Rats with high propensity to ingest sugar (HIGH) show increased responsiveness to
amphetamine treatments than rats with low propensity to ingest sugar (LOW). Intrinsic …

The effects of morphine and naloxone were compared on the locomotor activity of
nondependent, morphine-dependent, and post-dependent rats. Dependence was induced …

A possible interaction between the opposite effect (inhibition and stimulation) of morphine
on locomotor activity in mice and monoaminergic systems in the striatum was studied. Ten …

Rats exhibit profound individual differences in their propensity to ingest sugar and in their
locomotor response to AMP. Intrinsic variation in the responsiveness of mesolimbic …

Rats of the Lewis inbred strain have been shown to self-administer more morphine than rats
of the inbred Fischer 344 (F344) strain. Because morphine reward and opioid-induced …

The effects of morphine on locomotor activity and cerebral dopamine (DA) and
noradrenaline (NA) metabolism were studied in mice treated repeatedly with morphine for 5 …

Rats were raised from weaning (21 days old) to young adulthood (50–60 days old) in either
an enriched or impoverished stimulus environment. In the enriched condition (EC), rats were …

Ten, seventeen and twenty-four day old rats were observed using a behavioral-time
sampling procedure following injection of saline, 0.1, 0.5, 1.0 or 5.0 mg/kg/5cc morphine …

When measured for weight loss, mortality and degree of physical dependence, 4 strains of
mice exhibited widely differing sensitivities to chronically administered morphine. However …

The effects of morphine on hamster locomotor activity were studied. Repeated
administration of morphine in doses from 5 to 40 mg/kg produced systematic changes in …