Adenosine A₁ receptor-mediated protection of mouse hippocampal synaptic transmission against oxygen and/or glucose...

Adenosine receptors are widely expressed in the brain, and adenosine is a key bioactive substance for neuroprotection. In this article, we clarify systematically the role of adenosine A₁ receptors during a range of timescales and conditions when a significant amount of adenosine is released. Using acute hippocampal slices obtained from mice that were wild type or null mutant for the adenosine A₁ receptor, we quantified and characterized the impact of varying durations of experimental ischemia, hypoxia, and hypoglycemia on synaptic transmission in the CA1 subregion. In normal tissue, these three stressors rapidly and markedly reduced synaptic transmission, and only treatment of sufficient duration led to incomplete recovery. In contrast, inactivation of adenosine A₁ receptors delayed and/or lessened the reduction in synaptic transmission during all three stressors and reduced the magnitude of the recovery significantly. We reproduced the responses to hypoxia and hypoglycemia by applying an adenosine A₁ receptor antagonist, validating the clear effects of genetic receptor inactivation on synaptic transmission. We found activation of adenosine A₁ receptor inhibited hippocampal synaptic transmission during the acute phase of ischemia, hypoxia, or hypoglycemia and caused the recovery from synaptic impairment after these three stressors using genetic mutant. These studies quantify the neuroprotective role of the adenosine A₁ receptor during a variety of metabolic stresses within the same recording system.NEW & NOTEWORTHY Deprivation of oxygen and/or glucose causes a rapid adenosine A₁ receptor-mediated decrease in synaptic transmission in mouse hippocampus. We quantified adenosine A₁ receptor-mediated inhibition during and synaptic recovery after ischemia, hypoxia, and hypoglycemia of varying durations using a genetic mutant and confirmed these findings using pharmacology. Overall, using the same recording conditions, we found the acute response and the neuroprotective ability of the adenosine A₁ receptor depended on the type and duration of deprivation event.