Persistent increase in the motivation to take heroin
in rats with a history of drug escalation
by
Ahmed SH, Walker JR, Koob GF
Division of Psychopharmacology,
Department of Neuropharmacology,
The Scripps Research Institute,
La Jolla, CA, USA.
Neuropsychopharmacology 2000 Apr; 22(4):413-21

ABSTRACT

The transition from stable to escalated levels of cocaine self-administration has been shown to depend upon drug availability. The generality of this phenomenon is assessed here by studying the effects of availability on heroin self-administration. Two groups of rats were trained on a 1-h continuous schedule of self-administration, after which, access to heroin (40 mg/injection) was increased to 11 h in one group (long access or LgA rats) or kept to 1 h in the other group (short access or ShA rats). After 18 sessions on this regimen, both ShA and LgA rats were tested for extinction and stress-induced reinstatement of heroin-seeking behavior. In LgA rats, both total and first hour intake gradually escalated over time. After escalation, LgA rats were slower to extinguish heroin-seeking behavior and responded more to the reinstating effect of stress after extinction. These findings show that: (1) the escalation process in drug consumption is common to both opiate and stimulant self-administration; (2) escalation in heroin consumption is associated with a persistent increase in the motivation for taking heroin.

Heroin Inc
Speedballs
Dutch heroin
Self-medication
Heroin in Vienna
Monkeys on heroin
Intravenous heroin
Heroin and nitric oxide
Heroin versus morphine
The extended amygdala
Heroin, GABAA and the NAcc
Baclofen, dopamine and heroin
Dosage, route of administration and withdrawal

Refs
HOME
HedWeb
cannabis-marijuana.com
BLTC Research
Paradise-Engineering
The Hedonistic Imperative
When Is It Best to Take Crack Cocaine?