The effects of zimeldine and alaproclate combined with a small dose of 5-HTP on waking and sleep stages in cats.

Sleep and waking stages in cats were studied 8 h following administration of zimeldine and alaproclate, in combination with saline or 5-hydroxy-1-tryptophan (5-HTP). Both drugs in combination with saline reduced rapid eye movement sleep and ponto-geniculo-occipital wave activity, and the effects were potentiated with 5-HTP. After administration of zimeldine in combination with 5-HTP there was an increase in synchronized waking (W-2), followed by an increase in slow wave sleep (SWS), at first SWS-1 with spindles and then highly synchronized SWS-2. The changes were interpreted as reflecting a serotonergic deactivating effect expressed by an electroencephalographic synchronizing effect. This is consistent with earlier studies following serotonin depletion and serotonin precursor loading. After alaproclate in combination with 5-HTP there were changes in W-2 and SWS-1 suggestive of the same process but much less pronounced. The difference between the two serotonin uptake inhibitors is interpreted as being due to regional differences in their uptake inhibition.