title: Combined antagonism of glutamate mGlu5 and adenosine A2A receptors interact to regulate alcohol-seeking in rats.
abstract: Adenosine and glutamate have been implicated as mediators involved in the self-administration of alcohol. In the present study we sought to determine whether adenosine receptors could interact with metabotropic glutamate receptors to regulate operant responding for alcohol and also the integration of the salience of alcohol-paired cues. Alcohol-preferring (iP) rats were trained to self-administer alcohol under operant conditions. The availability of alcohol was paired with an olfactory cue plus a stimulus light. Rats were examined under fixed ratio responding and also following extinction under a cue-induced reinstatement paradigm. Administration of the selective adenosine A2A receptor antagonist, SCH 58261, reduced fixed ratio responding for alcohol in iP rats in a dose-related manner. Furthermore, the combination of a subthreshold dose of SCH 58261 with a subthreshold dose of the mGlu5 receptor antagonist MTEP also reduced alcohol self-administration and increased the latency to the first reinforced response, suggesting a pre-ingestive effect. Moreover, this combination of SCH 58261 and MTEP also prevented the conditioned reinstatement of alcohol-seeking elicited by the re-presentation of cues previously paired with alcohol availability. In contrast, combinations of the selective adenosine A1 receptor antagonist, DPCPX, with either SCH 58261 or MTEP had no effect on alcohol responding. Collectively, these data suggest a functional interaction between adenosine A2A and mGlu5 receptors in relation to alcohol-seeking and the integration of the drug-related cues.
authors.affiliation: Department of Pharmaceutical Biology, Victorian College of Pharmacy, Monash University, Australia.
authors.forename: Cameron L
authors.initials: CL
authors.lastname: Adams
authors.forename: Michael S
authors.initials: MS
authors.lastname: Cowen
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Short
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lawrence
mesh_terms: D000241:Adenosine / Q000378:metabolism; D058916:Adenosine A1 Receptor Antagonists; D058917:Adenosine A2 Receptor Antagonists; D000428:Alcohol Drinking / Q000378:metabolism / Q000517:prevention & control*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002492:Central Nervous System Depressants / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects; D003463:Cues; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage*; D005108:Extinction, Psychological / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism; D023421:Models, Animal; D009043:Motor Activity / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time / Q000187:drug effects; D043682:Receptor, Adenosine A1 / Q000378:metabolism; D043705:Receptor, Adenosine A2A / Q000378:metabolism; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012646:Self Administration; D013844:Thiazoles / Q000494:pharmacology*; D013997:Time Factors; D014230:Triazoles / Q000494:pharmacology*; D014970:Xanthines / Q000494:pharmacology
chemical_list: C472365:3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine; C098657:5-amino-7-(2-phenylethyl)-2-(2-furyl)pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c)pyrimidine; D058916:Adenosine A1 Receptor Antagonists; D058917:Adenosine A2 Receptor Antagonists; D002492:Central Nervous System Depressants; D011725:Pyridines; D011743:Pyrimidines; D043682:Receptor, Adenosine A1; D043705:Receptor, Adenosine A2A; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D013844:Thiazoles; D014230:Triazoles; D014970:Xanthines; D000431:Ethanol; D018698:Glutamic Acid; C051360:1,3-dipropyl-8-cyclopentylxanthine; D000241:Adenosine