Electrophysiological changes induced by paradoxical sleep deprivation and lithium chloride poisoning in rats

In an attempt to analyze the disruption of conditioned taste aversion (CTA) caused by pre-acquisition paradoxical sleep deprivation (PSD), the effect of poisoning (0.15 M LiCl, 4% body weight) on the sleep--wakefulness pattern was studied in 12 rats with chronically implanted electrodes. The polygraphic recording showed that poisoning reduced the total sleep time in the subsequent 3 h from 57 to 42% and REM sleep from 6 to 2%. The lithium chloride effect was still more pronounced after 24-h REM sleep deprivation: the total sleep time decreased from 67 to 46% and REM sleep from 13 to 2%. The change of sleep--wakefulness pattern, most pronounced during the first hour of poisoning, gradually returned to normal but REM sleep was significantly reduced even 3 h after poisoning. It is concluded that 24-h PSD does not alleviate the subsequent poisoning. On the other hand, the lithium chloride induced reduction of post-acquisition REM sleep many enhance the learning impairment caused by pre-acquisition PSD.