Ultrasonic vocalization in rat pups as a marker of behavioral development: an investigation of the effects of drugs influencing brain opioid system.
Early postnatal exposure to morphine significantly influenced the ultrasonic vocalization of rat pups removed from their nest. In particular, a significant decrease in the rate of calling, sound pressure level and range of frequency was found in morphine-treated animals; moreover, the duration of calls was significantly increased by morphine administration. Conversely, neither beta-casomorphins (beta CMS), which are opioid peptides derived from the enzymatic digestion of milk protein (beta-casein), nor an opioid antagonist, like naloxone, significantly affected ultrasonic emission. The results are discussed with particular reference to the role of the opioid system in separation distress-induced vocalization in young animals.
Cuomo
V
V
Institute of Pharmacology, University of Bari, Italy.
Cagiano
R
R
De Salvia
M A
MA
Restani
P
P
Galimberti
R
R
Colonna
S
S
Racagni
G
G
Galli
C L
CL
D000375:Aging / Q000523:psychology*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002364:Caseins; D004723:Endorphins / Q000494:pharmacology*; D005260:Female; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D014465:Ultrasonics; D014828:Vocalization, Animal / Q000187:drug effects*
D002364:Caseins; D004723:Endorphins; D009270:Naloxone; D009020:Morphine; C021968:beta-casomorphins