Recurrent Laryngeal Nerve Alterations in Developing Spontaneously Hypertensive Rats

Author(s)

Rodrigues da Silva, Greice Anne ^[1] ; de Aguiar Mendes, Vania Alice ^[1] ; Genari, Adriana Borges ^[1] ; Castania, Jaci Ayrton ^[2] ; Salgado, Helio Cesar ^[2] ; Sassoli Fazan, Valeria Paula ^{[3, 1]}

Affiliation

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Neurosci & Behav Sci, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, BR-14049900 Ribeirao Preto, SP - Brazil

^[3] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Surg & Anat, BR-14049900 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: LARYNGOSCOPE; v. 126, n. 1, p. E40-E47, JAN 2016.
• Web of Science Citations: 1

Abstract

Objectives/Hypothesis: 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. Conclusion: 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. (AU)

• FAPESP's process: 13/01111-0 - Sensory and motor conduction velocity in spontaneously hypertensive rats
• Grantee: Valéria Paula Sassoli Fazan
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/20549-7 - New insights in cardiovascular regulation under physiological and pathophysiological condition
• Grantee: Helio Cesar Salgado
• Support Opportunities: Research Projects - Thematic Grants