Delta/mu opioid receptor interactions in operant conditioning assays of pain-depressed responding and drug-induced rate suppression: assessment of therapeutic index in male Sprague Dawley rats

Rationale and objectives Although delta/mu receptor interactions vary as a function of behavioral endpoint, there have been no assessments of these interactions using assays of pain-depressed responding. This is the first report of delta/mu interactions using an assay of pain-depressed behavior.