title: [Assessment of morphine-type physical dependence liability in mice using the drug-admixed food method].
abstract: Physical dependence on morphine-type drugs (morphine, codeine and pethidine) in mice were examined by the drug-admixed food method. Mice were treated with drug-admixed food of increasing concentration (1, 2 and 3 mg/g food) every third day for 9 days. Morphine- and codeine-treated mice showed withdrawal signs when they were given naloxone (5 mg/kg, s.c.), while pethidine-treated mice did not show the withdrawal signs. However, mice treated with pethidine-admixed food (1-6 mg/g food) for 28 days showed naloxone precipitated withdrawal signs. Thus, the data obtained with mice indicate that pethidine produces a weak physical dependence. On the other hand, codeine (40 mg/kg, s.c.) and pethidine (100 mg/kg, s.c.) administration suppressed the abrupt withdrawal signs of morphine-dependent mice that were treated with morphine-admixed food, while the withdrawal signs were completely suppressed in mice administered only 5 mg/kg morphine. These results suggest that the physical dependence liability of morphine type drugs can be predicted by the drug-admixed food method.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D003061:Codeine; D004195:Disease Models, Animal; D006801:Humans; D008297:Male; D008614:Meperidine; D051379:Mice; D008813:Mice, Inbred ICR; D009021:Morphine Dependence; D009270:Naloxone; D009293:Opioid-Related Disorders; D013375:Substance Withdrawal Syndrome; D014116:Toxicology / Q000379:methods
chemical_list: D009270:Naloxone; D008614:Meperidine; D003061:Codeine