Chemical kindling enhances the Schaffer collateral-CAl pyramidal cell synaptic transmission in anesthetized rats

Epilepsy is one of the common disorders in human community. Clinical observations have shown that epileptic patients have often difficulty in learning and memory. Kindling is a laboratory model for studying epilepsy and its complications. This experiment was designed to study the effect of chemical kindling on Schaffer collateral-CA1 pyramidal cell synaptic transmission using pentylenetetrazole in urethane-anesthetized rats. Experiments were carried out on the hippocampal CA1 region from control and kindled rats at two periods post-kindling, i.e. 48-144 h (early phase) and 30-33 day (long-lasting phase). Population spike (PS) was recorded at stratum pyramidale following stimulation of the stratum fibers. The results showed that 48-144 h after kindling, the slope of population excitatory post-synaptic potential (pEPSP), the PS amplitude and spike latency in CA1 region of kindled rats were not significantly different than that of control. In contrast, 30 to 33 days after kindling, the amplitude of PS was significantly greater than that of control (p<0.01). These results suggest that chemical kindling entails long lasting changes in the function of CA1 that appear as enhanced excitability after one month