Abstract

Speed of drug onset is assumed to be an important determinant of the abuse liability of a drug. Studies in human and non-human primates suggest that the subjective and reinforcing effects of cocaine can be influenced by route of administration and/or speed of intravenous injection. Sensitization to the reinforcing effects of cocaine was studied in rats and the effects of various injection durations (i.e. speed of injection) on the development of sensitization was examined using a progressive ratio schedule. In addition, the effects of cocaine dose on sensitization and the effects of injection duration on the acute reinforcing effects of cocaine were examined. The initial study demonstrated that the development of sensitization (i.e. progressive increases in breakpoints) was dose-dependent. A robust sensitization of the reinforcing effects of cocaine was replicated in animals receiving cocaine at the highest rate (i.e. shortest duration; 5 s), but not in animals receiving the same dose over 25 or 50 s. Subsequent testing revealed that injection duration did not have profound effects on the acute reinforcing effects of cocaine (assessed by breakpoints or rate of responding on a fixed ratio schedule). These findings are similar to recent studies demonstrating that the development of sensitization, but not the acute responsivity, to cocaine's locomotor-activating effects are influenced by rate of intravenous injection. Taking these findings together, we hypothesize that the process of drug addiction involves both the acute reinforcing effects and the development of sensitization.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.