Long-term development of excessive and inflexible nicotine taking by rats, effects of a novel treatment approach.

Rationale: Addiction is characterized by inflexible drug consumption: unpleasant consequences are accepted. Rat studies with several drugs proved that long-term voluntary intake induced abstinence-outlasting excessive and inflexible consumption.

Objective: Establishing a long-term model of oral self-administration of nicotine in rats with outlasting consequences for flexibility; testing a novel approach to restore flexibility by increasing neuroplasticity for memory reorganization via glucocorticoids.

An animal model of compulsive food-taking behaviour.

The increase in the incidence of obesity and eating disorders has promoted research aimed at understanding the aetiology of abnormal eating behaviours. Apart from metabolic factors, obesity is caused by overeating. Clinical reports have led to the suggestion that some individuals may develop addictive-like behaviours when consuming palatable foods, and compulsive eating plays a similar dominant role in obesity as compulsive drug taking does in drug addiction.

Loss of flexibility in alcohol-taking rats: promoting factors.

Alcohol consumption in humans can move from a flexible pattern of intake to an inflexible (addictive) one. Several endogenous and exogenous factors are discussed to be involved in this transition. The purpose of this study was to examine factors that might promote the development of inflexibility.

Long-term voluntary consumption of MDMA and THC in rats is modified by individual and situational factors.

Factors influencing long-term voluntary intake of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) and Delta9-tetrahydrocannabinol (THC; cannabis) were studied in a rat model. Sixty-four male Wistar rats were given free choice for 49 weeks between (1) water and MDMA solution, (2) water and THC solution or (3) water, MDMA solution and THC solution. After the first experiences with the drugs, animals of both monodrug and polydrug group developed an individually stable pattern of MDMA consumption, whereas the individual predictability of THC consumption remained poor.

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

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.