Neurochemical Aspects of Parkinson’s Disease and the Dementing Brain Disorders: Relation to Brain Ageing. In: Nagatsu T, Fisher A, Yoshida M, editors. Basic, Clinical, and Therapeutic Aspects of Alzheimer’s and Parkinson’s Diseases. Boston: Springer New York; 1991. pp. 445-52. [DOI: 10.1007/978-1-4684-5844-2_89]

Brain monoamines in progressive supranuclear palsy--comparison with idiopathic Parkinson's disease

Like idiopathic Parkinson's disease (iPD), Progressive Supranuclear Palsy (PSP) is characterized, inter alia, by a pronounced non-overlapping loss of dopamine (DA) in caudate, putamen and substantia nigra. Unlike iPD, in PSP the striatal DA loss is more severe in the caudate than in the putamen; this may contribute to the higher frequency of cognitive deficits in PSP. In contrast to iPD, in patients with PSP the serotonin (5-HT) levels in the basal ganglia are not significantly reduced, thus resulting in a relative predominance of the inhibitory serotonergic influences on the motor behaviour in these patients. It is suggested that combination of levodopa with a 5-HT receptor blocker may substantially improve the (poor) responsiveness of patients with PSP to DA substitution therapy.

Cholinergic innervation of the amygdaloid complex in the human brain and its alterations in old age and Alzheimer's disease

The cholinergic innervation of the human amygdaloid complex was studied immunohistochemically with a choline acetyltransferase (ChAT) antibody in eight brains: five control and three with Alzheimer's disease (AD). All amygdaloid nuclei displayed ChAT-immunopositive axons and varicosities. The density of these axons reached levels that were higher than in any other part of the forebrain except for the striatum. The highest level of ChAT-immunopositive profiles was seen in the basolateral nucleus and the second highest in the lateral part of the central nucleus. The basomedial, accessory basal, and cortical nuclei, the amygdalohippocampal and cortico-amygdaloid transition areas, as well as the anterior amygdaloid area, showed a moderate density of ChAT-positive varicosities and fibers. The lateral nucleus displayed a relatively low density of cholinergic innervation, and there were only rare ChAT-positive fibers in the medial nucleus. Although the level of cholinergic innervation in the lateral nucleus was relatively lower than in many of the other amygdaloid nuclei, it was approximately equivalent to that of entorhinal cortex, a region that receives one of the heaviest cholinergic inputs in the cerebral cortex. The distribution of the cholinergic fibers as studied by ChAT immunohistochemistry was nearly identical to that observed with AChE histochemistry. Quantitative densitometry in control specimens showed that there was no decline of amygdaloid cholinergic input when middle-aged subjects were compared with senescent subjects. In AD there was a severe and regionally selective depletion of this innervation in the amygdaloid complex. The cortical, accessory basal, and lateral nuclei displayed the most severe loss of ChAT-positive profiles, whereas the basolateral, and especially the central, nuclei displayed relatively little change. There was no consistent relationship between the loss of cholinergic fibers and the density of amyloid plaques and neurofibrillary tangles in amygdaloid nuclei.

Aging produces a specific pattern of striatal dopamine loss: implications for the etiology of idiopathic Parkinson's disease

To examine the possible causal contribution of normal or accelerated aging to the neurodegenerative process of Parkinson's disease, we measured the influence of aging on subregional striatal dopamine and homovanillic acid levels in postmortem brain of 23 neurologically and psychiatrically normal human subjects 14-92 years old. We observed a significant decline in striatal dopamine levels and increase in the homovanillic acid/dopamine molar ratios with increasing age. The dopamine loss, on average, was of the same magnitude in the caudate nucleus and the putamen (-60% in the 84-year-old group as compared with the 22-year-old group), with the caudal component of both nuclei being more affected than the rostral subdivisions. The level of subregional dopamine metabolism, as measured by the homovanillic acid/dopamine ratio, in our young individuals (mean age, 22 years) was found to be inversely correlated to the degree of subregional dopamine loss suffered by the individuals in the older age groups. We conclude the following: (a) Striatal subdivisions with physiologically higher dopamine metabolism are not at a greater risk of suffering dopamine neuronal damage with advancing age, as would seem to be implied by the oxidative stress hypothesis; thus, formation of dopamine-derived oxy radicals in the human striatum appears unlikely to be a primary factor responsible for the age-related striatal dopamine loss. (b) The regional and subregional pattern of striatal dopamine loss in normal aging differs substantially from the pattern typically observed in idiopathic Parkinson's disease; therefore, the cause of idiopathic Parkinson's disease cannot be primarily an age-dependent neurodegenerative process.