Maximal Electroshock Seizure Threshold Test (MES-T) in Mice

The stimulus train was applied via ear-clip electrodes (sinusoidal pulses 4–14 mA, 50 Hz, 0.2 s duration) by means of a constant current stimulator (rodent-shocker type 221; Hugo Sachs Elektronik, March-Hugstetten, Germany). The stimulus intensity was varied by an up-and-down method in which the current was increased or decreased in 1 nA-steps if the preceding animal did not or did show tonic hindlimb extension, respectively (for further details, see [69]). Groups of 20 mice were used. Control groups, which received the corresponding vehicle, were tested together with the compound-treated groups on the same experimental day. Current intensity-effect curves were obtained on the basis of the number of animals responding with the endpoint at the corresponding current value. The results are calculated as convulsive current fifty (CC₅₀) values (current intensity in mA, necessary to produce tonic hindlimb extension in 50% of the mice tested) including the confidence limits for 95% probability.