Aging and in vivo norepinephrine-uptake in mammalian brain

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Abstract
In order to examine the cellular effect of aging in the central nervous system, the regional distribution and the dynamic aspects of catecholamine metabolism in the brain were investigated. Results indicated that the endogenous norepinephrine (NE) content is lower in hypothalamus and brain stem of older rats (25 mo. n = 6) than younger rats (12 mo. n = 6). We have also observed in these animals that the age pigments were apparently absent in the brain tissue of young rats but become a very distinct feature for the old rats and that the catecholamine storing vesicles appeared to be less dense in the nerve terminals of old as compared with the young ones. 3H-NE was administered intracerebrally to mice of different age groups (4, 8, 12, 21 and 24 months) and the NE-uptake activity was examined by measuring the radioactive NE inside the isolated synaptosomes 5 min after 3H-NE injection. The result indicated that the young group (4 mo.) has highest uptake activity. The uptake activity decrease with the older mice and reached the lowest in the age group of 21–24 mo. The decrease in NE-uptake activity may be related to the deterioration of synaptosomal membranes.