Persistent elevation of nocturnal activity in rodents following apparent recovery from lithium/pilocarpine-induced limbic seizures.

The nocturnal and day-time activity of rats was monitored continuously after the induction of seizures by a single systemic injection of lithium followed 4 hr. later by the muscarinic agent pilocarpine. Although there was a transient increase in activity during the day cycle shortly after the seizure induction, this behavior returned to baseline levels; however, nocturnal activity increased and remained elevated two or three times above the baseline levels. Implications for the enhancement of nocturnal melatonin levels within the brains of these chronically epileptic rats are discussed.