Decreased Incorporation of [3H]Inositol and [3H]Glycerol into Glycerolipids of Sciatic Nerve from the Streptozotocin Diabetic Rat

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Abstract
The incorporation of [3H]myo-inositol into individual phosphoinositides and of [3H]glycerol into glycerolipids was determined in sciatic nerve obtained from normal and streptozotocin diabetic rats and incubated in vitro. The uptake of inositol into lipid was .apprx. linear with time. More than 80% of the label was present in phosphatidylinositol with the remainder divided .apprx. equally between phosphatidylinositol phosphate and phosphatidylinositol-4,5-bisphosphate. Labeling was unchanged 2 wk after induction of diabetes, but was reduced by 32% after 20 wk of the disease. Glycerol incorporation occurred primarily into phosphatidylcholine and triacylglycerol and was depressed up to 45% into major phosphoglycerides in nerves from 2 and 20 wk diabetic animals. Triacylglycerol labeling was also substantially decreased. The reduction was comparable in intact and epineurin free nerve, suggesting that a metabolically active pool of this compound, which is sensitive to hyperglycemia and/or insulin deficiency, is located in or immediately adjacent to the nerve fibers. The considerable decline in incorporation of these lipid precursors in diabetic nerve may be related to impaired inositol transport and to decreased overall energy utilization of the tissue.