Evidence of melatonin involvement in pindolol-induced suppression of REM sleep

The effects of pindolol, melatonin, and the melatonin receptor agonist agomelatine were studied in rats implanted for chronic sleep procedures. Administration of pindolol (1.0-4.0 mg/kg) during the light phase induced a significant reduction of rapid-eye-movement sleep (REMS) and an increase of waking (W). In the rats recorded after receiving 1.0-6.0 mg/kg melatonin no significant differences were found in sleep or W compared with controls. Agomelatine (1.0-6.0 mg/kg) induced a significant increase of light sleep during the first 3 h of the recording period. Pretreatment with melatonin partly prevented the pindolol-induced suppression of REMS. However, agomelatine was ineffective in this respect. Overall, these data suggest that the decreased production of melatonin could play a role in REMS suppression related to pindolol administration.