DIABETES AS AN AUTONOMIC NEUROPATHY MODEL

Abstract

Type of the study:The present study is a literature review about the diabetic neuropathy, specially the autonomic diabetic neuropathy, with emphasis on recent reports dealing with experimental models of autonomic neuropathies.Importance of the topic:Injury to the autonomic nervous system occurs in a variety of diseases, being the diabetes mellitus the most common. Alterations of the peripheral nervous system in genetically diabetic animals or in induced diabetic animals have been widely investigated, in an attempt to reproduce some of the characteristics of the human diabetic neuropathy. Several chemical agents are toxic to the beta-cells of the pancreas and Aloxane and Streptozotocin (STZ) are widely used to induce experimental diabetes. In general, STZ is more effective than Aloxane in inducing experimental diabetes. Although morphologic studies have been performed in somatic nerves, such as sural, fibular and tibial, in diabetic rats, information on autonomic nerves are scanty. Comments: Recently, we studied the morphology and morphometry of the aortic depressor nerve (ADN) in acute experimental diabetes in rats (15 days after STZ injection) and our results have demonstrated signs of axonal atrophy in 5 out of 10 nerves. A light microscopy study of the cervical vagus nerve of chronic (12 weeks after STZ injection) diabetic rats showed a discrete loss of the small myelinated fibers. Another study conducted in our laboratory showed a loss of the small myelinated fibers of the renal nerves in chronic diabetic rats, more evident than the observed on the vagus nerve. Nevertheless, the alterations of the  ADN (axonal atrophy) were similar to the observations for other somatic nerves, and different from the autonomic nerves. These results confirm the diabetic characteristics of a highly variable injury of peripheral nerves.