Long-term voluntary D-amphetamine consumption and behavioral predictors for subsequent D-amphetamine addiction in rats.

摘要

Flexibility of drug taking is characteristic for "controlled" drug consumption whereas addiction is reflected by inflexibility and persistent high risk to relapse. Male Wistar rats (N = 12) that were given a continuous free choice between water and D-amphetamine solutions for 16 weeks, revealed a moderate and flexible pattern of D-amphetamine intake when tested again after 36 weeks of drug deprivation. A second group of rats had the same choice between water and D-amphetamine for 42 weeks. In the retest after abstinence, six out of 12 rats showed a moderate and flexible pattern of intake whereas the other animals revealed an excessively high and inflexible D-amphetamine consumption. They took high doses despite an adverse bitter taste of the drug solutions caused by addition of quinine. After 39 weeks of moderate D-amphetamine intake in the long-term period exactly the same animals had spontaneously and suddenly increased their D-amphetamine consumption. In a retrospective view, the later inflexible D-amphetamine consumers had already shown differences to their flexible conspecifics before their first drug access. During "tetradic" encounter tests the later "inflexible" animals were more interested in non-social stimuli than the later "flexible" ones. The results are discussed in respect to predisposition factors that might facilitate or inhibit the development of loss of control over drug intake.