Ultrastructure of the sciatic nerve in diabetic rats.

Abstract

Animal models of diabetes have been widely used in experimental studies because they offer promise of new insights into human diabetes. Streptozotocin (STZ)–treated rats are an animal model of insulin‐dependent diabetes mellitus commonly used to study peripheral nervous system alterations even though the changes do not fully match the alterations observed in clinical conditions. Nevertheless, animal studies can be informative as to the changes that develop in the early stages of human diabetes. Male Wistar rats (n = 12) at 42 days of age were used. Induced diabetic animals (n=6) were fasted for 12 hours prior to being injected intraperitoneally with STZ (60mg/kg) in a single dose. Control animals (n=6) received vehicle. Ten weeks after STZ injection the animals were perfused intracardially with Karnovsky solution. Right and left sciatic nerves were dissected and processed for epoxy resin embedding. Samples were imaged with a transmission electron microscope. Large myelinated fibers with morphological signs of axonal atrophy in the sciatic nerves were readily observed. We also showed smaller myelinated fibers with sighs of demyelination. These results suggest that chronic STZ‐induced diabetes in rats caused alterations in the myelinated fibers as well as in the Schwann cells, compatible to the classic diabetes signs and symptoms reported in humans.Support: PNPD/CAPES; FAPESP; CNPq