The action of lithium carbonate on the sleep-waking cycle in the cat

The therapeutic effect of lithium carbonate on manic-depressive psychosis is now universally recognized. In view of this positive action on the cyclic endogenous manifestations, it was interesting to investigate the possible effects of lithium on the sleep-waking cycle in the cat. Polygraphic recording from three adults cats was carried out during 24 h periods before, and on different days after, beginning treatment with lithium carbonate. With low doses (30 and 50 mg/kg/day), important morphological changes were observed 5 days later while a new balance of the sleep-waking stages occurred. The EEG of each stage was characterized by slowing and amplitude increase of the different frequencies. The rhythms which appeared in long runs during quiet wakefulness and paradoxical sleep (PS) in the somaethetic cortex (mu rhythm) and the visual areas (alpha rhythm) were increased, slowed and almost continuously present. From the quantitative point of view, the percentage of time of deep slow wave sleep (DSWS) was increased from 38% to 55%. Conversely, the waking and PS times were both reduced, the latter from 18% to 10%. In contrast with human data, the mean duration of PS episodes was unchanged. Furthermore, lithium induced a slight dissociation between EEG activity and waking behaviour. With toxic dose (90 mg/kg/day) all the above changes were again observed, but more conspicuously. During wakefulness and SWS, bursts of generalized paroxysmal events appeared, in frequent association with a myoclonic jerk. SP became atypical and its percentage of time was drastically reduced.