title: Odor-avoidance or odor-preference induced by amphetamine in the infant rat depending on the dose and testing modality.
abstract: By the second postnatal week of life infant rats can acquire taste avoidance induced by amphetamine. Psychostimulant drugs supports appetitive and aversive learning in adult rats. Their appetitive effects are more likely to become associated with contextual cues, while the aversive ones have been consistently found in taste aversion learning. To explain this paradox, it has been proposed that rats would avoid a taste that predicts a change in their homeostasis because this species cannot vomit. In this study we assessed the motivational properties of amphetamine in preweanling rats by means of an odor conditioning preparation, which enables the analysis of the hedonic value of the memory by means of a consumption test or in terms of locomotor approach to the odor. Results indicate that regardless of the amphetamine dose (1 or 5 mg/kg), when animals were evaluated in the intake test, subjects avoided the odor. However, the outcome in the locomotor avoidance test varied as a function of the amphetamine dose. Rats trained with the low dose (1 mg/kg) showed odor preference, while the highest amphetamine dose (5 mg/kg) induced odor avoidance. When LiCl was employed as an unconditioned stimulus (US), rats showed avoidance in the intake and locomotor activity tests. These data indicate that amphetamine, like other drugs of abuse, supports appetitive conditioning in preweanling rats. Interestingly, infant rats expressed conditioned odor avoidance or preference depending on the dose and testing modality. Results were discussed considering current theories of avoidance learning induced by rewarding drugs.
authors.affiliation: Instituto de Investigación Medica Mercedes y Martín Ferreyra, Argentina.
authors.forename: Damian A
authors.initials: DA
authors.lastname: Revillo
authors.forename: Guillermo
authors.initials: G
authors.lastname: Fernandez
authors.forename: Stefania
authors.initials: S
authors.lastname: Castello
authors.forename: Maria Gabriela
authors.initials: MG
authors.lastname: Paglini
authors.forename: Carlos
authors.initials: C
authors.lastname: Arias
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn; D001245:Association Learning / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D008568:Memory / Q000187:drug effects; D009043:Motor Activity / Q000187:drug effects; D009812:Odorants; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000697:Central Nervous System Stimulants; D000661:Amphetamine