David Cannon

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delta-Opioid receptors have been implicated in reinforcement processes and antagonists are available that produce long-lasting and selective antagonism of delta-opioid receptors in vivo. This experiment assessed the contribution of delta-opioid receptors to the antinociceptive and reinforcing properties of heroin. The effects of the irreversible(More)
Several self-administration models have been used to study the interactions between cocaine and heroin, and the schedule of reinforcement used is an important consideration for these studies. Behavior maintained by cocaine, heroin or their combination was studied using a discrete trial schedule that has been described for cocaine self-administration(More)
Lever pressing in rats (N=5) was reinforced under a progressive-ratio (PR) schedule of food presentation, in which the number of responses required increased exponentially. The session was terminated when 1 h passed without completion of the scheduled ratio. Doses of cocaine (5.6-42.0 mg/kg; one subject received a dose of 56.0 mg/kg) as well as saline were(More)
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