The role of adenosine A1 and A2A receptors of entorhinal cortex on piriform cortex kindled seizures in rats

In this research the role of adenosine A1 and A2A receptors of the entorhinal cortex on piriform cortex kindled seizures was investigated. In piriform cortex kindled rats, N6-cyclohexyladenosine (CHA), a selective A1 receptor agonist, 1,3-dimethyl-8 cyclopenthylxanthine (CPT), a selective A1 receptor antagonist, CGS21680 hydrochloride (CGS), a selective A2A receptor agonist and ZM241385 (ZM), a selective A2A receptor antagonist were injected into the entorhinal cortex bilaterally. Five minutes later, animals were stimulated and seizure parameters were recorded. CHA (10 and 100 μM) decreased the afterdischarge duration (ADD), stage 5 seizure duration (S5D), and seizure duration (SD), and increased the latency to stage 4 of the seizure (S4L) significantly. Bilateral microinjection of CPT (100 μM) increased ADD, S5D, and SD, and reduced S4L significantly. Pretreatment of animals with CPT (50 μM) before CHA (100 μM), reduced the effect of CHA on seizure parameters. On the other hand, CGS (1 mM) increased only ADD. Bilateral microinjection of ZM had no effect on seizure parameters. However, pretreatment of animals with ZM (200 μM) before CGS (1 mM), eliminated the excitatory effect of CGS on seizure parameters. These results suggest that activation of A1 receptors of the entorhinal cortex has an anticonvulsant, but activation of A2A receptors of this region has a proconvulsive effect on piriform cortex kindled seizures.