数種の工業中毒物質の中枢神経系におよぼす影響 : 動物における脳波の変化

Abstract

Effects of methanol, ethanol, n-propanol, carbon disulfide and o-phthalodinitrile on the electrical activities of the central nervous system of cats and rabbits were studied. Also, from the results of the present investigation and of the pervious one dealing with the effect of nitroglycol, the use of the electroencephalographic technique to the study of industrial toxicology was discussed. 1. Methanol, ethanol and n-propanol: Oral administration of 1-3ml-kg of n-propanol to curarized rabbits induced slow waves with high amplitude in EEG of the neo-cortex. In the hippocampal lead, there were two types of changes, one with persisting appearance of regular slow waves and the other with appearance of irregular slow waves. In the latter cases, the waves were accompanied with synchronization in the cortical lead. Change of EEG was similar in the case of noncurarized, unanesthetized rabbits. The above-mentioned effects were quite similar to those observed after the administration of methanol or ethanol. 2. Carbon disulfide: The intravenous injection of 0.1-0.2ml/kg of carbon disulfide to curarized cats revealed an appearance of slow waves and a decrease of amplitude in the cortical tracing. According to the changes of frequency and voltage of the electrical activity and of time from the administration to the beginning of flattening, the EEG patterns after administration were classified into four types; (I) rapid decrease of amplitude of the electrical activity in the neo-cortex followed by flattening in each lead without delay, (II) some delay in the appearance of flattening, after the decrease of amplitude in the neo-cortex, (III) a transitory arousal pattern in the neo-cortex, the amygdaloid nucleus and the hippocampus just after the injection, then appearance of slow waves in the neo-cortex about five minutes after the injection, and finally flattening of EEG, and (IV) no particular change. These types were dependent on whether the intravenous injection had been performed quickly or slowly. Type I or II was seen in cases when animals were injected quickly. Type III or IV was seen in cases when injections were performed slowly. In curarized rabbits, injected intravenously with doses at 0.1-0.3ml/kg, the resulst were similar. In the case of intraperioneal injection, type III or IV was observed. 3. O-Phthalodinitrile: Oral administration of doses ranging from 50 to 300mg/kg revealed the appearance of the slow wave burst or the spike and wave complex in the electrical activity of the neo-cortex in both curarized and non-curarized rabbits. When slow wave burst or spike and wave complex was found in EEG, none of excitatory symptoms was observed in the behaviour of non-curarized, unanesthetized rabbits. Seizure discharge in EEG was observed in all the rabbits except a case which had been given a single dose at 50mg/kg. Seizure discharge in EEG of non-curarized animals was accompanied with motor seizures. It is thought to be possible to classify the action of chemicals on the electrical activities of the central nervous system according to the change of frequency, voltage and shape of waves. As far as the present investigation is concerned, changes of the electrical activities after the administration of chemicals were classified into three patterns, namely appearance of slow waves, flattening and appearance of spike waves. It appears that observation of changes of EEG after the administration of chemicals are useful for the classification of toxicity of chemicals and for the comparison of effective doses of them under a definite experimental condition as in the case of this study.