Electroencephalographic study on the central action of a new anxiolytic: 3a alpha, 4 beta, 7 beta, 7a alpha-hexahydro-2- (4- (4- (2-pyrimidinyl) -1- piperazinyl) -butyl) -4, 7-methano-1H-isoindole-1, 3 (2H) -dione dihydrogen citrate (SM-3997)
Hirose, A.; Sasa, M.; Akaike, A.; Takaori, S.
Nihon Yakurigaku Zasshi. Folia Pharmacologica Japonica 93(2): 41-47
1989
ISSN/ISBN: 0015-5691 PMID: 2566565 Document Number: 340180
Electroencephalographic (EEG) studies were performed to examine the effects of SM-3997 on the spontaneous EEG, EEG arousal responses, recruiting responses and hippocampal afterdischarges in rabbits and the spontaneous EEG in chronically electrode-implanted rats. In acute experiments using rabbits, SM-3997 at doses of 1 .apprx. 8 mg/kg, i.v., produced low-voltage fast waves in cortical EEG and slow waves with reduction of the ampitude in hippocampal EEG. The drug at doses of 1 .apprx. 3 mg/kg, i.v., dose-dependently inhibited the threshold stimulus voltages in EEG arousal responses by stimulation of the midbrain reticular formation and slightly inhibited the threshold in recruiting responses by stimulation of the centromedian nucleus of the thalamus. However, the cortical and hippocampal afterdischarges inducd by hippocampal stimulation remained unaffected by SM-3997 at doses up to 3 mg/kg, i.v., while they were inhibited by diazepam of 1 mg/kg, i.v. In the study using rats in which electrodes were chronically implaned, SM-3997 at doses of 10 .apprx. 30 mg/kg, i.p., also produced low voltage fast waves in cortical EEG and slow waves of reduced amplitude in hippocampal EEG; and it simultaneously caused flat body posture. These results suggest that SM-3997 acts on both the cerebral cortex and hippocampus, inducing much more pronounced inhibition on the midbrain reticular formation-hippocampal system.