抄録
Rabbits were put into a special box which had a gas-exit and an upperpositioned gas-inlet, from which the Japanese Industrial Standard No. 3 Liquefied Petroleum Gas (L. P. G.) was distributed on equal proportion. The changes in the behavior were noted as follows: Initially, licking and sniffing appeared, and at about one hour later when the L. P. G. concentration reached approximately 30%, the walking got difficult, and occasional screaming were heard as the sign of stimulation. At about 100 minutes later, namely at approximately 60% L.P.G. concentration, temporary nystagmus appeared. After that, the muscles were hypotonic, and an excessive salivation was noted. The E. C. G. changes were as follows: With the initial sending in of L. P. G., the pulse rate increased gradually until about the 2 hours' peak-point after which it decreased again being accompanied with S-T depression and inverted T wave, clearly indicating the presence of some cardiac damage. The neocortex showed a gradual change into a drowsy pattern, while the hippocampus and amygdala showed a marked arousal pattern. Especially the amygdala evoked many preseizure and seizure-spikes, and other amygdala-related locations like the anterior hypothalamus showed a similar tendency. At 2 hours of experiment, both the activation effect of the reticular formation over the neocortex and the recruiting response of N. centrum medianum of thalamus showed a marked elevation of threshold. At this stage, the seizure discharge due to the electric stimulation of hippocampus or amygdala showed only a slight decrease of amplitude but the duration remained almost unchanged.
