Neuronal nicotinic receptors in dementia with Lewy bodies and schizophrenia:: α-bungarotoxin and nicotine binding in the thalamus

Neuronal nicotinic receptors have been implicated in schizophrenia on the basis of the high incidence of tobacco smoking in patients, abnormalities in cytisine and alpha-bungarotoxin (alpha BGT) binding in the hippocampus, and linkage between auditory P50 deficits and the region of chromosome 15 coding the alpha 7 subunit, In another disease associated with psychosis, dementia with Lewy bodies (DLB), in which visual hallucinations predominate, reductions in nicotine binding have been identified in various cortical and subcortical regions. We investigated both alpha BGT and nicotine binding autoradiographically in different thalamic nuclei in autopsy brain tissue from patients with schizophrenia and DLB. alpha BGT binding in the reticular nucleus was moderately reduced (25%) in schizophrenia and more extensively reduced (50%) in DLB. There were no significant alterations in nicotine binding in schizophrenia, and in DLB, a trend towards moderate reductions in most nuclei reached significance in the lateral dorsal nucleus. It is concluded that widespread abnormalities of thalamic nicotine are not implicated in schizophrenia or DLB, but that reticular alpha BGT binding may be involved to a lesser acid greater extent in the pathophysiology or psychopathology of both disorders.