Ultrastructural and morphometric alterations in the aortic depressor nerve of rats due to long term experimental diabetes: Effects of insulin treatment

Author(s)

Oliveira, Fabricio S. ^[1] ; Nessler, Randy A. ^[2] ; Castania, Jaci A. ^[3] ; Salgado, Helio C. ^[3] ; Fazan, Valeria P. S. ^{[2, 3]}

Affiliation

^[1] Univ Estadual Maringa, Umuarama, Parana - Brazil

^[2] Univ Iowa, Cent Microscopy Res Facil, Iowa City, IA - USA

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

• Document type: Journal article
• Source: Brain Research; v. 1491, p. 197-203, JAN 23 2013.
• Web of Science Citations: 11

Abstract

Most of the reports about an altered baroreflex attribute this condition to the diabetic efferent neuropathy of the aortic depressor nerve (ADN) (afferent arm of the baroreflex less explored). We evaluated the ADN ultrastructural alterations caused by long term experimental diabetes and the effects of insulin treatment. Wistar rats (N=14) received a single intravenous injection of streptozotocin (40 mg/kg) 12 weeks before the experiment. Control animals (N=9) received vehicle (citrate buffer). Insulin treated animals (N=8) received a single subcutaneous injection of insulin daily. Under pentobarbital anesthesia the ADNs were isolated and had their spontaneous activity recorded. Afterwards, proximal and distal segments of the nerves were prepared for transmission electron microscopy study. Morphometry of the unmyelinated fibers was carried out with the aid of computer software. ADN of the diabetic animals showed axonal atrophy for myelinated fibers, with more pronounced alterations of the myelin sheath, such as myelin infolding and out folding, presence of myelin balls and very thin myelin sheath in relation to the axonal size, particularly for the small myelinated fibers becoming evident. No differences were observed in myelinated fiber number and their density, as well as on the fascicular area. Unmyelinated fiber number was significantly larger in the diabetic group while fiber diameter was significantly smaller compared to control. This result suggests axonal atrophy or, if associated to the larger number of fibers present in this group, could indicate fiber sprouting. These alterations were more evident in the distal segments of the nerves and were moderated by insulin treatment. (C) 2012 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 10/12518-6 - Morphologic evaluation and comparison between types of muscle fibers of the lateral and medial gastrocnemius and flexor halucis longus after painful stimulation in the neonatal period
• Grantee: Valéria Paula Sassoli Fazan
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/50389-6 - Cardiovascular regulation under physiological pathophysiological conditions
• 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