The effect of some psychotropic drugs on the electric activity of the brain and sleep cycle pattern of the cat.

Abstract

Summary1) The effects of chronic administration of psychotropic drugs such as imipramine, atropine sulfate, chlorpromazine, perphenazine, levomepromazine, pentobarbital sodium, chlordiazepoxide, neostigmine and reserpine on the electric activity of the brain and sleep cycle pattern were investigated using adult cats carrying chronically implanted electrodes.2) Modification of sleep cycle pattern by chronic administration of the psycho‐tropic drugs was classified into 5 types (Type I, II, III, IV, V).3) Chronic administration of 7 mg/kg/day of imipramine increased the slow activity in the neocortical and limbic structures and also enhanced the fast activity in the amygdaloid nucleus. It also suppressed the occurrence of the activated sleep (S‐A) period almost completely (S‐A suppressing effect) and increased the amount of spindle and slow wave stage (S‐2 stage) (Type‐V modification). The amount of S‐A stage increased transiently at the time of discontinuation of the drug.4) Atropine sulfate, 3 mg/kg/day, has the effects on both the electric activity of the brain and sleep cycle pattern similar to those of imipramine (Type‐V), though it was slightly weaker at this dosage.5) Chlorpromazine 4 mg/kg/day caused both synchronization of the neocortical activity and increase in the total amount of sleep particularly that of S‐2 stage without significant change in the amount of S‐A stage (Type‐II). The same drug, 7 mg/kg/day, enhanced the fast activity and spikes in the amygdala and hippocampus. The medication increased the amount of A and S‐1 stages and decreased those of S‐2 and S‐A stages (Type‐III).6) Perphenazine, 1.3 mg/kg/day, and levomepromazine, I mg/kg/day, increased the amount of S‐1 and S‐2 stages but they also had a slight S‐A suppressing effect (Type‐IV).7) Chronic administration of 13 mg/kg/day of pentobarbital sodium increased total amount of sleep particularly those of S‐1 and S‐2 stages with a slight suppression of S‐A stage (Type‐I). A temporary reduction of the amount of sleep was observed at the time of discontinuation of the drug. The effect of 3 mg/kg/day of chlordiazepoxide on sleep cycle pattern was similar to that of pentobarbital (Type‐I), though it was less remarkable than the latter.8) Neostigmine, 0.3 mg/kg/day, caused a reduction in the amount of S‐2 and S‐A stages and increased those of A and S‐1 stages (Type‐III). No increase in the amount of S‐A stage was observed. Reserpine, 1.5 mg/kg/day, also caused a remarkable suppression of S‐2 and S‐A stages during the period of medication (Type‐III).9) The mode of action of these psychotropic drugs was discussed.