Association of chronic diabetes and hypertension in sural nerve morphometry: an experimental study

Author(s)

Sanada, Luciana Sayuri ^[1] ; Tavares, Marcelo Rodrigo ^[2] ; Sato, Karina Laurenti ^[3] ; Ferreira, Renata da Silva ^[1] ; Maia Neubern, Milena Cardoso ^[1] ; Castania, Jaci Ayrton ^[4] ; Salgado, Helio Cesar ^[4] ; Sassoli Fazan, Valeria Paula ^{[1, 5]}

Affiliation

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

^[2] Jose do Rosario Velano Univ, Dept Anat, Alfenas, MG - Brazil

^[3] Univ Fed Sergipe, Dept Phys Therapy, Aracaju, SE - Brazil

^[4] Univ Sao Paulo, Dept Physiol, Sch Med Ribeirao Preto, Ribeirao Preto, SP - Brazil

^[5] Univ Sao Paulo, Dept Surg & Anat, Sch Med Ribeirao Preto, Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: DIABETOLOGY & METABOLIC SYNDROME; v. 7, FEB 15 2015.
• Web of Science Citations: 4

Abstract

Background: Prospective studies have shown incidence rates of hypertension in diabetes mellitus to be three times that of subjects without diabetes mellitus. The reverse also applies, with the incidence of diabetes two to three times higher in patients with hypertension. Despite this common clinical association, the contribution of each isolated entity in the development of a neuropathy is still not well understood. The aims of the present study were to investigate the presence of peripheral neuropathy in spontaneously hypertensive rats (SHR) and SHR with chronically induced diabetes, using a morphological and morphometric study of the sural nerves. Methods: Female SHR and normotensive Wistar rats (WR), 8 weeks old, received a single intravenous injection of streptozotocin (STZ) through the tail vein. Controls from both strains received vehicle. Twelve weeks after the injection, sural nerves were dissected and prepared for light microscopy. Morphometry of sural nerve fascicles and myelinated fibers was performed with the aid of computer software. Results: The sural nerve myelinated fibers were highly affected by experimental diabetes in normotensive rats, causing mainly the reduction of the fiber size. Hypertensive rats showed characteristics of small fiber neuropathy and a severe reduction of the number and density or Schwann cells. The association between diabetes and hypertension caused an increase on the average size of the myelinated fibers, pointing to a small fiber loss, associated to axonal atrophy. Conclusions: Our study gives morphological support to the existence of a neuropathy due to hypertension, which is among one of the most common risk factors for diabetic neuropathy. The association between the two neuropathies showed to be a complex alteration, involving and including both, large and small fibers neuropathy. Hypertension caused, indeed, an exacerbation of the alterations already observed in experimental models of diabetic neuropathy. (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
• FAPESP's process: 09/16748-9 - Morphometry of phrenic nerves in spontaneously hypertensive rats
• Grantee: Valéria Paula Sassoli Fazan
• Support Opportunities: Regular Research Grants