Chronic lithium prevents REM sleep deprivation-induced increased responsiveness to apomorphine

REM sleep deprivation of rats induces an increased responsiveness to dopaminergic agonists. Chronic lithium (Li) has been reported to prevent the development of dopamine receptor supersensitivity induced by other agents. The effects of chronic dietary Li administration (producing a mean serum level of 0.96 mequiv. litre-1) and 96 h REM sleep deprivation were studied. Chronic Li completely blocked the increased stereotypy, and partially prevented the aggressive behaviour induced, respectively, by 0.6 and 5 mg kg-1 of apomorphine in REM sleep deprived rats compared with the appropriate control groups. This study constitutes the first attempt to evaluate chronic lithium effects on rats undergoing REM sleep deprivation, chosen as another method of inducing alteration of dopaminergic sensitivity.