Inhibition of kappa opioid receptors attenuated increased cocaine intake in rats with extended access to cocaine.

ABSTRACT:

Objective

Previous studies demonstrated that the dynorphin/kappa opioid system was up-regulated upon repeated cocaine self-administration. In the present study, we tested the hypothesis that increased cocaine self-administration with extended access was associated with increased activity of the kappa opioid system in rats.

Materials and methods

Rats self-administered 0.5 mg/kg per injection of cocaine on a fixed-ratio (FR) schedule in either 1-h (short access, ShA) or 6-h (long access, LgA) sessions. After cocaine intake in the LgA rats increased to a maximum, the effects of kappa opioid receptor antagonists and a partial agonist were tested on cocaine intake in ShA and LgA rats.

Results

Cocaine self-administration increased under FR and progressive-ratio (PR) schedul

SUBMITTER: Wee S 

PROVIDER: S-EPMC2739447 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature