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: Reinforcing properties of stereoisomers of the putative sigma agonists N-allylnormetazocine and cyclazocine in rhesus monkeys.
    Author: Slifer BL, Balster RL.
    Journal: J Pharmacol Exp Ther; 1983 Jun; 225(3):522-8. PubMed ID: 6306209.
    Abstract:
    There are many similarities in the effects of phencyclidine (PCP) and opioids with sigma agonist activity such as N-allylnormetazocine (SKF-10,047) and cyclazocine. Yet PCP and sigma agonists differ in reinforcing properties. PCP is reliably self-administered in animal models and has abuse liability in humans, whereas (+/-)-N-allylnormetazocine and (+/-)-cyclazocine are not self-administered or abused. Inasmuch as other research has demonstrated differences in the selectivity of PCP-like effects of the stereoisomers of opioids, this study compared the reinforcing properties of PCP to the reinforcing properties of isomers of N-allylnormetazocine and cyclazocine. Rhesus monkeys were trained to lever-press on a fixed-ratio 10 schedule for i.v. cocaine (50 micrograms/kg/injection). During substitution tests, cocaine was replaced with various doses of test drugs or vehicle. The drugs tested were PCP, (+/-)-N-allylnormetazocine, (-)-N-allylnormetazocine, (+)-N-allylnormetazocine, (+/-)-cyclazocine, (-)-cyclazocine and (+)-cyclazocine. PCP and the (+)-isomers of both benzomorphans, at one or more doses, were self-administered at rates which exceeded rates maintained by vehicle and which equaled or exceeded cocaine-maintained base-line rates. Neither the racemates nor the (-)-isomers of N-allylnormetazocine or cyclazocine were self-administered by the monkeys at rates which were greater than vehicle control levels of responding. Reinforcing doses of the three compounds resulted in injections evenly distributed across the 60-min session in a pattern similar to cocaine self-administration, whereas the racemic mixtures and the (-)-isomers produced negatively accelerated patterns of injections which resembled typical saline patterns of extinction responding. These data provide further evidence that the (+)-isomers of sigma agonists are more selective for PCP-like effects than the (-)-isomers in monkeys.
    [Abstract] [Full Text] [Related] [New Search]