Blockade of Adenosine A2A Receptor Alleviates Cognitive Dysfunction after Chronic Exposure to Intermittent Hypoxia in Mice.

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is widely known for its multiple systems damage, especially neurocognitive deficits in children. Since their discovery, adenosine A(2A )receptors (A(2A)Rs) have been considered as key elements in signaling pathways mediating neurodegenerative diseases such as Huntington's and Alzheimer's, as well as cognitive function regulation. Herein, we investigated A(2A)R role in cognitive impairment induced by chronic intermittent hypoxia (CIH). Mice were exposed to CIH 7 h every day for 4 weeks, and intraperitoneally injected with A(2A)R agonist CG521680 or A(2A)R antagonist SCH58261 half an hour before IH exposure daily. The 8-arm radial arm maze was utilized to assess spatial memory after CIH exposures.To validate findings using pharmacology, the impact of intermittent hypoxia was investigated in A(2A)R knockout mice. CIH-induced memory dysfunction was manifested by increased error rates in the radial arm maze test. The behavioral changes were associated with hippocampal pathology, neuronal apoptosis, and synaptic plasticity impairment. The stimulation of adenosine A(2A)R exacerbated memory impairment with more serious neuropathological damage, attenuated long-term potentiation (LTP), syntaxin down-regulation, and increased BDNF protein. Moreover, apoptosis-promoting protein cleaved caspase-3 was upregulated while anti-apoptotic protein Bcl-2 was downregulated. Consistent with these findings, A(2A)R inhibition with SCH58261 and A(2A)R deletion exhibited the opposite result. Overall, these findings suggest that A(2A)R plays a critical role in CIH-induced impairment of learning and memory by accelerating hippocampal neuronal apoptosis and reducing synaptic plasticity. Blockade of adenosine A(2A) receptor alleviates cognitive dysfunction after chronic exposure to intermittent hypoxia in mice.