Effect of beta-casomorphin on neonatal sleep in rats

Peptides. 1990 Jan-Feb;11(1):1-4. doi: 10.1016/0196-9781(90)90101-a.


The effects of bovine beta-casomorphin(1-7) (Tyr-Pro-Phe-Pro-Gly-Pro-Ile) on neonatal sleep in rats were studied. The pups received intraperitoneal injections of beta-casomorphin(1-7) (1 mg, 5 mg, 10 mg, 50 mg, or 100 mg/kg) or a corresponding volume of sodium chloride. In any of the doses used, beta-casomorphin(1-7) had no effect on waking. Only 100 mg/kg caused significant changes in sleep: the percentage of quiet state of the total recording time (TRT) increased and the percentage of active sleep decreased. Beta-casomorphin(1-7) did not cause significant respiratory depression. Naloxone pretreatment (1 mg/kg IP) reversed the effects of beta-casomorphin(1-7) on sleep, a finding which suggests that opiate mu-receptors are involved in mediating the sleep effects of beta-casomorphin.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Newborn / physiology*
  • Caseins / antagonists & inhibitors
  • Caseins / pharmacology*
  • Endorphins / antagonists & inhibitors
  • Endorphins / pharmacology*
  • Male
  • Molecular Sequence Data
  • Movement / drug effects
  • Naloxone / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Respiration / drug effects
  • Sleep / drug effects*
  • Wakefulness / drug effects


  • Caseins
  • Endorphins
  • Naloxone
  • beta-casomorphins