Influence of psychogenetics in opiate tolerance and abstinence in mice.

1. Four different strains of mice were used to study the influence of psychogenetics in opiate tolerance and abstinence. 2. The CD1 strain seemed to be more sensitive to naloxone administration after four days of morphine implantation, because administration of the antagonist induces a number of jumps in the withdrawal phase higher than in the case of the DBA or C3H strains. 3. DBA and C3H mice elicit analgesia before the CD1 strain, whereas the C3H mice lose body weight at a faster rate than the other strains. 4. C57 bl mice died after morphine implantation (100%). 5. These findings are discussed in relation with neurochemical and receptor variations.