Quantification of neuroreceptors in living human brain. v. endogenous neurotransmitter inhibition of haloperidol binding in psychosis.
Research output: Contribution to journal › Journal article › Research › peer-review
The half-inhibition concentration (IC50) of a drug indicates its ability to inhibit the binding of other ligands of a receptor. The authors used positron emission tomography to test the hypothesis that haloperidol's IC50 toward the binding of tracer N-[11C]methylspiperone ([11C]NMSP) in brain must be increased in patients in whom more dopamine is bound to receptors than in healthy volunteers. The IC50 of haloperidol was significantly elevated from 1.5 nmol/L in healthy volunteers and patients with bipolar disease without psychosis to 4.5 nmol/L in patients with schizophrenia or bipolar disease with psychosis. The higher IC50 values in psychosis are consistent with an 8-fold increased binding of dopamine and a 16-fold elevated concentration of synaptic dopamine in psychosis. At the 80% haloperidol blockade of the receptors, the calculated amount of neurotransmitter bound in the patients with psychosis declined to twice the value estimated in the nonpsychotic subjects, that is, 5 pmol cm(-3).
Original language | English |
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Journal | Journal of Cerebral Blood Flow and Metabolism |
Volume | 21 |
Issue number | 8 |
Pages (from-to) | 982-94 |
Number of pages | 12 |
ISSN | 0271-678X |
DOIs | |
Publication status | Published - 2001 |
Externally published | Yes |
ID: 14942314