Objective:To explore the age-related changes of the myelinated fibers

myelin sheath and the expression of myelin basic protein in the frontal region of the corpus callosum in old rats

and their relationship.Methods:The myelinated fibers and sheathes in the frontal region of corpus callosum of young and old-aged female Long-Evans rats were quantitatively studied using electron microscope and unbiased stereological techniques.Myelin basic proteins in the frontal region of corpus callosum of young and old-aged female rats were quantitatively studied using Western blot.Results:When compared with young female rats

the total volume of the frontal region of the corpus callosum and the total volume of the myelinated fibers in the frontal region of old corpus callosum were significantly degraded.The expression of 21.5 kD MBP was significantly decreased in old rats.The reduction of the expression of 21.5 kD MBP

the reduction of the total volume of the myelinated fibers and the total volume of the myelin sheathes were positively correlated.Conclusion:There is age-related atrophy of the frontal region of corpus callosum.The age-related changes of the myelinated fibers and MBP in the frontal region of corpus callosum may be related to the decline of frontal lobe functions with aging.