Memory deficits induced by chronic cannabinoid exposure are prevented by adenosine A_2AR receptor antagonism

Patients under cannabis-based therapies are usually chronically exposed to cannabinoids. Chronic treatment with a cannabinoid receptor agonist, WIN 55,212–2, affects brain metabolism and modifies functional connectivity between brain areas responsible for memory and learning. Therefore, it is of uttermost importance to discover strategies to mitigate the negative side-effects of cannabinoid-based therapies. Previously, we showed that a single treatment with the synthetic cannabinoid WIN 55,212-2 disrupts recognition memory, an effect mediated by cannabinoid receptor 1 (CB₁R) and cancelled by concomitant administration of adenosine A_2A receptor (A_2AR) antagonists. We herein evaluate if memory deficits induced by chronic exposure to WIN 55,212–2 can also be reverted by A_2AR antagonism, and assessed the synaptic mechanisms that could be involved in that reversal. We show that chronic administration of KW-6002 (istradefylline) (3 mg/kg/28days) reverts memory deficits (evaluated through the Novel Object Recognition Test) induced by chronic cannabinoid exposure (WIN 55,212–2, 1 mg/kg/28 days). Long Term Potentiation (LTP) of synaptic potentials recorded from the CA1 area of the hippocampus was impaired by WIN 55,212–2 (300 nM), an effect partially rescued by the A_2AR antagonist, SCH 58261 (100 nM). Chronic administration of KW-6002 or WIN 55,212-2 did not affect A_2AR or CB₁R binding in the hippocampus and in the prefrontal cortex. These results, showing that A_2AR antagonism can still revert memory deficits after chronic administration of a cannabinoid, an effect that involves mitigation of synaptic plasticity impairment, strongly indicate that adenosine A_2ARs are appropriate targets to tackle side-effects of putative therapies involving the activation of cannabinoid receptors.