Actigraphy-based sleep parameters during the reinstatement of methamphetamine self-administration in rhesus monkeys.

• Type of Material: Article
• Authors: Laís F. Berro, Emory University; Monica L. Andersen, Universidade Federal de São Paulo; Sergio Tufik Tufik, Universidade Federal de São Paulo; Leonard Howell, Emory University
• Language: English
• Date: 2016
• Publisher: American Psychological Association
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: 'This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.'
• Final Published Version (URL): http://dx.doi.org/10.1037/pha0000064
• Title of Journal or Parent Work: Experimental and Clinical Psychopharmacology
• ISSN: 1064-1297
• Volume: 24
• Issue: 2
• Start Page: 142
• End Page: 146
• Keywords: methamphetamine; rhesus monkeys; reinstatement; self-administration; nighttime activity
• Research Categories: Psychology, Psychobiology; Biology, Neuroscience

Abstract

The objective of the present study was to investigate nighttime activity of nonhuman primates during extinction and cue- and drug-primed reinstatement of methamphetamine self-administration. Adult rhesus monkeys (Macaca mulatta; n = 5) self-administered methamphetamine (0.01 mg/kg/injection, i.v.) under a fixed-ratio 20 schedule of reinforcement. Saline infusions were then substituted for methamphetamine and stimulus light (drug-conditioned stimulus presented during drug self-administration) withheld until subjects reached extinction criteria. Drug- and cue-induced reinstatement effects were evaluated after i.v. non-contingent priming injections of methamphetamine (0.03, 0.1 or 0.3 mg/kg). Activity-based sleep measures were evaluated with Actiwatch monitors a week before (baseline nighttime activity parameters) and throughout the protocol. Although methamphetamine self-administration did not significantly affect nighttime activity compared to baseline, sleep-like parameters were improved during extinction compared to self-administration maintenance. Priming injection of 0.1 mg/kg methamphetamine, but not 0.03 or 0.3 mg/kg, induced significant reinstatement effects. These behavioral responses were accompanied by nighttime outcomes, with increased sleep fragmentation and decreased sleep efficiency in the night following 0.1 mg/kg methamphetamine-induced reinstatement. In the absence of both drug and drug-paired cues (extinction conditions), nighttime activity decreased compared to self-administration maintenance. Additionally, effective reinstatement conditions impaired sleep-like measures. Our data indicate that the reintroduction of the stimulus light as a drug-paired cue increased nighttime activity.