Calibers and microtubules of nerve fibers: differential effect of undernutrition in developing and adult rats.
Sural nerves of 9-week-old rats undernourished since birth, and of adult rats food-restricted for 27 and 48 days, were studied to explore the effect of severe undernutrition on the caliber and microtubules of axons in growing and non-growing animals. In 9-week-old undernourished rats, the number and caliber of myelinated fibers were normal while the cross-sectional area of non-medullated fibers was 29% smaller than controls. By contrast, in adult undernourished rats the cross-sectional area of myelinated fibers was affected sooner and to a greater extent (-28%) than that of non-medullated fibers (-23%). Regardless of age, in both controls and in undernourished rats non-medullated fibers of equal caliber had similar microtubular content. The same was found in 3-microns myelinated axons. These findings indicate that food restriction affects proportionately caliber and microtubules of axons. It is proposed that the anatomy of the axon is in a dynamic equilibrium and that microtubules participate in the specification of the axonal caliber.
Faúndez
V
V
Unidad de Neurobiología Molecular, Facultad the Ciencias Biológicas, P. Universidad Católica, Santiago, Chile.
Cordero
M E
ME
Rosso
P
P
Alvarez
J
J
D000367:Age Factors; D000818:Animals; D002452:Cell Count; D005260:Female; D008297:Male; D008870:Microtubules / Q000502:physiology / Q000648:ultrastructure*; D009413:Nerve Fibers, Myelinated / Q000502:physiology / Q000648:ultrastructure*; D009748:Nutrition Disorders / Q000473:pathology* / Q000503:physiopathology; D051381:Rats; D011919:Rats, Inbred Strains; D013127:Spinal Nerves / Q000473:pathology*; D013497:Sural Nerve / Q000473:pathology* / Q000503:physiopathology