Preferred tastes and opioid-modulated behaviors in neonatal rats.
Ten-day-old rats were given various tastants to ingest, independent of mother and suckling. Relative to water, the pups ingested significantly more saccharin (0.5%) and NaCl (2.5%) and less quinine (0.4%). Pretreatment with the opiate antagonist, naltrexone, had no effect on water or quinine intake but significantly reduced that of saccharin and NaCl. Furthermore, the preferred solutions of saccharin and NaCl given intraorally caused a decrease in ultrasonic vocalizations of isolated pups and in a separate experiment caused an analgesic response to heat. Both phenomena were reversible with naltrexone administration, suggesting that preferred tastes elicit an endogenous opioid response significantly affecting behaviors seen during isolation.
Kehoe
P
P
Department of Psychology, Trinity College, Hartford, CT 06106.
Sakurai
S
S
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology; D001921:Brain / Q000502:physiology; D004723:Endorphins / Q000502:physiology*; D005518:Food Preferences / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000502:physiology*; D013649:Taste / Q000502:physiology*; D013652:Taste Threshold / Q000502:physiology
D004723:Endorphins; D011957:Receptors, Opioid