Axonal transport and nerve conduction and their relation to nerve polyol and myo-inositol levels in spontaneously diabetic BB/D rats.

This study examined orthograde axonal transport of choline acetyltransferase activity and motor nerve conduction velocity in insulin-treated diabetic and nondiabetic rats of the BB/D strain. In the same animals sciatic nerve contents of glucose, fructose, sorbitol, and myo-inositol were measured to determine whether any functional defects coexisted with polyol pathway activity or myo-inositol depletion. There were no differences between controls and diabetics in conduction velocity or the accumulation of choline acetyltransferase activity proximal to a 24-h sciatic nerve constriction. The latter finding implies no defect of axonal transport of the enzyme. At death the control rats were normoglycemic (mean blood glucose, 6.2 +/- 0.3 mmol/L) and the diabetic rats were moderately hyperglycemic (mean blood glucose, 18.1 +/- 1.3 mmol/L). The sciatic nerves of the diabetic rats showed marked elevation of glucose levels, moderate fructose accumulation and slight sorbitol accumulation. However, the myo-inositol levels were similar to those of control nerves. The findings suggest that, in BB rats with the degree of insulin treatment used here, myo-inositol levels were normal and that this co-existed with nerve conduction and axonal transport measurements which were similar to controls.