alpha-Flupenthixol increases slow-wave in rats: effect of dopamine receptor blockade.

alpha-Flupenthixol (0.2 mg/kg, i.p.), a dopamine receptor blocker, significantly increased slow-wave sleep and decreased wakefulness in rats when administered either at the onset of a 12-hr light period or a 12-hr dark period. The same dose of the drug strongly antagonized the dopamine-mediated stereotype produced by an injection of apomorphine (1 mg/kg, i.p.) for at least 9-hr, indicating that dopamine receptors were blocked throughout most of the recording session. The results suggest a relationship between the blockade of dopamine receptors and the increase of slow-wave sleep time.