Abstract
Effects of TRH on the central nervous system activity were investigated electrophysiologically. TRH (0.05-1.0mg/kg) was injected intravenously in the rabbit and the following were observed.
1. The threshold of arousal reaction of the cerebral cortex EEG and hippocampus EEG and those of evoked muscular discharges in the fore and hind limbs due to 100Hz stimulation of the brain stem reticular formation decreased after administration of TRH.
2. These decreases persisted a considerably long time (at least on e hour).
3. The threshold of the evoked muscular discharges in the fore and hind limbs due to stimulation of the cerebral cortex decreased after administration of TRH.
4. The threshold of the evoked muscular discharges in the for e and hind limbs due to stimulation of the hippocampus increased after administration of TRH. It was suggested that the TRH has consciousness-arousing act ivity, a facilitatory effect on the pyramidal system and an inhibitory effect on the extrapyramidal system.
