Biomaterial Database

Quantitative film autoradiography of opiate agonist and antagonist binding in rat brain. 1983

W A Geary, and G F Wooten

The binding of a radiolabeled opiate agonist ([3H]etorphine) and antagonist ([3H]naloxone) was studied using quantitative film autoradiography of rat-brain sections labeled by in vitro dipping methods. The binding activities of both [3H]naloxone and [3H] etorphine were saturable in three brain regions: noncluster striatum, nucleus accumbens and cingulate cortex. Eadie-Hofstee analysis of these regions yielded the following binding affinities and capacities: noncluster striatum binding affinity (KD) +/- S.E. = 1.59 +/- 0.23 nM, maximal binding capacity (Bmax) +/- S.E. = 28.3 +/- 1.9 fmol/mg, S.D. error of the raw data (Erad) = 6.4%; nucleus accumbens, KD +/- S.E. = 1.74 +/- 0.28 nM, Bmax +/- S.E. = 73.3 +/- 5.2 fmol/mg, S.D. (Erad) = 6.2%; cingulate cortex, KD +/- S.E. = 1.44 +/- 0.15 nM, Bmax +/- S.E. = 37.6 +/- 1.4 fmol/mg, S.D. (Erad) = 2.5%. A KD +/- S.E. = 1.72 +/- 0.29 nM, Bmax +/- S.E. = 74.1 +/- 5.3 fmol/mg, S.D. (Erad) = 5.0% was found for [3H]etorphine binding in the noncluster striatum. Hill plots of both [3H]naloxone and [3H]etorphine binding in noncluster striatum demonstrated an absence of cooperativity with slopes of 1.01 and 1.07, respectively. Stereospecificity of binding was confirmed by competition for 2.0 nM [3H]naloxone in the noncluster striatum with a levorphanol IC50 = 5.5 nM and a dextrorphan IC50 greater than 1000 nM. Rank order potency for competition for 2.0 nM [3H]naloxone binding in noncluster striatum was etorphine greater than naloxone greater than levorphanol greater than morphine greater than dextrorphan. The regional order of binding activities (femtomoles per milligram +/- S.D.) for 2.0 nM [3H]naloxone was as follows: striatal clusters (111.1 +/- 24.5) greater than interpeduncular nucleus (77.8 +/- 10.1) greater than central nucleus of amygdala (64.5 +/- 9.7) greater than nucleus accumbens (34.4 +/- 6.9) greater than median raphe (24.4 +/- 6.1) greater than striatal noncluster (23.3 +/- 3.5) greater than superior colliculus striatum grieseum (22.2 +/- 4.0). Thus, quantitative film autoradiography of brain sections labeled in vitro may be used to characterize the pharmacological binding properties of ligands in many small brain regions not amendable to study in membrane preparations.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009019	Morphinans	Compounds based on a partially saturated iminoethanophenanthrene, which can be described as ethylimino-bridged benzo-decahydronaphthalenes. They include some of the OPIOIDS found in PAPAVER that are used as ANALGESICS.	Morphinan
D011869	Radioligand Assay	Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).	Protein-Binding Radioassay,Radioreceptor Assay,Assay, Radioligand,Assay, Radioreceptor,Assays, Radioligand,Assays, Radioreceptor,Protein Binding Radioassay,Protein-Binding Radioassays,Radioassay, Protein-Binding,Radioassays, Protein-Binding,Radioligand Assays,Radioreceptor Assays
D011957	Receptors, Opioid	Cell membrane proteins that bind opioids and trigger intracellular changes which influence the behavior of cells. The endogenous ligands for opioid receptors in mammals include three families of peptides, the enkephalins, endorphins, and dynorphins. The receptor classes include mu, delta, and kappa receptors. Sigma receptors bind several psychoactive substances, including certain opioids, but their endogenous ligands are not known.	Endorphin Receptors,Enkephalin Receptors,Narcotic Receptors,Opioid Receptors,Receptors, Endorphin,Receptors, Enkephalin,Receptors, Narcotic,Receptors, Opiate,Endorphin Receptor,Enkephalin Receptor,Normorphine Receptors,Opiate Receptor,Opiate Receptors,Opioid Receptor,Receptors, Normorphine,Receptors, beta-Endorphin,beta-Endorphin Receptor,Receptor, Endorphin,Receptor, Enkephalin,Receptor, Opiate,Receptor, Opioid,Receptor, beta-Endorphin,Receptors, beta Endorphin,beta Endorphin Receptor,beta-Endorphin Receptors
D001921	Brain	The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.	Encephalon
D005048	Etorphine	A narcotic analgesic morphinan used as a sedative in veterinary practice.	Ethorphine,M99
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001345	Autoradiography	The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)	Radioautography
D001667	Binding, Competitive	The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.	Competitive Binding
D013237	Stereoisomerism	The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)	Molecular Stereochemistry,Stereoisomers,Stereochemistry, Molecular,Stereoisomer