Large neurons in the neostriatum in Alzheimer's disease and progressive supranuclear palsy: a topographic, histologic and ultrastructural investigation

Large neurons in the neostriatum of patients with Alzheimer's disease (AD) and progressive supranuclear palsy (PSP) were investigated topographically, histologically and ultrastructurally. The number of large neurons whose nuclear area is greater than 101 microns2 was uniformly decreased in the neostriatum in PSP, but the decrease of these neurons in AD appeared to be more marked in the nucleus accumbens. Most of the remaining large neurons in both diseases contained neurofibrillary tangles (NFTs). In addition, some of the small neurons in PSP were positive for tau-immunostaining. Curly fibers were frequently observed in AD, but were absent in PSP. Ultrastructurally, NFTs in AD were composed mainly of paired helical filaments, whereas those in PSP contained straight tubules.

Quinolinic acid lesion of nucleus accumbens reduces D1 but not D2 dopamine receptors: an autoradiographic study

Information concerning the cellular localization of dopamine receptor subtypes in the nucleus accumbens (NAcc) was obtained using receptor autoradiographic analysis. Unilateral, stereotaxic injection of the axon-sparing neurotoxin, quinolinic acid, into the NAcc resulted in a prominent loss of dopamine D1 receptors (as labeled by [3H]SCH 23390). Contrarily, no appreciable decrement in D2 receptors (labeled by [3H]raclopride) could be identified within the same region of the NAcc. The findings support the view that accumbens D1 receptors are located postsynaptically on neurons or their processes, while D2 receptors within this nucleus are primarily located on afferent terminals.

[Morpho-chemical characteristics of the brain of rats genetically predisposed to catalepsy]

Cell organization of the cerebral cortex and striatum has been studied by+light optics and enzymatic activity of neuromediators catabolism--histochemically. In layers III and V of the sensomotor cortex and in the nucleus caudatus the number of neurons per unit area is increased, and their size is decreased. Volume of cytoplasm and nuclei of neurons in both layers is decreased, the latter--to less extent. The total amount of the perineuronal glia in the nucleus caudatus is also decreased at the expense of astroglia. In the cerebral cortex it is equal, but the ratio between astro-++- and oligodendroglia is changed. Acetylcholinesterase activity in the layers III and V of the sensomotor cortex is lower than in the control, while monoamine oxidase activity is kept at the control level. The genetically determined anomalies++ of growth and development of the cerebral cells is supposed to be considered as a structural base of the cataleptic state.

Possible increase of dopamine-beta-hydroxylase activity in the locus ceruleus of paranoid schizophrenic patients: a preliminary post-mortem study

Five schizophrenic brains and seven control brains were compared for phenylethanolamine-N-methyl-transferase and dopamine-beta-hydroxylase activities. The two groups were comparable in age, sex, and post-mortem delay before autopsy. A radioenzymatic assay showed a statistically significant increase of dopamine-beta-hydroxylase activity in the rostral part of the locus ceruleus in the schizophrenic brains.

Phencyclidine-induced activation of ventral tegmental A10 dopamine neurons is differentially affected by lesions of the nucleus accumbens and medial prefrontal cortex

The nucleus accumbens and medial prefrontal cortex contain high concentrations of phencyclidine (PCP) binding sites as well as supply inhibitory and excitatory inputs to the ventral tegmental area (VTA). Thus these two regions could be instrumental in mediating the unique bimodal response of A10 neurons to systemically administered PCP. Therefore we evaluated electrophysiologically the effects of lesions of these two areas on this pattern of response. In sham-lesioned controls, i.v. injections of PCP elicited a typical dose-dependent bimodal effect which was characterized by an activation of A10 firing at low dose (reaching a maximum of +44% at 1 mg/kg) followed by a slowing of this response with larger doses. However, in animals with kainic acid or radiofrequency lesions of the nucleus accumbens, PCP produced only a unimodal response resulting in sustained and elevated (+88% in kainate and +55% in radiofrequency lesioned groups) firing rates. Notably, neither basal activity nor the degree of activation of the A10's at doses of PCP less than 1 mg/kg were affected by the lesions. In contrast, excitotoxic destruction of the medial prefrontal cortex had no effect on the response of A10 neurons to PCP even though basal activity was slightly elevated in this group. These results suggest that the inhibitory component of the bimodal response of VTA neurons to systemic PCP is mediated via feedback pathways from the nucleus accumbens, but that the mesocortical prefrontal cortex does not appear to modulate any portion of this bimodal response.

Basal forebrain infarction. A clinicopathologic correlation

Following the repair of a ruptured anterior communicating artery aneurysm, a patient had a severe anterograde amnesia with sparing of other intellectual functions, apathy and loss of volition, altered arousal, and partial diabetes insipidus. Postmortem examination of the brain revealed bilateral destruction of the septal gray, nucleus accumbens, and nucleus of the diagonal band of Broca. Also involved in the lesion were inferior portions of the anterior limb of the internal capsule and globus pallidus. Discrete, microinfarcts were present in the paraventricular hypothalamic gray. Long-term therapy with desaminoarginine vasopressin nasal spray had no effect on the patient's neuropsychologic deficits.

Compulsive attentive behavior after lesion of the ventral striatum in the cat: a behavioral and electrophysiological study

Bilateral lesions of the nucleus accumbens in cat elicited the following changes: preservation in tests requiring focused attention, with difficulty to shift to other targets; paucity of movements, animals displaying moderate hypokinesia and loss of reaction to changes in the environment. These symptoms were accompanied by a significant increase in the amount of beta rhythms, an activity that has been shown to be concomitant with the development of focused attentive behavior. The observed behavioral and electrocortical modifications are opposite those that have been previously obtained in the same species after lesions of the ventral tegmental area.

Quantitative analysis of morphological features in Huntington's disease

In an electron microscopic study neuronal nuclear membrane indentations and astrocyte/neuron ratios in the nucleus accumbens, caudate nucleus and frontal cortex were counted in 30 Huntington's disease patients and 23 controls. Discriminant analysis was performed and resulted in a discriminant equation, which was able to recognize all controls correctly. Three Huntington patients were not correctly recognized, although in only one patient the probability of being a control was higher than being a Huntington patient. This discriminant equation was used in four choreatic patients with a negative family history. Two patients were indicated as controls, one patient as being a Huntington patient, and one as dubious. The diagnostic yield of discriminant analysis is discussed.

Basal ganglia and limbic system pathology in schizophrenia. A morphometric study of brain volume and shrinkage

The volume of several parts of the basal ganglia and of the limbic system was measured by planimetry of myelin-stained serial sections in postmortem brains of 13 schizophrenic patients and nine control cases. The medial limbic structures of the temporal lobe (amygdala, hippocampal formation, and parahippocampal gyrus) and the pallidum internum were significantly smaller in the schizophrenic group, whereas the pallidum externum showed only a modest trend toward volume reduction. The volumes of the putamen, nucleus caudatus, nucleus accumbens, and the bed nucleus of the stria terminalis did not differ between patients and controls. The volume reductions of the limbic temporal structures and of the pallidum internum of schizophrenics are interpreted as degenerative shrinkages of unknown etiology.

Neuronal distribution in the putamen in Huntington's disease

The numbers of neurons were counted in the ventral and dorsal anterior and ventral and dorsal posterior part of the putamen of 11 Huntington's disease and nine control patients. The process of neuronal cell loss in Huntington's disease proved to be unevenly spread throughout the putamen; the ventral anterior part was relatively spared as compared with the other parts of the putamen. A significantly higher number of neurons was found in the ventral part of the putamen in the controls.

Gamma-aminobutyric-acid deficiency in brain of schizophrenic patients

Gamma-aminobutyric acid (G.A.B.A.) was measured in the nucleus accumbens and thalamus of brains from patients who had died with schizophrenia or Huntington's chorea (H.C.) and from control subjects. Mean G.A.B.A. content was significantly reduced in both brain areas in schizophrenia and in H.C. Extraneous factors, such as age, interval from death to necropsy, cause of death, and drug use, did not readily explain the observed reduction in brain G.A.B.A. G.A.B.A. deficiency may be a biochemical characteristic of some forms of schizophrenia.