4.4. Maximal Electroshock Seizure Threshold Test

Maximal electroconvulsions were induced by applying a sinusoidal alternating current (50 Hz; duration 200 ms) via saline-soaked transcorneal electrodes using rodent shocker (type 221; Hugo Sachs Elektronik, Freiburg, Germany). During stimulation, mice were restrained manually and immediately following stimulation were placed in a transparent box for behavioral observation. Tonic extension of the hindlimbs (i.e., the rigid extension of the hindlimbs that exceeds a 90° angle with the body) was taken as the endpoint. The stimulus intensity was varied by an “up-and-down” method [45]. Each animal was stimulated only once at any given current intensity which was lowered or raised by 0.06-log intervals depending on whether the previously stimulated animal did or did not respond with the endpoint. The data obtained in groups of 20 animals were used to determine the threshold current causing hindlimb tonus in 50% of mice (CC₅₀ value with confidence limits for 95% probability).