Milk-induced analgesia and comforting in 10-day-old rats: opioid mediation.
The effects of slow intraoral milk infusions on the opioid-mediated behaviors of ultrasonic vocalizations and paw removal from a hot plate (48-49 degrees C) were evaluated in 10-day-old rats. Milk reduced distress vocalization by circa 30% while increasing paw lift latencies by about 60%. Alterations in both behaviors were fully reversed by naltrexone (0.5 mg/kg) pretreatments. These data demonstrate the calming and analgesic effects of milk. Implications for a possible role of opioid peptides in mother-young relationships are discussed.
Blass
E M
EM
Department of Psychology, Johns Hopkins University, Baltimore, MD 21218.
Fitzgerald
E
E
D000161:Acoustic Stimulation; D000698:Analgesia; D000818:Animals; D005260:Female; D008892:Milk; D009271:Naltrexone / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000502:physiology*; D014465:Ultrasonics; D014828:Vocalization, Animal / Q000187:drug effects
D011957:Receptors, Opioid; D009271:Naltrexone