The functional rhythm is seen in a brain. It contains theta, beta, gamma rhythms which are related to memory and learning. Hippocampus has beta rhythm. The rhythm can be also induced in rat hippocampal slices with the application of the cholinergic agent carbachol. Hippocampus also has the pathological epileptic discharges. The discharges are often induced by hippocampal synchronized neurons. They are also induced in the slices with the application of GABAA receptor antagonist. There are two types of the discharges. One is an ictal discharge, and the other is an interictal discharge. Our previous work indicated that one of the antagonist picrotoxin (PTX), bicuculline (BIC), SR-95531 (GABAzine) induced the epileptic discharges, and the discharges are suppressed and turned into beta oscillation by carbachol. In the present study, we studied whether beta oscillation induced by carbachol has protection effect for inducing the epileptic discharges. The data were obtained from hippocampal slices (450-um thick) of male Wistar rats. The recording glass electrode (< 2 MΩ) was placed in the CA3 stratum pyramidale to record the epileptic discharges induced with the application of between 0.1 and 20 uM PTX, BIC, GABAzine. The discharges were induced with PTX above 0.2 uM. The interictal discharges were mainly induced between one and ten uM. The ictal discharges were induced by PTX above 2 uM. The similar results were also seen in slices with the application of BIC and GABAzine. These results suggest that disinhibition can induce the interictal and ictal discharges. But epileptic discharges by PTX were not induced in case that the slices were pre-treated by carbachol and beta oscillations were induced. The results of the application of BIC and GABAzine in beta oscillation were as well. Epileptic discharges were induced after the GABAA receptor antagonists were washed out, and only carbachol was applied. These results suggest that the beta oscillation was not affected with the application of PTX, BIC, GABAzine at the concentration which induces the epileptic discharges.