Radioligand binding to adenosine receptors and adenosine uptake sites in different brain regions of normal and narcoleptic dogs
| Autor: | Miodrag Radulovacki, S.D. O'Connor, Emmanuel Mignot, W C Dement, S. Scott Bowersox, Marjorie Hawkins |
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| Rok vydání: | 1991 |
| Předmět: |
Agonist
Aging medicine.medical_specialty Adenosine medicine.drug_class G protein Clinical Biochemistry Population Adenosine-5'-(N-ethylcarboxamide) Biology Toxicology Biochemistry Radioligand Assay Behavioral Neuroscience Cataplexy Dogs GTP-Binding Proteins Thioinosine Internal medicine medicine Animals education Receptor Biological Psychiatry Narcolepsy Pharmacology Guanylyl Imidodiphosphate education.field_of_study Membranes Receptors Purinergic Brain Adenosine receptor Kinetics Endocrinology Xanthines Phenylisopropyladenosine Nucleoside Adenosine A2B receptor medicine.drug |
| Zdroj: | Pharmacology Biochemistry and Behavior. 38:1-6 |
| ISSN: | 0091-3057 |
| DOI: | 10.1016/0091-3057(91)90581-l |
| Popis: | The present study compares the characteristics of radioligand binding to adenosine receptors and adenosine uptake sites in 100- and 50-day-old normal and narcoleptic dogs. Binding to A 1 receptors was quantified using a selective A 1 agonist ([ 3 H]N 6 -[(R)-1-methyl-2-phenylethyl] adenosine, [ 3 H]R-PIA) and an antagonist ([ 3 H]dipropyl-8-cyclopentyl-xanthine, [ 3 H]CPX). Differences in the binding of [ 3 H]R-PIA and that of [ 3 H]5′-N-ethylcarboxamide adenosine ([ 3 H]NECA), which binds to both A 1 and A 2 receptors with similar affinities, were used to quantify A 2 receptors. Nucleoside transport sites were labeled with [ 3 H]nitrobenzylthioinosine ([ 3 H]NBTI), a potent inhibitor of nucleoside transport systems. The present study offered no evidence that either adenosine A 1 receptors and adenosine uptake sites in the frontal cortex or adenosine A 2 receptors in the putamen were altered in narcoleptic dogs. However, we found that adenosine A 1 receptors in the dog exist in different affinity states and that the affinity state in which the receptor is found depends on the brain region examined. A characterization of these low- and high-affinity sites was performed and results indicated that these sites cannot be explained by a single interaction of the A 1 receptor with a single G-protein population. |
| Databáze: | OpenAIRE |
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