Adenosine A1 receptors of amygdala has not anticonvulsant effects on piriform cortex kindled seizures in rats

Introduction: Adenosine is an endogenous anticonvulsant which exerts its anticonvulsant effects through adenosine A1 receptors. As the piriform/amygdala is a critical circuit for limbic seizure propagation, in this study the role of amygdala A1 receptors on piriform cortex kindled seizures was investigated. Materials and Methods: Rats were kindled by daily electrical stimulation of piriform cortex. In the first experiment fully kindled animals received intra-amygdala N6-cyclohexyladenosine (CHA 10-500 µM, a selective A1 receptor) or 2% lidocaine (for reversal neuronal inhibition) bilaterally. 5 min later, animals were stimulated and seizure parameters were measured. In the second experiment, the effect of daily microinjection of CHA (100 µM) into the amygdala on piriform cortex kindling rate was investigated. Results: Different doses of CHA had no effect on kindled seizure parameters. On the other hand, intra-amygdala 2% lidocaine reduced the kindled seizures severity. There were significant increase in stage 4 latency and decrease in stage 5 duration. Also, daily intra-amygdala CHA had no significant effect on kindling rate. Conclusion: The amygdala neuronal activity has a role in propagation of epileptic seizures from piriform cortex. Elimination of this activity by lidocaine decreases the severity of piriform cortex kindled seizures. However, the amygdala A1 receptors have no role in this regard.