Showing papers by "Rajesh Kumar published in 1972"

Morphine dependence in rats: Secondary reinforcement from environmental stimuli

Abstract: Rats which were physically dependent on morphine were repeatedly placed in distinctive environments immediately after being injected with their daily dose of the drug (120 mg/kg). The effects of morphine, e.g. reduction of withdrawal symptoms, were thus associated with particular environmental stimuli and when the rats were tested in withdrawal, they preferred these environments to unfamiliar neutral ones. They also tended to have higher photocell activity scores during these tests. Avoidance of such environments was not shown by rats which had repeatedly been placed in them when in states of withdrawal.

Regulation of drug and water intake in rats dependent on morphine.

Abstract: Rats were made dependent on morphine by training them to drink solutions of the drug even when water was available as an alternative Experiments were carried out to examine the reliability of the technique Drinking was recorded in two ways, and it was found that there was close agreement between the numbers of laps (“drinkometer” counts) and the volumes of fluids removed from the drinking bottles When dependent rats were allowed to partially satisfy their needs for morphine and/or water shortly before morphine: water choice trials, they made appropriate adjustments in their subsequent consummatory responses However, the value of using quinine solutions to control for effects due to the bitter taste of morphine was more limited than has sometimes been supposed; the relative palatabilities of the two drugs seemed to vary across experiments Considered as a whole, the results support the view that preferences for morphine in rats can provide a valid measure of their need for the drug