title: Sural nerve involvement in experimental hypertension: morphology and morphometry in male and female normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR).
abstract: BACKGROUND
  The 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.
  
  
  RESULTS
  Significant 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.
  
  
  CONCLUSIONS
  These 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.
authors.affiliation: Department of Neuroscience and Behavioral Neurosciences, University of São Paulo, Monte Alegre, Ribeirão Preto, Brazil.
authors.forename: Luciana Sayuri
authors.initials: LS
authors.lastname: Sanada
authors.forename: Andréa Lurdes
authors.initials: AL
authors.lastname: da Rocha Kalil
authors.forename: Marcelo Rodrigo
authors.initials: MR
authors.lastname: Tavares
authors.forename: Milena Cardoso Maia
authors.initials: MC
authors.lastname: Neubern
authors.forename: Helio Cesar
authors.initials: HC
authors.lastname: Salgado
authors.forename: Valéria Paula Sassoli
authors.initials: VP
authors.lastname: Fazan
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006973:Hypertension / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology* / Q000502:physiology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012737:Sex Factors; D013497:Sural Nerve / Q000473:pathology* / Q000503:physiopathology