The role of adenosine A 1 and A 2A receptors of entorhinal cortex on piriform cortex kindled seizures in rats

Abstract

In this research the role of adenosine A 1 and A 2A receptors of the entorhinal cortex on piriform cortex kindled seizures was investigated. In piriform cortex kindled rats, N 6-cyclohexyladenosine (CHA), a selective A 1 receptor agonist, 1,3-dimethyl-8 cyclopenthylxanthine (CPT), a selective A 1 receptor antagonist, CGS21680 hydrochloride (CGS), a selective A 2A receptor agonist and ZM241385 (ZM), a selective A 2A 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, S 5D, and SD, and reduced S 4L 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 A 1 receptors of the entorhinal cortex has an anticonvulsant, but activation of A 2A receptors of this region has a proconvulsive effect on piriform cortex kindled seizures.