The effects of infusions of CART 55-102 into the basolateral amygdala on amphetamine-induced conditioned place preference in rats.

RATIONALE: The affective aspects of D: -amphetamine (AMPH) may be mediated, in part, by cocaine- and amphetamine-regulated transcript (CART) peptides in the basolateral amygdala (BLA). The formation of context-drug associations produces either conditioned place preference (CPP) or conditioned place aversion (CPA). OBJECTIVES: The aim of the present study was to determine whether intra-BLA infusions of CART 55-102 are either rewarding or aversive and modulate AMPH reward. MATERIALS AND METHODS: Rats were implanted with bilateral cannulae in the BLA, were subjected to place conditioning, and were tested for CPP or CPA. Rats were conditioned with either intra-BLA infusions of artificial cerebral spinal fluid or one of three dose of CART 55-102 (1, 2, or 4 microg/side), intra-BLA infusions of a subrewarding dose of CART 55-102 (1 microg/side) plus injections of a subrewarding dose of AMPH (0.1 mg/kg, i.p.), or intra-BLA infusions of an aversive dose of CART 55-102 (4 microg/side) plus injections of a rewarding dose of AMPH (1.0 mg/kg, i.p.). RESULTS: Intra-BLA infusions of 2 microg/side CART 55-102 produced CPP, 4 microg/side produced CPA, and 1 microg/side produced neither CPP nor CPA. Intra-BLA infusions of a subrewarding dose of CART 55-102 (1 microg/side) plus injections of a subrewarding dose of AMPH (0.1 mg/kg, i.p.) produced CPP. Intra-BLA infusions of an aversive dose of CART 55-102 (4 microg/side) plus injections of a rewarding dose of AMPH (1.0 mg/kg, i.p.) produced neither CPP nor CPA. CONCLUSIONS: Both the affective properties of intra-BLA CART 55-102 and its ability to either facilitate or block AMPH reward are dose dependent.