Mianserin hydrochlorideおよびsodium valproateの視覚誘発電位(VEP)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 visual evoked potential (VEP), 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 VEPs evoked by flash stimuli once every 5 sec were derived from the two derivations (2ch : 01→A1+2, 5ch : 01→Cz) and recorded into magnetic tape. Reproducing the tape, VEPs with 1024 msec of analysis time were obtained by averaging 100 responses, and EEGs were subjected to the frequency ayalysis. In the experimental session, EEG containing VEPs were recorded before and 60, 120, and 180 min after the administration of MSR, and before and 30, 60, and 90 min after VPA. Consecutive change of group mean VEP were studied. Individual VEPs were subjected to the component analysis, and to the statistical assessment together with EEG.
The following results were obtained.
1. After the administration of MSR, P3 and N3 latencies of the short latency components of VEP significantly increased. And most of those of long latency components (N6~) significantly increased. The peak-to-peak amplitude P3-N3 and N3-P4 significantly decreased. In EEG, the power % of δ, θ and β2 frequency band increased, and that of α2 decreased. Significant positive correlation was found between δ and θ power % of EEG and latencies and amplitudes of VEP, and significant negative correlation was found between α2 and β2 power % and latencies and amplitudes. These findings indicate the inhibitory effect of MSR mainly on the lateral geniculate body and the optic radiation in the visual system.
2. After the administration of VPA, latencies of the long latency components (P7~) of VEP sigificantly increased, but those of short latency components did not change significantly. The peak-to-peak amplitudes inconsistently decreased mainly in the short latency components. In EEG, the power % of θ frequency band increased and that of β2 decreased. Significant positive correlation was found between δ and θ power % of EEG and latencies of VEP mainly in the long latency components (P7~), and significant negative correlation was found between δ and θ power % of EEG and amplitudes of VEP mainly in the long latency components (P6~). These findings indicate the inhibitory effect of VPA mainly on the cerebral cortex through GABA neuron system.