title: Age-dependent differences in morphine-induced taste aversions.
abstract: Adolescence is a developmental period of particular importance given the host of neurobiological changes that occur during this stage of development. Drug use and abuse is said to be a function of the balance of its rewarding and aversive effects, and any age-dependent differences in morphine's aversive effects could impact drug intake. The present experiments examined the ability of morphine sulfate (0, 3.2, 10, and 18 mg/kg) to induce taste aversions in adolescent and adult rats under high (20-min fluid access each day; Experiment 1A/B) and low (50% of ad libitum access; Experiment 2A/B) deprivation conditions. In both studies, adolescent and adult rats were given a novel saccharin solution to drink and were subsequently injected with morphine. Independent of the deprivation condition, adults acquired stronger aversions than adolescents and did so at a faster rate. On a subsequent two-bottle aversion test, all morphine-injected subjects drank a significantly lower percentage of saccharin than vehicle-injected controls with adults exhibiting stronger aversions than adolescents. These age-dependent differences in morphine-induced CTAs extend the findings with other drugs of abuse for which adolescents exhibit weaker aversions. The possible basis for and implications of these differences were discussed.
authors.affiliation: Psychopharmacology Laboratory, Department of Psychology, American University, 4400 Mass. Ave., NW, Washington, DC 20016,USA. zh7104a@american.edu
authors.forename: Zachary E
authors.initials: ZE
authors.lastname: Hurwitz
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Merluzzi
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Riley
mesh_terms: D000367:Age Factors; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003214:Conditioning, Classical / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012439:Saccharin; D013549:Sweetening Agents; D013649:Taste / Q000187:drug effects*; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D013549:Sweetening Agents; D009020:Morphine; D012439:Saccharin