In vivo study of drug interaction with brain benzodiazepine receptor
The possibility of direct estimation of in vivo Bz receptor occupancy in brain was evaluated using C-11, or H-3-flumazepil (Ro15-1788). In animal experiments, 1 ..mu..Ci of H-3-Ro15-1788 was injected at 0.5 or 20 hr after i.v. injection of various dosage of clonazepam. Then radioactivity in cerebral cortex, cerebellum and blood at 5 min. after injection of the tracer was compared. Competitive inhibition of in vivo binding was clearly observed when clonazepam was pretreated at 0.5 hr before injection of the tracer. On the other hand, brain radioactivity was increased when clonazepam was administered at 20 hr before injection of the tracer. This increase in binding of H-3-Ro15-1788 might be caused by rebound of Bz receptor function by treatment with Bz agonist, and this rebound may have an important role in physiological function. Clinical investigation concerning drug interaction with brain Bz receptor was performed in normal volunteer and patients with neurological disorders. The distribution of C-11-Ro15-1788 in the brain of patients chronically treated with clonazepam were significantly heterogeneous. However, cerebral blood flow estimated with N-13 NH3 of these patients were normal.
- Research Organization:
- Div. of Clinical Research, National Institute of Radiological Sciences, Chiba
- OSTI ID:
- 6700943
- Report Number(s):
- CONF-850611-
- Journal Information:
- J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 26:5; ISSN JNMEA
- Country of Publication:
- United States
- Language:
- English
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62 RADIOLOGY AND NUCLEAR MEDICINE
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
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BIOLOGICAL MATERIALS
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BODY
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BRAIN
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NUCLEI
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ORGANS
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RADIOISOTOPES
RADIOPHARMACEUTICALS
RADIORECEPTOR ASSAY
REACTION KINETICS
RECEPTORS
TRACER TECHNIQUES
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