title: Recurrent laryngeal nerve alterations in developing spontaneously hypertensive rats.
abstract: OBJECTIVE
  It is well known that the recurrent laryngeal nerve not only innervates the larynx but also contains baroreceptor fibers, as demonstrated by physiological studies. Because hypertension has a negative impact on both peripheral nerve morphology and the baroreflex, we investigated the recurrent laryngeal nerve morphological alterations related to the development of hypertension.
  
  
  METHODS
  We compared morphological and morphometric aspects of different segments of the recurrent laryngeal nerve in male and female spontaneously hypertensive rats in different ages: 5, 8, and 20 weeks (n = 6 per group). Blood pressure and heart rate were recorded in anesthetized animals, followed by removal of the right and left recurrent laryngeal nerves for epoxy resin embedding and light microscopy analysis. Computer software was used for morphometric analysis.
  
  
  RESULTS
  The blood pressure was significantly higher in 20-week-old animals compared to those at 5 weeks. Body weight increased significantly with age, as did the nerve fascicles. For the myelinated fibers and respective axons, there was a reduction of fiber size, more evident on the axon, associated with a reduction of the small myelinated fibers percentage in animals with high blood pressure. Also, 20-week-old animals showed a significant reduction of the blood vessel percentage of occupancy compared to younger ages. No differences were observed between genders.
  
  
  CONCLUSIONS
  Hypertension development impaired axon growth, affecting mainly the small myelinated fibers. Males and females were affected equally. The alterations of the endoneural blood vessels probably played an important role on the small fibers alterations.
authors.affiliation: Department of Neuroscience and Behavioral Sciences, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Greice Anne Rodrigues
authors.initials: GA
authors.lastname: da Silva
authors.affiliation: Department of Neuroscience and Behavioral Sciences, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Vania Alice de Aguiar
authors.initials: VA
authors.lastname: Mendes
authors.affiliation: Department of Neuroscience and Behavioral Sciences, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Adriana Borges
authors.initials: AB
authors.lastname: Genari
authors.affiliation: Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Jaci Ayrton
authors.initials: JA
authors.lastname: Castania
authors.affiliation: Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Hélio Cesar
authors.initials: HC
authors.lastname: Salgado
authors.affiliation: Department of Neuroscience and Behavioral Sciences, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.|Department of Surgery and Anatomy, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Valéria Paula Sassoli
authors.initials: VP
authors.lastname: Fazan
mesh_terms: D000818:Animals; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure; D004195:Disease Models, Animal; D005260:Female; D006973:Hypertension / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D051381:Rats; D011918:Rats, Inbred SHR; D012009:Recurrent Laryngeal Nerve / Q000473:pathology* / Q000503:physiopathology
keywords: Recurrent laryngeal nerve; morphology; morphometry; myelinated fibers; spontaneously hypertensive rat