The relation between electrical self-stimulation sites and catecholamine-containing neurones in the rat mesencephalon

Résumé 72 électrodes implantées dans les mésencéphales des rats ont été examinées pour le comportement d'autostimulation. La majorité des sites positifs entourait le noyau interpédonculaire où se situent des neurones dopaminiques.

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Supported in part by grants from the U.K. Medical Research Council and the Mental Health Research Fund.     

The effect of unilateral and bilateral lesions in the locus coeruleus on the levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) in neocortex

Résumé Des lésions électrolytiques, soit unilatérales soit bilatérales, ont été pratiquées dans des cerveaux de rats, dans la région du locus coeruleus. Trois semaines après, la teneur en 3-méthoxy-4-hydroxyphénylglycol (MHPG) des deux cortices cérébraux a été analysée par chromatographie à gaz. Les lésions unilatérales ont réduit la teneur en MHPG du cortex ipsilatéral, et après les lésions bilatérales la réduction ent lieu dans les deux cortices.     

Neurotransmitter receptors as glycoproteins

Summary Incubation of calf brain membrane preparations with the plant lectins, concanavalin A and wheat germ agglutinin did not inhibit neurotransmitter receptor binding sites directly. Plant lectins did however protect these sites against subsequent trypsin digestion suggesting that neurotransmitter binding sites may be associated with glycoprotein structures.     

Location of neuronal tangles in somatostatin neurones in Alzheimer's disease

Senile dementia of the Alzheimer type is a chronic, progressive neuropsychiatric condition characterized clinically by global intellectual impairment and neuropathologically by the presence of numerous argyrophilic plaques and tangles. Neurochemical investigations have established loss of the cholinergic and aminergic projections to the cerebral cortex and a loss of the content of somatostatin, with preservation of cholecystokinin and vasoactive intestinal polypeptide, neuropeptides also located in cells intrinsic to the cortex. We describe here the relationship between cortical somatostatin immunoreactivity and the plaques and tangles of diseased tissue by immunocytochemical and silver impregnation techniques on paraffin-embedded tissue. In sections of Alzheimer's tissue, cortical somatostatin-immunoreactive perikarya exhibited morphological changes consistent with neuronal degeneration. Silver-stained material immunostained subsequently showed that many neurones containing tangles were also somatostatin positive. No such colocalization was observed using antisera to other neuropeptides. Our findings indicate that a subclass of somatostatin-positive neurones are affected selectively in Alzheimer's disease and that these neurones also contain neuronal tangles. Thus, destruction of somatostatin-containing neurones is an early and perhaps critical event in the disease process.