Fascicle morphometry of the recurrent laryngeal nerve in short term experimental diabetes.

Previous results from our laboratory [1] showed that 50% of the aortic depressor nerves (ADN), the afferent arm of the baroreflex, show alterations in early stages of induced diabetes in rats. The recurrent laryngeal nerves (RLN) are known to contain barorreceptor fibers as well and there are no reports on the morphology of the RLN in short term diabetes. Male Wistar rats received a single intravenous streptozotocin injection and control rats received vehicle. On the 15th day after the injections, rats were anesthetized for arterial pressure (AP) and heart rate (HR) recordings, prior to RLN removal. Proximal and distal segments of the right and left RLN were prepared for light microscopy morphometry, carried out with the aid of a computer software. Body weight increased significantly on the control s(309 ± 9 g) compared to the diabetics (200 ± 4 g). As expected, blood glucose levels were significantly high in the diabetic animals. Both the AP and HR were reduced in the diabetic group, attaining significant difference on the HR values. Fascicle morphometry parameters were not different between groups. We suggest that 15 days was not long enough to trigger detectable differences in the RLN fascicles. This difference with our previous findings in the ADN is probably due to the nerve size, since the ADN is much smaller than the RLN.