OBJECTIVE: The influence of dose of low power lasertherapy (AsGaAl, 830 nm) on the regeneration of the fibular nerve of rats after a crush injury was evaluated by means of the functional gait analysis and histomorphometric parameters. METHODS: Controlled crush injury of the right common fibular nerve, immediately followed by increasing doses (G1: no irradiation; G2: simulated; G3: 5 J/cm2; G4: 10 J/cm2; G5: 20 J/cm2) laser irradiation directly on the lesion site for 21 consecutive days. Functional gait analysis was carried out at weekly intervals by measuring the peroneal/fibular functional index (PFI). The animals were killed on the 21st postoperative day for removal of the fibular nerve, which was prepared for the histomorphometric analysis. RESULTS: The PFI progressively increased during the observation period in all groups, without significant differences between them (p>0.05). The transverse nerve area was significantly wider in group 2 than in groups 3 and 4, while fiber density was significantly greater in group 4 than in all remaining groups. CONCLUSION: The low power AsGaAl laser irradiation did not accelerate nerve recovery with any of the doses used. Level of Evidence I, Therapeutic Studies Investigating the Results of Treatment.

Previous data from our laboratory showed that the sural nerve from 20 weeks old spontaneously hypertensive rat (SHR) present alterations of myelinated fibers and endoneural vessels. To investigate whether these differences were caused by hypertension or were due to strains differences, the aim of the present study was to compare the aspects of the sural nerve from newly weaned SHR, which had not developed hypertension, with WKY. Rats aged 5 weeks (N=6 in each group) were used. After arterial pressure and heart rate recordings, right and left sural nerves were removed and prepared for light microscopy. Morphometric analysis was performed with the aid of computer software. Arterial pressure levels were similar between SHR and WKY. There were no differences in morphological and morphometric parameters of fascicular area, myelinated fiber number and density in both strains. Nevertheless, the morphometric parameters of myelinated fibers were different between SHR and WKY, despite no alterations on the endoneural vascularization in both strains. These results are suggestive of intrinsic differences on the myelinated fibers between SHR and WKY even before the development hypertension.

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.Suplementary dataA history of the beginning of the investigation of the “hypertensive neuropathy” will be presented with first results from the aortic depressor nerve and the evolution of the knowledge about how nerves are affected by hypertension, including results on the vagus nerve and phrenic nerve, and the association between hypertension and aging and hypertension and diabetes.Support or Funding InformationFAPESP, CNPq and FAEPA