Abstract
Four groups (n=16/group) of rats were given ad libitum access to morphine-adulterated food in one of four different concentrations (1, 2, 3, or 4 mg morphine HCl/g milled food). Half of the subjects in each group were given ad libitum water while the other half were provided with sucrose morphine (1 mg morphine HCl/ml 10% sucrose). Daily measures of body weight, food, liquid, caloric, and morphine intake were recorded for each animal. All eight treatment regimens were effective in inducing physical dependence on morphine as shown by: a) a preference for the morphinized food (1 and 2 mg/g groups) or, b) observable withdrawal signs in rats which failed to maintain their daily morphine intake (3 and 4 mg/g groups) in a subsequent choice test between plain food and morphine-adulterated food at the respective concentration. Caloric intake for all groups was similar to a non-drugged control group. It is concluded that opiate dependence can be achieved by adulterating both the food and liquid regimen of the rat with morphine.
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This study was Supported by NSF Research Grants B023365 and P2B0349 to K. A. Khavari. The authors thank Thomas Peters and Jan Westerman for their assistance with parts of this work.
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Khavari, K.A., Risner, M.E. Concentration-ingestion relations of morphine-adulterated food and morphine solution. Psychopharmacologia 30, 45–60 (1973). https://doi.org/10.1007/BF00422793
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DOI: https://doi.org/10.1007/BF00422793