Summary
Recently [3H]-CGS 21680 (2-[p-(2-carbonylethyl)-phenylethylamino]-5′-N-ethylcarboxamidoadeno-sine) has been identified as a selective adenosine A2-receptor agonist. In this study the binding of [3H]-CGS 21680 to 10 μm sections of rat neostriatum was investigated with quantitative autoradiography. Specific, saturable binding was detectable, and Scatchard analysis of saturation experiments gave estimates for K D and B max of 1.7 nM and 322 fmol/mg protein, respectively. The rank order of potency for inhibition of [3H]-CGS 21680 binding was 5′-N-ethylcarboxamidoadenosine (1.9 nM) > 2-chloroadenosine (18 nM) > R-N6-phenylisoprop-yladenosine (59 nM) > S-N6-phenylisoprophyladeno sine (460 nM) > 1,3-dipropyl-8-cyclopentylxanthine (700 nM). The binding of [3H]-CGS 21680 was sensitive to GTP, since 1 μM GTP reduced binding to 4.7% of control. These data support the identity of CGS 21680 as an agonist at high affinity adenosine A2-receptors and indicate these receptors in rat striatum are coupled to guanine nucleotide binding proteins.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bruns RF, Daly JW, Snyder SH (1980) Adenosine receptors in brain membranes: binding of N6-cyclohexyl[3H]adenosine and 1.3-diethyl-8-[3H]phenylxanthine. Proc Natl Acad Sci USA 77: 5547–5551
Bruns RF, Daly JW, Pugsley TA (1986) Characterization of the A2 receptor labeled by [3H]-NECA in rat striatal membranes. Mol Pharmacol 29:331–346
Cheng Y, Prusoff WH (1973) Relationship between the inhibition constant (K i) and the concentration of inhibitor which causes 50 percent inhibition (IC50) of an enzymatic reaction. Biochem Pharmacol 22:3099–3108
Daly JW (1985) Adenosine receptors. Adv Cyc Nuel Pro Phos Res 19:29–46
Fastbom J, Fredholm BB (1990) Regional differences in the effect of guanine nucleotides on agonist and antagonist binding to adenosine A1-receptors in rat brain, as revealed by autoradiography. Neuroscience 34:759–769
Fastbom J, Pazos A, Palacios JM (1987a) The distribution of adenosine A1 receptors and 5′-nucleotidase in the brain of some commonly used experimental animals. Neuroscience 22:813–826
Fastbom J, Pazos A, Probst A, Palacios JM (1987b) Adenosine A1 receptors in the human brain: a quantitative autoradiographic study. Neuroscience 22:827–839
Fredholm BB (1982) Adenosine receptors. Med Biol 60:289–293
Goodman RR, Snyder SH (1982) Autoradiographic localization of adenosine receptors in rat brain using [3H]-cyclohexyladenosine. J Neurosci 2:1230–1241
Goodman RR, Cooper MJ, Gavish M, Snyder SH (1982) Guanine nucleotide and cation regulation of the binding of [3H]-cyclohexyladenosine and [3H]-diethylphenylxanthine to adenosine A1 receptors in brain membranes. Mol Pharmacol 21:329–335
Hutchison AJ, Webb RL, Oei HH, Ghai GR, Zimmerman MB, Williams M (1989) CGS 21680C, an A2 selective adenosine receptor agonist with preferential hypotensive activity. J Pharmacol Exp Ther 251:47–55
Jarvis MF (1988) Autoradiographic localization and characterization of adenosine receptor subtypes. In: Leslie F, Altar CA (eds) Receptor localization: Ligand autoradiography. Liss, New York, pp 95–113
Jarvis MF, Williams M (1989) Direct autoradiographic localization of adenosine A2 receptors in the rat brain using the A2 selective agonist, [3H]-CGS 21680. Eur J Pharmacol 168:243–246
Jarvis MF, Jackson RH, Williams M (1989a) Autoradiographic characterization of high affinity adenosine A2 receptors in the rat brain. Brain Res 484:111–118
Jarvis MF, Schultz R, Hutchison AJ, Do UH, Sills M, Williams M (1989b) [3H]-CGS 21680, a selective A2 adenosine receptor agonist directly labels A2 receptors in rat brain. J Pharmacol Exp Ther 251:888–893
Lohse MJ, Lenschow V, Schwabe U (1984) Two affinity states of Ri adenosine receptors in brain membranes. Analysis of guanine nucleotides and temperature effects on radioligand binding. Mol Pharmacol 26:1–9
Lohse MJ, Elger B, Lindenborn-Fotinos J, Klotz K-N, Schwabe U (1988) Separation of solubilized A2 adenosine receptors of human platelets from non-receptor [3H]NECA binding sites by gel filtration. Naunyn-Schmiedeberg's Arch Pharmacol 337:64–68
Schwabe U, Trost T (1980) Characterization of adenosine receptors in rat brain by [3H]N6-phenylisopropyladenosine. Naunyn-Schmiedeberg's Arch Pharmacol 313:179–187
Ukena D, Poeschla E, Schwabe U (1984) Guanine nucleotide and cation regulation of radioligand binding to Ri adenosine receptors of rat fat cells. Naunyn-Schmiedeberg's Arch Pharmacol 326:241–247
Van Calker D, Muller M, Hamprecht B (1979) Adenosine regulates via two different types of receptors the accumulation of cAMP in cultured brain cells. J Neurochem 33:999–1005
Yeung SMH, Green RD (1983) Agonist and antagonist affinities for inhibitory adenosine receptors are reciprocally affected by 5′-guanylylimidodiphosphate or N-ethylmaleimide. J Biol Chem 258:2334–2339
Author information
Authors and Affiliations
Additional information
Send offprint requests to F. E. Parkinson at the above address
Rights and permissions
About this article
Cite this article
Parkinson, F.E., Fredholm, B.B. Autoradiographic evidence for G-protein coupled A2-receptors in rat neostriatum using [3H]-CGS 21680 as a ligand. Naunyn-Schmiedeberg's Arch Pharmacol 342, 85–89 (1990). https://doi.org/10.1007/BF00178977
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00178977