A morphometric study on the longitudinal and lateral symmetry of the sural nerve in mature and aging female rats

• Published in: Brain research Vol. 1222; pp. 51 - 60
• Main Authors: Jeronimo, André, Jeronimo, Cláudia Além Domingues, Filho, Omar Andrade Rodrigues, Sanada, Luciana Sayuri, Fazan, Valéria Paula Sassoli
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 30-07-2008; Amsterdam Elsevier; New York, NY
• Subjects: Age Factors; Aging; Aging - physiology; Animals; Biological and medical sciences; Body Weight - physiology; Development. Senescence. Regeneration. Transplantation; Female; Female rat; Fundamental and applied biological sciences. Psychology; Morphology; Morphometry; Myelin Sheath - ultrastructure; Myelinated fibers; Nerve Fibers, Myelinated - ultrastructure; Neurology; Rats; Rats, Wistar; Sural nerve; Sural Nerve - cytology; Vertebrates: nervous system and sense organs; Aging; Myelinated fibers; Morphometry; Female rat; Morphology; Sural nerve; Senescence; Rat; Rodentia; Myelinated nerve fiber; Vertebrata; Mammalia; Animal; Female; Symmetry
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2008.05.055

Abstract Aging affects peripheral nerve function and regeneration in experimental models but few literature reports deal with animals aged more than one year. We investigated morphological and morphometric aspects of the sural nerve in aging rats. Female Wistar rats 360, 640 and 720 days old were killed, proximal and distal segments of the right and left sural nerves were prepared for light microscopy and computerized morphometry. No morphometric differences between proximal and distal segments or between right and left sides at the same levels were found in all experimental groups. No increase in fiber and axon sizes was observed from 360 to 720 days. Likewise, no difference in total myelinated fiber number was observed between groups. Myelinated fiber population distribution was bimodal, being the 720-days old animals’ distribution shifted to the left, indicating a reduction of the fiber diameters. The g ratio distribution of the 720-days old animals’ myelinated fiber was also shifted to the left, which suggests axonal atrophy. Morphological alterations due to aging were observed, mainly related to the myelin sheath, which suggests demyelination. Large fibers were more affected than the smaller ones. Axon abnormalities were not as common or as obvious as the myelin changes and Wallerian degeneration was rarely found. These alterations were observed in all experimental groups but were much less pronounced in rats 360 days old and their severity increased with aging. In conclusion, the present study indicates that the aging neuropathy present in the sural nerve of female rats is both axonal and demyelinating.