Abstract
BackgroundThe sural nerve has been widely investigated in experimental models of neuropathies but information about its involvement in hypertension was not yet explored. The aim of the present study was to compare the morphological and morphometric aspects of different segments of the sural nerve in male and female spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. Rats aged 20 weeks (N = 6 in each group) were investigated. After arterial pressure and heart rate recordings in anesthetized animals, right and left sural 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.ResultsSignificant differences were observed for the myelinated fiber number and density, comparing different genders of WKY and SHR. 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. Morphological exam of the myelinated fibers suggested the presence of a neuropathy due to hypertension in both SHR genders.ConclusionsThese results indicate that hypertension altered important morphometric parameters related to nerve conduction of sural nerve in hypertensive animals. Moreover the comparison between males and females of WKY and SHR allows the conclusion that the morphological and morphometric parameters of sural nerve are not gender related. The morphometric approach confirmed the presence of neuropathy, mainly associated to the small myelinated fibers. In conclusion, the present study collected evidences that the high blood pressure in SHR is affecting the sural nerve myelinated fibers.
Highlights
The sural nerve has been widely investigated in experimental models of neuropathies but information about its involvement in hypertension was not yet explored
One or more fascicles were observed in the cross sections and general morphological characteristics of the sural nerve fascicles of WKY and spontaneously hypertensive (SHR) were similar to those described for female Wistar rats [13,14]
The comparison between strains indicated that the sural nerves from male and female SHR showed a larger number of collapsed blood vessels and/or vessels with thickening of the wall (Figure 1)
Summary
The sural nerve has been widely investigated in experimental models of neuropathies but information about its involvement in hypertension was not yet explored. The sural nerve in rats is one of the most distal sensory nerves to the foot and contains a small percentage of motor fibers for the intrinsic muscles of the lateral fingers It is the most common nerve used for investigating to infarcts, microaneurysms and ischemia [3]. In spite of the well documented influence of hypertension on the brain, data on the sensitivity of peripheral nerves in hypertension is scarce [3,4,5,6,7] Another important issue that is under investigation by several authors is the influence of gender in the alterations, injuries and recovery after a lesion of the nervous system. Few reports deal with the influence of gender and hypertension in morphological and/or morphometric differences in the peripheral nerves of mammals [6]
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