Affective states associated with morphine injections

Methods of deconditioning persisting avoidance: Drugs as adjuncts to response prevention

“…At both of these times after dosing, there is probably a positive affective state engendered (Rossi & Reid, 1976). Rats were treated at both of these times after subcutaneous injections.…”

Conditioned place preference: what does it add to our preclinical understanding of drug reward?

“…Importantly, Beach (1957) also found that the morphine-paired white arm was preferred to an unpaired black arm in non-dependent rats, indicating that the induction of physical dependence is not a prerequisite for obtaining CPP. Following this demonstration of CPP using a discrete trial choice procedure, Rossi and Reid (1976) published a report of morphine CPP in which the duration of time spent in a morphine-paired context relative to a saline-paired context was used as the index of preference. To date, the general procedure described by Rossi and Reid (1976) has been adopted for essentially all subsequent CPP studies, with some modifi cations.…”

Addictive agents and intracranial stimulation: Self-stimulation under morphine, amphetamine, and chlorpromazine

“…Such increased pressing is not a product of potential increased acitivity that might have occurred with this regimen of dosing and testing (Lorens & Mitchell, 1973), nor a product of morphine's analgesic properties (Farber & Reid, 1976). Increased pressing seems to parallel a positive affective state as indexed by rats moving to the place where they had previously experienced morphine (Rossi & Reid, 1976). A reasonable hypothesis is that morphine can potentiate activity in the medial forebrain bundle and that this potentiated activity is reflected in increased self-stimulation, in movement of rats to the place of morphine experience and in subjective reports of euphoria among human users of opiates (McAuliffe & Gordon, 1974).…”