Mianserin hydrochlorideおよびSodium valproateの聴覚性誘発電位 (AEP)および脳波への急性効果

The acute effects of mianserin hydrochloride (MSR) and sodium valproate (VPA) were studied by auditory evoked potential (AEP), with 16 healthy male subjects (26~43 y. o.). In the two experimental session on different days, MSR (0.3 mg/kg) or VPA (5 mg/ kg) were orally administered for each subjects. EEGs containing AEPs evoked by click stimuli once every 5 sec were derived from the two derivations (3 ch : Cz→A1+2, 6 ch : Cz →T 5 ) and recorded into magnetic tape. Reproducing the tape, AEPs with 1024 msec of analysis time were obtained by averaging 100 responses, and EEGs were subjected to the frequency analysis. In the experimental session, EEG containing AEPs were recorded befored and 60, 120, and 180 min after the administration of MSR, and before and 30, 60, and 90 min after VPA. Consecutive changes of group mean AEP were studied. Individual AEPs were subjected to the component analysis, and to the statistical assessment together with EEG. The followig results were obtained.
1. After the administration of MSR, P2 and P3 latenies of the middle latency components and those of long latency components (P6~) of AEP significantly increased. All of significant changes were decrease for the peak-to-peak amplitudes of the AEP components. These inhibitory effects of MSR on AEP were attributed to the antihistaminergic effect of MSR. Moreover, significant positive correlation was found between δ and θ power % of EEG and P2 and P3 latencies, significant negative correlation between α2 and β2 power % of EEG and P2 latency, and between α2 power % of EEG and P3 latency. These results indicate that not only P2 but also P3 reflect the activities of the reticular formation and thalamocortical systems.
2. After the administration of VPA, latencies of long latency components (P6~) significantly increased, but those of middle latency components (Pl~P3) did not significantly change. These results were attributed to the inhibitory effects of VPA on the cerebral cortex through GABA neuron system.
3. From these results, it was considered that MSR has more inhibitory effect on the reticular formation and thalamocortical systems, and VPA has main inhibitory effect on the cerebral cortex.