Imparting reinforcing property to the taste of morphine through morphine injections

Abstract

The present experiment tested the hypothesis that the taste of morphine would become a secondary reinforcer for rats made physically dependent on morphine by large, rapid intravenous injections. Rats made dependent by such injections and then withdrawn licked a dilute morphine solution more during a 30-sec licking period than did nondependent rats. A second experiment indicated that rats made physically dependent on morphine by 8 days of rapid injections licked a morphine solution more during withdrawal than did rats made dependent by 8 days of slow infusions. The results supported the preliminary hypo thesis.