4.3. Maximal Electroshock Seizure Test

Electroconvulsions were evoked by an electric stimulus (an alternating current 25 mA, 50 Hz,500 V, 0.2 s) generated by a rodent shocker (Hugo Sachs Elektronik, Freiburg, Germany) and delivered via ear-clip electrodes. Tonic hindlimb extension (i.e., hindlimbs of animals outstretched 180 to plane of the body axis) was established as the endpoint. ED₅₀ is a median effective dose of the tested drug that protects 50% of mice against maximal electroshock-induced seizures. A dose–response curve was calculated on the basis of the percentage of mice protected according to Litchfield and Wilcoxon [60]. This experimental procedure has been described in detail in our previous studies [12,13,14].

C-11 was administered in doses that, per se, had no effect on seizure threshold in the maximal electroshock seizure threshold test. C-11 doses were selected based on previous studies where C-11 administered at a dose below 50 mg/kg protected mice from tonic hind limb extension after stimulation in MES test [15]. In addition, for ethical reasons, in accordance with the 3Rs rule, the maximal electroshock seizure threshold test (which would require at least additional 128 mice) was not performed.