Abstract
The present study established a novel mouse model of a runway drug self-administration in our laboratory. The operant runway apparatus consisted of three long runways arranged in a zig-zag manner. The methodology consisted of six distinct phases: habituation, preconditioning, conditioning, post-conditioning, extinction and reinstatement. The effects of saline were compared with escalating doses of either ethanol (0.5–4.0 g/kg, i.p), heroin (5–40 mg/kg, i.p), or nicotine (0.1–0.5mg/kg, i.p) administered in the goal box during the conditioning phase (day 1 to day 5). A significant decrease in the time of trained (conditioned) mice to reach the goal box confirmed the subjects’ motivation to seek those drugs on day 6 (expression). The mice were then subjected to non-rewarded extinction trials for 5 days over which run times were significantly increased. After 5 days of abstinence, a priming dose of ethanol or heroin (1/5th of maximum dose used in conditioning) significantly reinstated the drug-seeking behavior. These results suggest that the modified runway model can serve as a powerful behavioral tool for the study of the behavioral and neurobiological bases of drug self-administration and, as such, is appropriate simple but powerful tool for investigating the drug-seeking behavior of laboratory mice.
Highlights
The present study established a novel mouse model of a runway drug self-administration in our laboratory
Earlier reports demonstrated the self-administration of addictive drugs using a rat operant runway model[4], but no such model exists for the study of drug-seeking in the mouse
We describe a modified runway paradigm that serves to lengthen the time required for the animal to reach the goal box, thereby limiting concerns about possible “floor effects” that can obscure group differences in animals that traverse the apparatus quickly
Summary
The present study established a novel mouse model of a runway drug self-administration in our laboratory. SEM) run times during preconditioning and postconditioning of mice traversing a modified runway for access to different drugs delivered upon goal-box entry (n = 9/group).
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