Behavioral and physiological studies of seizures induced by systemic injection of metrazol in chickens

The influence of systemically administered Metrazol on behavior, electroencephalogram and body temperature has been studied in young and adult chickens. Distinct convulsions were induced by 30--50 mg./kg. Metrazol administered intravenously in adults: they consisted of an initial excited state, a tonic convulsion accompanied with opisthotonos, and finally, convulsive movements. During recovery from these convulsions, three distinct behaviors were observed: violent peck-like movement, watchful state and finally panting behavior. All of the birds receiving higher intravenous doses (60--100 mg./kg.) exhibited vigorous convulsions immediately after injection and death occurred in 100% of the birds receiving these doses. An intraperitoneal injection of 75--100 mg./kg. Metrazol produced typical convulsions in young and adult chickens. At these doses, convulsions consisted of an initial excited state, a tonic convulsion accompanied with opisthotonos, and convulsive movements which involved clonic and tonic phases. The threshold for evoking typical convulsions with intraperitoneal injection ranges between 50 and 60 mg./kg. Metrazol in young chickens. The intravenous threshold doses for evoking high amplitude (1--2 mV.) in the EEG of adult chickens was 60 mg./kg. Metrazol. High intraperitoneal doses of Metrazol(75-100 mg./kg.) produced typical spikes with large amplitude which were synchronous in the two hemispheres in both young and adult chickens. There was a marked increase in body temperature within 10 minutes after injection in all cases of 50 mg./kg. intravenous dose: maximum increase (at 40 min.) was 1.5 degrees C. as compared with controls, however, it decreased rapidly with panting behavior. The highest does (100 mg./kg.) produced a maximum increase in body temperature of 3 degrees C. Discussion of epileptic seizure susceptibility to Metrazol in aves, in the light of phylogenesis, is discussed.