration of 12-18 months) streptozotocin-induced diabetic rats and age- and sex-matched control rats. We also undertook nerve conduction studies, including F wave recordings.

We have undertaken both perfusion-fixed and immersion-fixed ganglia. Light microscopically, changes of the myelin sheath in the dorsal and ventral roots and vacuolated cells in the DRG were the major findings, being significantly higher in diabetic rats than in control rats. The effects of the diabetic state on myelin splitting was greater in the dorsal than ventral roots. Electron microscopic studies revealed the consecutive changes of myelin from mild separation to severe ballooning of myelin with relative axonal sparing (Fig. 3). DRG cells showed vacuoles of all sizes with cristae-like residua, suggestive of mitochondria. These findings suggest that diabetes mellitus has a dual effect: It accelerates the normal age-related degenerative changes in the spinal roots and DRG and it also has a selective effect on the sensory neuron.

Nerve conduction studies showed markedly reduced conduction velocities in the distal nerve segments and prolonged F wave latency and proximal conduction time despite the shorter conduction pathway in diabetic rats. We suggest that the combination of hyperglycemia and ischemia results in oxidative stress and a predominantly sensory neuropathy.

Figure 3 Electron micrographs of representative ventral root fibers showing a progression of myelinopathy in experimental diabetes. (A) Myelin decompaction. (B) A rim of intact myelin surrounds degenerating myelin with early myelin balls and a de-nuted atrophic axon. (C) An atrophic axon is surrounded by myelin, showing residual rims separated by myelin degeneration and assuming a prominent honeycombed appearance. (D) A completely demyelinated axon is seen. (From Ref. 17.)

Figure 3 Electron micrographs of representative ventral root fibers showing a progression of myelinopathy in experimental diabetes. (A) Myelin decompaction. (B) A rim of intact myelin surrounds degenerating myelin with early myelin balls and a de-nuted atrophic axon. (C) An atrophic axon is surrounded by myelin, showing residual rims separated by myelin degeneration and assuming a prominent honeycombed appearance. (D) A completely demyelinated axon is seen. (From Ref. 17.)

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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