These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Diurnal patterns of cocaine and heroin self-administration in rhesus monkeys responding under a schedule of multiple daily sessions.
    Author: Negus SS, Mello NK, Lukas SE, Mendelson JH.
    Journal: Behav Pharmacol; 1995 Dec; 6(8):763-775. PubMed ID: 11224379.
    Abstract:
    A number of non-pharmacological factors have been shown to influence drug self-administration in experimental animals. This report examines diurnal changes in drug self-administration by rhesus monkeys trained to self-administer food (1gm fruit-flavored pellets) and cocaine (0.01 or 0.032mg/kg/injection) under a second order FR4 (VR16:S) schedule during four daily food and drug self-administration sessions. Saline, different unit doses of cocaine (0.001-0.1mg/kg/injection) or different unit doses of heroin (0.0001-0.01mg/kg/injection) were substituted for the maintenance dose of cocaine during drug sessions. Dose-effect curves relating unit dose of cocaine or heroin to the number of injections per session displayed an inverted U-shape during each of the four daily drug sessions. When 0.032mg/kg/injection cocaine or 0.0032mg/kg/injection heroin were available, monkeys usually self-administered the maximum number of injections during all four drug sessions. Substitution of saline or lower unit doses of cocaine (0.001-0.01mg/kg/injection) or heroin (0.0001-0.001mg/kg/injection) decreased the number of injections/session; however, these decreases were consistently greater during the evening (20.00-21.00h) and morning (07.00-08.00h) sessions than during the afternoon sessions (12.00-13.00h and 16.00-17.00h). As a result, the ascending limbs of the cocaine and heroin dose-effect curves for the evening and morning sessions were shifted to the right of the ascending limbs of the dose-effect curves for the afternoon sessions. Moreover, when saline was substituted for cocaine for only two sessions per day, drug self-administration decreased more during the evening and morning sessions even when the cocaine was available during those sessions. These findings suggest a diurnal variation in cocaine and heroin self-administration. Specifically, drug self-administration during the evening and morning sessions appears to be more sensitive to a decrease in reinforcer magnitude than responding during the afternoon sessions. These findings confirm and extend previous reports of the influence of non-pharmacological factors on drug self-administration.
    [Abstract] [Full Text] [Related] [New Search]