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The investigation of rodent cocaine self-administration (SA) under conditions that promote escalating patterns of intake may provide insight into the loss of control over drug use that is central to human addiction.

This study examines the effects of daily long-access (LgA) SA of high or low cocaine doses on drug intake, extinction, reinstatement, and brain mRNA levels.

Three groups of male Sprague-Dawley rats were trained to self-administer cocaine during multiple-dose sessions. Short-access (ShA) rats were tested daily for multi-dose SA then remained in the chambers for 7 h with no cocaine available. LgA rats had access to low (0.5 mg/kg per infusion; LgA-LD) or high (2.0 mg/kg per infusion; LgA-HD) cocaine doses for 7 h after multi-dose SA. After 14 days, responding was extinguished …