Muscarinic receptors and acetylcholinesterase activity in brain of patients with dementia

RESUMO

The present paper describes the determination of muscarinic receptor number ([3H]-N-methylscopolamine binding) and acetylcholinesterase activity in six brain areas (pre-central gyrus, post-central gyrus, hippocampus, caudate nucleus,lentiform nucleus and substantia inominata) of demented patients (diagnosed by screening tests and neurological evaluation) and age-matched controls.These was a significant increase in muscarinic receptors in the hippocampus and substanctia inominata (171.2 and 359.4fmol/mg protein, respectively) of the demented group as compared with controls (123.9 and 219.0 fmol/mg protein, respectively). No changes were observed in pre-and post-central gyrus, while a tendency towards decreased binding was detected in the caudate nucleus and lentiform nucleus of the demented group. Lower acetylcholinesterase activity was also detected in the demented group in all areas studied although the differences were significant only in the post-central gyrus, caudate nucleus and substantia inominata which showed a 49.21 and 25% decrease in enzyme activity respectively. The results are discussed in terms of a compensatory mechanism of presynaptic deficiency such as that occurring in Parkinson's disease