In vivo studies of opiate receptors
To study opiate receptors noninvasively in vivo using positron emission tomography, techniques for preferentially labeling opiate receptors in vivo can be used. The rate at which receptor-bound ligand clears from the brain in vivo can be predicted by measuring the equilibrium dissociation constant (KD) at 37 degrees C in the presence of 100 mM sodium chloride and 100 microM guanyl-5'-imidodiphosphate, the drug distribution coefficient, and the molecular weight. A suitable ligand for labeling opiate receptors in vivo is diprenorphine, which binds to mu, delta, and kappa receptors with approximately equal affinity in vitro. However, in vivo diprenorphine may bind predominantly to one opiate receptor subtype, possibly the mu receptor. To predict the affinity for binding to the opiate receptor, a Hansch correlation was determined between the 50% inhibitory concentration for a series of halogen-substituted fentanyl analogs and electronic, lipophilic, and steric parameters. Radiochemical methods for the synthesis of carbon-11-labeled diprenorphine and lofentanil are presented.
- Research Organization:
- Johns Hopkins Medical Institution, Division of Nuclear Medicine, Baltimore, MD
- OSTI ID:
- 6800335
- Journal Information:
- Ann. Neurol.; (United States), Journal Name: Ann. Neurol.; (United States) Vol. 15 Suppl; ISSN ANNED
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ANALGESICS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
BRAIN
CARBON 11
CARBON ISOTOPES
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
DRUGS
EMISSION COMPUTED TOMOGRAPHY
EVEN-ODD NUCLEI
IN VIVO
ISOTOPES
LABELLING
LIGHT NUCLEI
MINUTES LIVING RADIOISOTOPES
NARCOTICS
NERVOUS SYSTEM
NUCLEI
OPIUM
ORGANS
POSITRON COMPUTED TOMOGRAPHY
RADIOISOTOPES
RECEPTORS
TOMOGRAPHY