Valéria Paula Sassoli Fazan
University of São Paulo, Brazil
Title: Peripheral nerve injury due to hypertension is aggravated by diabetes
Biography
Biography: Valéria Paula Sassoli Fazan
Abstract
Statement of the Problem: Hypertension has a negative impact on both central and peripheral nervous system (PNS) morphology and function. For the central nervous system, brain atrophy, loss of nerve cells in cerebrocortical areas, and glial reaction were well documented. The PNS involvement in hypertension is under investigation in our laboratory for several years and the presence of a so called “hypertensive neuropathy” is documented with endoneurial vascular lesions, axonal atrophy and loss of small myelinated fibers. Hypertension is about twice more prevalent in diabetics as in non-diabetics. Despite this common clinical association, the contribution of each isolated entity in the development of neuropathy is still not well understood. We aimed 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.
Methodology: Female SHR, eight weeks old, received a single intravenous injection of streptozotocin (STZ) to induce diabetes. Normotensive Wistar-Kyoto (WKY) and non-diabetic SHR received vehicle. Twelve weeks after the injection, sural nerves were dissected and prepared for light microscopy and myelinated fibers morphometric study.
Findings: 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.
Conclusion & Significance: Association of hypertension and diabetes caused more pronounced changes than in the single disease models. The peripheral nerve disorder observed was a complex neuropathy, involving and including both, large and small fibers. Hypertension caused, indeed, an exacerbation of the alterations already observed in experimental models of diabetic neuropathy. Thus, hypertension associated with diabetes affect the structure of the PNS and that association of the two diseases results in an increased risk of nerve damage.
Recent Publications
1. da Silva G A, Mendes V A, Genari A B, Castania J A, Salgado H C and Fazan V P (2016) Recurrent laryngeal nerve alterations in developing spontaneously hypertensive rats. Laryngoscope 126(1):E40-7.
2. Sanada L S, Tavares M R, Sato K L, Ferreira R da S, Neubern M C, Castania J A, Salgado H C and Fazan V P S (2015) Association of chronic diabetes and hypertension in sural nerve morphometry: an experimental study. Diabetol Metab Syndr 7:9.
3. Oliveira F S, Nessler R A, Castania J A, Salgado H C and Fazan V P S (2013) Ultra structural and morphometric alterations in the aortic depressor nerve of rats due to long term experimental diabetes: effects of insulin treatment. Brain Res 1491:197-203.
4. Sanada L S, da Rocha Kalil A L, Tavares M R, Neubern M C, Salgado H C and Fazan V P S (2012) Sural nerve involvement in experimental hypertension: morphology and morphometry in male and female normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). BMC Neurosci 13:24.
5. Rodrigues A R, Ferreira R S, Salgado H C and Fazan V P S (2011) Morphometric analysis of the phrenic nerve in male and female Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). Braz J Med Biol Res 44(6):583-591.