Phrenic Nerve Morphometry in Short Term and Long Term Experimental Diabetes

Abstract

The aim of the present study was to investigate the morphometric parameters of the phrenic nerve in short term and long term experimental diabetes. Male Wistar rats received a single intravenous injection of streptozotocin (40mg/Kg) 15 days (N=7) or 12 weeks (N=10) before the experiments. Controls rats (N=7 and N=4, respectively) received citrate buffer (vehicle). On the experimental day, rats were perfused with glutaraldehyde 2.5%, had the right and left phrenic nerves dissected and the proximal and distal segments prepared for light microscopy study as described previously (Rodrigues Filho & Fazan, 2006). Morphometry was performed with the aid of computer software and took into consideration the fascicle area and diameter, number of myelinated fibers and their density. Comparison was made between segments, sides and groups and differences were considered significant when p < 0.05. Our results show that the myelinated fiber number is similar between control groups but larger on both diabetic groups, compared to controls, particularly on the distal segments. This is suggestive of a “dying back” neuropathy, with signs of nerve regeneration.Support: CNPq, CAPES, FAPESP and FAEPAGrant Funding Source: CNPq, CAPES, FAPESP and FAEPA