Foltin RW, Evans SM. Hypocretin/orexin antagonists decrease cocaine self-administration by female rhesus monkeys.
Drug Alcohol Depend 2018;
188:318-327. [PMID:
29852449 PMCID:
PMC7059601 DOI:
10.1016/j.drugalcdep.2018.04.018]
[Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/10/2018] [Accepted: 04/10/2018] [Indexed: 01/02/2023]
Abstract
BACKGROUND
The hypocretin/orexin system is involved in regulating arousal, and much recent work demonstrates that decreasing hypocretin receptor-1 (HCRTr1) activity using antagonists decreases appetitive behavior, including stimulant drug self-administration and reinstatement.
METHODS
The present study determined the effects of hypocretin-1 and HCRTr1 antagonists on responding reinforced by intravenous (i.v.) cocaine self-administration (0.0125 - 0.05 mg/kg/infusion) in 5 female rhesus monkeys. Responding was examined using 3 schedules of reinforcement: 1) a Fixed interval 1 min, Fixed ratio 10 Chain schedule [FI 1-min (FR10:S)], 2) a Progressive Ratio (PR) schedule, and 3) a cocaine vs. candy.
RESULTS
Choice schedule: the HCRTr1 antagonist SB-334867 (8-24 mg/kg, i.m.) decreased cocaine taking under the Chain schedule and PR schedule in all 5 monkeys and in 4 of the 5 monkeys under the Choice schedule. d- Amphetamine (0.06 - 0.25 mg/kg, i.m.), tested as a control manipulation, decreased cocaine taking in all 5 monkeys under the Chain schedule. The peptide hypocretin-1 (0.072 mg/kg, i.v.) increased cocaine taking in the monkeys with low rates of cocaine taking under the Chain (3/4) and Choice (4/5) schedules. Reinstatement of extinguished cocaine responding following response-independent delivery of a large dose of cocaine (0.3 mg/kg) was attenuated in 3 of the 5 monkeys by the HCRTr1 antagonist SB-334867.
CONCLUSIONS
These data expand upon work accomplished in predominantly male rodents suggesting that the hypocretin system modulates the response to appetitive stimuli. A better understanding of this system offers promise as a novel approach in medication development for appetitive disorders.
Collapse