title: Effects of trihexyphenidyl and L-dopa on brain muscarinic cholinergic receptor binding measured by positron emission tomography.
abstract: The effects of pharmacological intervention on brain muscarinic cholinergic receptor (mAChR) binding were assessed in seven patients with Parkinson's disease by positron emission tomography and carbon-11 labelled N-methyl-4-piperidyl benzilate ([11C]NMPB). [11C]NMPB was injected twice, approximately 2 hours apart, in each patient, to assess the effect of single doses of 4 mg of trihexyphenidyl (n = 5) or 400 mg of L-dopa with 57 mg of benserazide (n = 2) on the binding parameter of mAChRs (K3). There was a mean 28% inhibition of K3 values in the brain in the presence of trihexyphenidyl, which was assumed to reflect mAChR occupancy. No significant change in K3 was observed in the presence of L-dopa. This study demonstrates the feasibility of measuring mAChR occupancy by an anticholinergic medication with PET.
authors.affiliation: Department of Neurology, School of Medicine, Chiba University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shinotoh
authors.forename: M
authors.initials: M
authors.lastname: Asahina
authors.forename: O
authors.initials: O
authors.lastname: Inoue
authors.forename: T
authors.initials: T
authors.lastname: Suhara
authors.forename: K
authors.initials: K
authors.lastname: Hirayama
authors.forename: Y
authors.initials: Y
authors.lastname: Tateno
mesh_terms: D000368:Aged; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014055:Tomography, Emission-Computed; D014282:Trihexyphenidyl / Q000494:pharmacology*
chemical_list: D011976:Receptors, Muscarinic; D007980:Levodopa; D014282:Trihexyphenidyl