REPEATED REM-SLEEP DEPRIVATION AFTER CHRONIC HALOPERIDOL ADMINISTRATION IN THE RAT

Repeated haloperidol administration produces up-regulation of dopamine (DA) receptors. REM sleep deprivation (REMSD) does also, but in addit ion, has been shown to produce REM sleep rebound. Should DA receptor u p-regulation play a role in REM sleep rebound, haloperidol could conce ivably have effects similar to those observed following REMSD. This is the central question investigated in this study.: Male Wistar rats we re prepared for sleep recordings. They were randomly assigned to the f ollowing groups: group 1, REMSD by small platforms (40 h REMSD + 8 h r ecording); group 2, was the large platform control group (40 h in larg e platforms + 8 h of recording); group 3, received 2-week daily admini stration of haloperidol (3 mg/kg, IP) plus REMSD (40 h REMSD + 8 h of recording); group 1, 2-week administration of haloperidol(3 mg/kg) wit hout sleep manipulation and at the end 40 h were allowed to elapse, fo llowing which 8 h of sleep recordings was carried out. In each group t he sleep manipulation and/or sleep recordings were repeated five conse cutive times. Repeated REMSD produced increases of REM sleep time afte r each recovery in group 1. Large platforms did not produce increases of REM sleep during the recovery trials. The 2-week administration of haloperidol plus RER ?SD prevented REM sleep rebound (group 3). The 2- week administration of haloperidol without sleep manipulation (group 3 ) produced a REM sleep reduction. Dopamine modulation seems not to be important for REM sleep rebound. Hypersensitivity of DA receptors deve loped after REMSD may be an epiphenomenon associated with this sleep m anipulation, but seems not to participate in REM sleep enhancement aft er REMSD.