Morphological and morphometric study of the cervical vagus nerve myelinated fibers in acute and chronic experimental diabetes.

Abstract

The literature is scarce on pathological studies of the vagus nerve in patients known to have chronic autonomic diabetic neuropathy. Most of the morphological studies of the vagus nerve in experimental diabetes involve the study of the abdominal segment of this nerve or its mesenteric branches. In these studies, the authors demonstrate a presence of diabetic neuropathy and characterize the dying back process of this neuropathy. However, the morphological lesions described by these authors are exclusive of the unmyelinated fibers, since in these segments, the vagus nerve no longer presents myelinated fibers. The objective of the present study was to investigate the existence of morphological and morphometric alterations of the cervical vagus nerve myelinated fibers in acute and chronic experimental diabetes. Male Wistar rats received a single injection of streptozotocin (40mg/kg) 15 days (n = 6) or 12 weeks (n = 6) prior to the experiments. Control rats (n = 6) received equal volume of citrate buffer solution. Proximal and distal segments of the cervical vagus nerves had their fascicle and myelinated fibers and respective axons measured with the aid of computer software. The morphometric data comparison was performed between segments in the same nerve, sides and groups and differences were considered significant when p <0.05. Our results show that there are alterations in the morphology and morphometry of myelinated fibers and axons of the vagus nerve in diabetic animals, especially in their distal segments in both experimental groups. However, in the chronic diabetic group the alterations were more evident and committed the proximal segments. Thus, the results suggest a presence of axonal neuropathy in the vagus nerve due to experimental diabetes, and that alterations were progressive in a time dependent manner.Support or Funding InformationFAEPA, CAPES and CNPqThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.