NICOTINIC RECEPTOR DISTRIBUTION IN THE HUMAN THALAMUS - AUTORADIOGRAPHICAL LOCALIZATION OF [H-3] NICOTINE AND [I-125] ALPHA-BUNGAROTOXIN BINDING

The thalamus plays a major role in relaying and transforming informati on that is relayed to the cortex and in turn modulates cortical output s. The reticular nucleus projects to the other thalamic nuclei, modula ting and integrating their activity. The distribution of high affinity nicotine and alpha-bungarotoxin (alpha BTX) receptors in the human th alamus has been investigated by radioligand autoradiography in post mo rtem human tissue. [H-3]nicotine binding in the human thalamus was hig h in most thalamic nuclei, especially in the lateral dorsal, the media l geniculate, lateral geniculate and anterior nuclei. The distribution of [I-125]alpha BTX binding was quite distinct from [3H]nicotine bind ing. [I-125]alpha BTX binding was generally lower (<0.26-11.62 fmol/mg protein compared with 6.68-36.17 fmol/mg protein for nicotine binding ) and concentrated in the reticular nucleus, with discrete groups of c ells displaying higher binding in the latter. These results indicate d ifferences between the distribution of nicotinic receptors in humans a nd those previously reported in mice and monkeys. Changes in high affi nity nicotine and alpha BTX receptors in the thalamus may contribute t o symptoms observed in neuropathological conditions associated with di sorders of perception and movement such as Dementia with Lewy Bodies, Alzheimer's Disease and Schizophrenia. (C) 1997 Elsevier Science B.V.