Imaging opiate receptors with positron emission tomography

Conference · Sun Jan 01 04:00:00 EST 1984 · J. Nucl. Med.; (United States)

OSTI ID:6930039

Frost, J J; Dannals, R F; Ravert, H T; Wilson, A A; Wong, D F; Links, J M; Burns, H D; Kuhar, M J; Snyder, S H; Wagner, Jr, H N

Opiate receptors exist in the mammalian brain and are thought to meditate the diverse pharmacological actions of the opiates, such as analgesia, euphoria, and sedation. The 4-carbomethoxyl derivatives of fentanyl, such as lofentanil and R31833 (4-carbomethoxyfentanyl) bind to the opiate receptor with high affinity. C-11 R31833 was synthesized by reacting C-11 methyl iodide with the appropriate carboxylate. Male ICR mice were injected intravenously with C-11 R31833 (5..mu..g/kg), killed 30 minutes later, and the brains rapidly dissected. The thalami, striata, and cerebral cortex are rich in opiate receptors, but the cerebellum contains a very low concentration of opiate receptors. The thalamus/cerebellum and striatum/cerebellum activity ratios, calculated per mg of wet tissue, were 4.1 and 5.2 respectively. Coinjection of 5mg/kg naloxone reduced the ratios to 1.1, which indicates that the preferential localization of C-11 R31833 in the thalami and striata is due to binding to opiate is due to binding to opiate receptors. A 22 kg anesthetized male baboon was imaged using the NeuroECAT after injection of 18.9 mCi of C-11 R13833 (0.50 ..mu..g/kg, specific activity 616 Ci/mmole at time of injection). From 15-70 minutes after injection preferential accumulation of activity could be seen in the thalami, caudate nuclei, and cerebral cortex and, conversely, low activity was demonstrated in the cerebellum. At one hour postinjection the maximum measured caudate/cerebellum activity ratio per pixel was 2.9. For the NeuroECAT the recovery coefficient for the baboon caudate is ca. 0.2-0.3, and therefore the actual caudate/cerebellum ratio is ca. 10-15.

• Research Organization: The Johns Hopkins Medical Institutions, Baltimore, MD
• OSTI ID: 6930039
• Report Number(s): CONF-840619-
• Conference Information: Journal Name: J. Nucl. Med.; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
AFFINITY
ANALGESICS
ANIMALS
APES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
BRAIN
CARBON 11
CARBON ISOTOPES
CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM DEPRESSANTS
COMPUTERIZED TOMOGRAPHY
DIAGNOSTIC TECHNIQUES
DIAGNOSTIC USES
DRUGS
EMISSION COMPUTED TOMOGRAPHY
EVEN-ODD NUCLEI
HALOGENATED ALIPHATIC HYDROCARBONS
IMAGE PROCESSING
IMAGES
INJECTION
INTAKE
IODINATED ALIPHATIC HYDROCARBONS
ISOTOPES
LABELLING
LIGHT NUCLEI
MAMMALS
MEMBRANE PROTEINS
METHYL IODIDE
MINUTES LIVING RADIOISOTOPES
NARCOTICS
NERVOUS SYSTEM
NUCLEI
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
POSITRON COMPUTED TOMOGRAPHY
PRIMATES
PROCESSING
PROTEINS
QUANTITY RATIO
RADIOISOTOPES
RECEPTORS
TOMOGRAPHY
USES
VERTEBRATES