Neuro,ocience Letters, 34 (1982) 227-231 Elsevier Scientific Publishers lrel:.~td Ltd. 227 ACUTE. SUBCORTICAL LESIONS MODIFY CORTICAL MUSCARINIC RECEPTORS IN HUMAN BRAIN L. BRACCO, R. CORRADETTI* and L. AMADUCCI Department of Neurology, University of Florence, Viale G.B. Morgagni 85, 50134 Florence (Italy) (Received July 23rd, 1982; Accepted November 8th, 1982) Key words: [3Hlquinuclidinylbenzilate - human brain - muscarinic receptors - choline acetyl- transferase - cerebral cortex - stroke Post-mortem determinations of muscarinic cholinergic receptor rara meter, hy means of binding pro- cedures were carried out in human brains. In patients who died from internal caps~de stroke a significant increase in cortical (Brodmann area 8) muscarinic receptor density was prese:tt when compared to non- neurological :ontrols. No significant changes were detected in cortical choline acetyltransferase. Subcor- tical structures such as thalamus and caudate nucleus seemed to undergo opposite effects. It is suggested that acute interruption of fibers ascending to the cortex from subcortical areas can alter .~nuscarinic recep- tor properties in the cerebral cortex. Binding studies with the potent muscarinic antagonist [3H]quinuclidinylbenzilate ([3H]QNB) have been extensively used to characterize muscarinic receptor properties [I 1, 13]. Recent studies have shown that muscarinic receptors, as measured by the specific binding of [3HIQNB, are modulated by cholinergic input [1, 4, 10, 191. Although the evidence of receptor plasticity after brain lesions in laborato"y animals is controversial [9, 12, 18], recent studies have shown that, in the rat, sub- cortical lesions are able to modify receptor parameters [151 as well as functional cholinergic markers [16] in the cerebral cortex. However, to date, only few investiga- tions have been carried out to study changes in muscarinic receptor parameters after spontaneous diseases of human brain. Most of them, moreover, were dealing with chronic diseases such as Hungtington's chorea [201 or Alzheimer's disease [3, 221. Since an increasing bulk of evidence has been provided that the cortical cholinergic input originates from subcortical structures surrounding the internal capsule [6, 21, 23], we decided to investigate whether spontaneous acute lesions in this area due to stroke were able to change these receptors' parameters in the human brain. Control cases were subjects whose age ranged between 47 and 83 years (mean +_. * Permanent address: Departmet, t of Pharmacology, University of Florence, Italy. 0304-3940/82/0000-0000/$ 02.75 © 1982 Elsevier Scientific Publishers Ireland Ltd.