|Neuropharmacology. 2017 Feb 21. pii: S0028-3908(17)30075-8. doi: 10.1016/j.neuropharm.2017.02.021. [Epub ahead of print]|
Chronic and acute adenosine A2A receptor blockade prevents long-term episodic memory disruption caused by acute cannabinoid CB1 receptor activation.
Mouro FM1, Batalha VL2, Ferreira DG2, Coelho JE2, Baqi Y3, Müller CE4, Lopes LV2, Ribeiro JA1, Sebastião AM5.
1Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal.
2Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal.
3Pharma-Zentrum Bonn, Pharmazeutisches Institut, Pharmazeutische Chemie I, University of Bonn, Germany; Department of Chemistry, Faculty of Science, Sultan Qaboos University, Muscat, Oman.
4Pharma-Zentrum Bonn, Pharmazeutisches Institut, Pharmazeutische Chemie I, University of Bonn, Germany.
5Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Portugal; Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Portugal. Electronic address: email@example.com.
Cannabinoid-mediated memory impairment is a concern in cannabinoid-based therapies. Caffeine exacerbates cannabinoid CB1 receptor (CB1R)-induced memory deficits through an adenosine A1 receptor-mediated mechanism. We now evaluated how chronic or acute blockade of adenosine A2A receptors (A2ARs) affects long-term episodic memory deficits induced by a single injection of a selective CB1R agonist. Long-term episodic memory was assessed by the novel object recognition (NOR) test. Mice received an intraperitoneal (i.p.) injection of the CB1/CB2 receptor agonist WIN 55,212-2 (1 mg/kg) immediately after the NOR training, being tested for novelty recognition 24 h later. Anxiety levels were assessed by the Elevated Plus Maze test, immediately after the NOR. Mice were also tested for exploratory behaviour at the Open Field. For chronic A2AR blockade, KW-6002 (istradefylline) (3 mg/kg/day) was administered orally for 30 days; acute blockade of A2ARs was assessed by i.p. injection of SCH 58261 (1 mg/kg) administered either together with WIN 55,212-2 or only 30 min before the NOR test phase. The involvement of CB1Rs was assessed by using the CB1R antagonist, AM251 (3 mg/kg, i.p.). WIN 55,212-2 caused a disruption in NOR, an action absent in mice also receiving AM251, KW-6002 or SCH 58261 during the encoding/consolidation phase; SCH 58251 was ineffective if present during retrieval only. No effects were detected in the Elevated Plus maze or Open Field Test. The finding that CB1R-mediated memory disruption is prevented by antagonism of adenosine A2ARs, highlights a possibility to prevent cognitive side effects when therapeutic application of CB1R drugs is desired.