Showing papers on "Aging brain published in 1980"

Differential changes in monoamine oxidase A and B activity in the aging rat brain.

Abstract: The activity of monoamine oxidase (MAO) was assayed in the brains of young adult (7-8 weeks old) and aging (95-104 weeks old) male Sprague-Dawley rats. When expressed per milligramme of tissue, total protein content was increased to a similar extent in whole brain and in all seven brain regions of the aging rat, whereas MAO A activity (assayed by using 5-hydroxytryptamine as substrate) was unchanged in whole brain but increased in the cerebellum, and fell in the brainstem, midbrain, hippocampus, and cortex; and MAO B activity (assayed by using beta-phenylethylamine as substrate) increased in whole brain and all regions, except the brainstem. Age-related changes in total protein, MAO A and MAO B were thus independent of each other. Kinetic studies indicated that the Vmax of MAO B was increased in aging rat brain, whereas the Km was unaltered. The increase in MAO B activity was restricted to the extrasynaptosomal mitochondrial fraction of the aging brain, whereas a reduction in MAO A activity was found in the intrasynaptosomal, but not the extrasynaptosomal mitochondrial fraction.

Neurochemical findings in the aging brain.

Abstract: We studied the influence of normal aging on 13 glycolytic enzymes, ATPase, carbonic anhydrase, and protein kinase in the human brain cortex and putamen, where there is a significant increase in soluble HK activity with age. This phenomenon is considered to be the result of an increased release of HK from mitochondrial membranes. A significant negative correlation of the activity of F6PK with age is observed in brain cortex and putamen. While the regulation of glycolysis imposes a limit on the formation of ATP with increasing age, no change appears to occur in the enzymatic capacity to break down ATP. Na+/K+-ATPase and Mg++-ATPase do not change with age. Carbonic anhydrase, important in the regulation of the pO2/pCO2 ratio in the brain tissue, demonstrates a significant decline with increasing age. Thus pCO2-dependent regulation of tissue pH, ionic transport processes, and cerebral blood flow regulation have the tendency to become more and more unstable. Protein kinase demonstrates a progressive age-dependent decline in cAMP-dependent activity, which is most significant in brain cortex and thalamus, followed by hippocampus, amygdala, and globus pallidus. The enzyme is of importance for the phosphorylation of the cell membrane and is thus of functional relevance for the nerve cell.