Chronic zimeldine administration to cats: sustained increase of serotonergic effect as measured with sleep parameters.

Sleep effects of oral administration of the serotonin uptake inhibitor zimeldine to cats on 15 consecutive days was measured. On administration days 8 and 15 REM sleep and PGO activity were significantly reduced. The amount of SWS-2 was not changed for the whole group, but a subgroup with low baseline values showed an increase during zimeldine administration. A REM sleep rebound was observed on withdrawal day 2, and NREM sleep PGO activity was increased on withdrawal day 5. The results indicate an increased serotonergic inhibition of PGO wave activity and REM sleep during chronic administration of zimeldine.