The activities of glycolytic enzymes were determined in human autoptic temporal lobes from patients with different forms of dementia. For some enzymes (hexokinase, phosphofructokinase and phosphoglycerate mutase) the effect seen in dementia can be regarded as an intensification of the normal ageing affect. For other enzymes (aldolase, phosphoglucose isomerase, triosephosphate isomerase and lactate dehydrogenase) no changes in enzyme activities corresponding to those found in dementia are observed in the normal ageing process. These effects are most pronounced in the non-vascular Alzheimer cases. With the exception of triosephosphate isomerase and lactate dehydrogenase, enzyme activity is also reduced in bronchopneumonia. The effects of dementia and bronchopneumonia on the activities of glycolytic enzymes in human autoptic brain tissue are often difficult to distinguish.

Aged↗

PubMedDate not supplied

Stereological changes in the capillary network and nerve cells of the aging human brain.

Stereologic parameters of the capillaries and nerve cells of the brain cortex and putamen were investigated. Thirty-eight brains from subjects aged between 19 and 94 years were examined. All cases were free of metabolic, neurologic and psychiatric diseases. It is demonstrated that the capillary diameter remains unchanged during aging in both brain cortex and putamen. However, in the putamen the total capillary length per unit volume and the capillary volume fractions increase (approximately 60%) progressively with age. Consequently the mean inter-capillary distances in the putamen decrease (approximately 15%). These age-induced changes in the putamen indicate shrinking of subcortical brain structures. In contrast to those of the putamen, the morphometric data of the capillaries in the cortex remain unchanged during the aging process. Stereologic investigations of nerve cells in the brain cortex and putamen revealed that only in brains over 85 years of age can a significant decrease in nerve cell size be demonstrated. A correlation of all the data by a correspondence analytical procedure showed that only the surface/volume ratio of the capillaries correlates with the nerve cell size. This observation suggests a functional interaction between the nerve cells and the capillaries. From the data presented it becomes apparent that the shrinkage of the gyri in the aging brain is not a change in the volume of the cortex, but a decrease in the volume of subcortical structures.

Adult↗

PubMedDate not supplied

Investigations of the cholinergic deficit hypothesis in the hippocampus of the aged rat brain with physostigmine and scopolamine.

Using histochemically demonstrated acetylcholinesterase activity and (14)C-2-deoxyglucose uptake as the respective indices, a study was set up to determine whether cerebral (hippocampal) metabolism was stimulated by a cholinergic agonist and/or inhibited by a cholinergic antagonist. For this 36 12-month-old (adult) and 48 27-month-old (aged) Fischer 344 rats were given intraperitoneal injections of physostigmine 0.05, 0.1 or 0.2 mg/kg or scopolamine 0.01, 0.03 or 0.1 mg/kg for 5 days. In the aged rats there was a slight increase in acetylcholinesterase activity after physostigmine but no convincing evidence of enhanced (14)C-2-deoxyglucose uptake. In neither age group was glucose uptake significantly reduced by scopolamine; it was in fact increased, as was - slightly but significantly - acetylcholinesterase activity. Findings for acetylcholinesterase activity and (14)C-2-deoxyglucose uptake in aged Fischer 344 rats thus do not provide firm corroboration of physostigmine-induced stimulation of mental performance found in behavioural studies, while scopolamine did not adversely affect the hippocampal variables studied. It is concluded that cholinergic agents such as physostigmine and scopolamine have only a marginal effect on the functional and metabolic deficits associated with cerebral aging.

Journal Article↗