Saphenous nerve morphometry and aging: experimental study in rats.

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The saphenous nerve is a sensory nerve of the leg and foot, being the terminal branch of the femoral nerve, from the lumbar plexus. Because it is long and constant and presents a superficial pathway, it becomes a good experimental model for investigations of neuropathies. We know that the peripheral nerves undergo morphological and functional changes with aging. However, changes in the saphenous nerve as a consequence of aging have not been widely investigated. We investigated the probable changes in saphenous nerve morphology and morphometry in Wistar rats with different ages: 180 (n = 6), 360 (n = 6) and 720 (n = 6) days of life. Semithin cross sections (0.5 μm) of the nerves, stained with toluidine blue, were observed with a light microscope and the morphometry of fascicles and myelin fibers was performed through a computer program, taking into account the area and diameter of the fascicles, myelin fibers and their respective axons, number of myelin fibers and their density, and the myelin sheath area and G ratio of myelinated fibers. Statistical comparisons were performed between proximal and distal segments on the same side and between sides for segments of the same level at the same age, and between ages. Differences were considered significant when p <0.05. The presence of morphological changes in the myelin fibers (loss of circularity, demyelination, presence of myelin folds and balls) and in the endoneural capillaries (basement membrane thickening and endothelial hyperplasia) were visually detected in the nerves of 720 days old animals. Morphometry showed a reduction in the size of the axon and the G ratio, with a shift to the left of the G rate distribution histograms in animals with 720 days of life. Our results suggest the presence of axonal neuropathy due to aging.Support or Funding InformationFAEPA, CAPES and CNPqThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.