Similar effect on REM sleep but differential effect on slow wave sleep of the two 5-HT uptake inhibitors zimeldine and alaproclate in cats and rats

Abstract

Sleep and waking in cats and rats were studied 6–10 hours following acute administration of zimeldine, alaproclate or saline. The effects on slow wave sleep of the two compounds markedly differed in the cats. Following zimeldine, sleep with a high amount of synchronized slow waves (SWS-2) was increased, and total sleep was unchanged. Following alaproclate, SWS-2 did not increase, and total sleep was reduced. In the rats, zimeldine increased SWS-2 during the first 4 hours after administration, while there was no change in SWS following alaproclate. Both zimeldine and alaproclate increased REM latency and reduced REM sleep in both species with somewhat more pronounced effects in cats than in rats. The results on SWS-2 following zimeldine are consistent with earlier results following serotonin depletion in both species. The differential effects on SWS-2 are discussed in terms of regional differences in uptake inhibition and other differences between the two uptake inhibitors. The results on REM sleep confirm earlier results involving serotonin uptake inhibitors and serotonin precursor loading and indicate that increased synaptic serotonin concentrations suppress REM sleep.