Hypertensive Neuropathy: A New Clinical Entity?

Abstract

Hypertension is a main risk factor for stroke and vascular dementia and may cause important changes to the cerebrovascular tree, turning the brain more susceptible to infarcts, microaneurysms and ischemia. In spite of the well documented influence of hypertension on the brain, data on the sensitivity of peripheral nerves in hypertension is scarce. Our laboratory has been working for decades to help understanding how hypertension affects peripheral nerve morphology and function, using the spontaneously hypertensive rats (SHR) model. Spontaneously hypertensive rats (SHR), first inbred from Wistar Kyoto rats (WKY), are considered a good experimental model of human essential hypertension. The purpose of this study was to investigate the alterations on the morphology and morphometric data on sural, phrenic, vagus and recurrent laryngeal nerves of SHR, previous to the development of hypertension and with well‐established hypertension. Male and female SHR and normotensive WKY rats aged 5, 8 and 20 weeks (N = 6 in each group) were investigated. After arterial pressure and heart rate recordings in anesthetized animals, right and left sural, vagus, phrenic and recurrent laryngeal nerves were removed and prepared for epoxy resin embedding and light microscopy. Morphometric analysis was performed with the aid of computer software, and took into consideration the fascicle area and diameter, as well as myelinated fiber number, density, area and diameter. Nerves from young animals did not show differences between sides and genders. Significant differences were observed for the myelinated fiber number and density, comparing different genders of WKY and SHR in all nerves. Also, significant differences for the morphological (thickening of the endoneural blood vessel walls and lumen reduction) and morphometric (myelinated fibers diameter and G ratio) parameters of myelinated fibers were identified in nerves from adult hypertensive animals. Morphological exam of the myelinated fibers suggested the presence of a neuropathy due to hypertension in both SHR genders. These results indicate that hypertension altered important morphometric parameters related to nerve conduction in hypertensive animals. Moreover the comparison between males and females of WKY and SHR showed that the morphological and morphometric alterations due to hypertension are not gender related. The presence of a so called “hypertensive neuropathy” is documented with endoneural vascular lesions, axonal atrophy and loss of small myelinated fibers.Support or Funding InformationSupport: CNPq, FAPESP and FAEPAThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.