Objective: To investigate effect of chronic transauricular kindled seizures on passive-avoidance test memory retention in rats.
Methods: Chronic transauricular kindled seizures was induced by repeated application of initially subconvulsive electrical stimulation through ear-clip electrodes once every 24 h until the occurrence of 3 consecutive clonic-tonic seizures. A passive avoidance test was used to measure memory retention ability. Morphological changes in neurons of hippocampal CA1 region was examined after HE staining. Histamine, gamma-aminobutyric acid (GABA) and glutamate levels in the hippocampus were measured by high performance liquid chromatography (HPLC).
Result: Chronic transauricular kindled seizures impaired passive-avoidance test memory retention in rats. The damaged CA1 neurons were observed and histamine content in the hippocampus markedly decreased 24 h after the end of kindling in the chronic transauricular kindled rats.
Conclusion: Chronic transauricular kindled seizure impaired passive-avoidance test memory retention, and it might be due to the damaged CA1 neurons and a decrease of histamine in the hippocampus induced by epilepsy.