title: Increased sensitivity in the interaction of the dopaminergic/adenosinergic system at the level of the adenylate cyclase activity in the striatum of the "weaver" mouse.
abstract: The specific antagonistic interaction between dopamine D1 and adenosine A1 receptors (D1/A1), as well as between dopamine D2 and adenosine A2a receptors (D2/A2a) exist not only at the receptor/receptor level, but also at the level of the secondary messengers. In this study, we examined the possible changes in these interactions at the level of cAMP formation in membrane preparation from "weaver" mouse striatum (a genetic model of Parkinson disease), by using specific agonists of these receptors. We also examined in the striatum of the "weaver" mouse the interaction between D1 and D2 dopamine receptors. Our results showed that in the striatum of "weaver" mice: a) the cAMP synthesis induced by D1 receptor activation (SKF 38393), was significantly reduced compared to control mice, while A1 receptor activation (L-PIA) leaded to a more intense inhibition of the D1-induced cAMP-formation compared to the controls, b) the cAMP synthesis which was induced by A2a receptor activation (CGS 21680), was significantly increased compared to the control mice. The specific D2 receptor agonist Quinpirole, added in low concentrations, caused a significant reduction of the A2a-induced cAMP formation, which was not observed in the control mouse. Furthermore, the D1 receptor induced cAMP synthesis was significantly higher in control compared to "weaver" striatum, which was more efficiently downregulated by D2 receptor agonist Quinpirole. These results suggest that the sensitivity to D1 and A2a receptor agonists is altered and that the interaction between D1/A1 and D2/A2a receptors is enhanced in the striatum of the "weaver" mutation, while an uncoupling between D1 and D2 receptors was observed. Since the adenylate cyclase basal activity did not differ between "weaver" and control striatum, the above-mentioned changes seem to be due to alterations in the function of the adenosine/dopamine receptors and their coupling to the G-proteins.
authors: Laboratory of Physiology, Medical School, Department of Biology, University of Patras, 26500 Patras, Greece.
authors: Botsakis
authors: B
authors: K
authors: Laboratory of Human and Animal Physiology, Department of Biology, University of Patras, 26500 Patras, Greece.
authors: Tondikidou
authors: T
authors: V
authors: Laboratory of Human and Animal Physiology, Department of Biology, University of Patras, 26500 Patras, Greece.
authors: Panagopoulos
authors: P
authors: N
authors: Laboratory of Human and Animal Physiology, Department of Biology, University of Patras, 26500 Patras, Greece.
authors: Margariti
authors: M
authors: M
authors: Laboratory of Human and Animal Physiology, Department of Biology, University of Patras, 26500 Patras, Greece.
authors: Matsokis
authors: M
authors: N
authors: Laboratory of Physiology, Medical School, Department of Biology, University of Patras, 26500 Patras, Greece. Electronic address: rangel@med.upatras.gr.
authors: Angelatou
authors: A
authors: F
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D008818:Mice, Neurologic Mutants; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D019257:Quinpirole / Q000494:pharmacology; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D017447:Receptors, Dopamine D1 / Q000819:agonists / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000819:agonists / Q000378:metabolism*
chemical_list: D018491:Dopamine Agonists; D043705:Receptor, Adenosine A2A; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D000262:Adenylyl Cyclases
keywords: Dopamine/adenosine receptor interactions; Striatum; cAMP; “Weaver” mice