Ultrastructure and morphometry of the aortic depressor nerve in experimental diabetes: effects of insulin treatment

Abstract

Few reports deal with the diabetes effects on unmyelinated fiber morphology and how insulin treatment affects these fibers. The aortic depressor nerve (ADN) is the afferent arm of the baroreflex, and its myelinated fibers were already investigated in experimental diabetes (Fazan et al., 2006) while the unmyelinated fibers were never studied in this experimental model. We will evaluate the ultrastructural morphometric alterations in the ADN of rats, due to acute and chronic experimental diabetes and will study the effects of conventional insulin treatment in these alterations. Wistar rats will receive a single intravenous injection of streptozotocin (40mg/Kg) 15 days (acute) or 12 weeks (chronic) before the experiments. Control animals will receive vehicle. Insulin treated animals will receive a single subcutaneous injection of insulin on a daily basis. Under pentobarbital anesthesia the ADNs will be isolated and proximal and distal segments prepared for transmission electron microscopy as reported previously (Fazan et al., 1997; Fazan et al., 2001). Morphometry will be carried out with the aid of computer software and will take into consideration the number of the unmyelinated fibers and their density, as well as the area and diameter of these fibers. Endoneural blood vessels and myelinated fibers will also be investigated for ultrastructural alterations. (AU)