Acute and chronic cocaine enchance perseverative reward seeking in rats: implications for comorbid pathological gambling and cocaine abuse
'Rationale.' The rate of pathological gambling is high amongst cocaine abusers. However, the nature of the relationship between these disorders is unclear. 'Objective.' To study, using rats, the effect of acute and chronic cocaine administration on perseverative reward seeking, an aspect of pathological gambling. 'Methods and results.' Rats were trained to press for sucrose on concurrent fixed ratio 25 (FR25) and variable ratio 15 (VR15) schedules. Perseverative reward seeking was assessed by replacing the VR15 schedule with a progressive ratio (PR) schedule. Perseverance of responding on the PR lever was reduced by both food satiety and repeated testing. In contrast, both acute (1 and 3 mg/kg, IP) and chronic cocaine exposure (15 or 30 mg/kg/day IP x 5 days) increased perseveration. 'Conclusions'. These results provide some evidence that cocaine can increase perseverative reward seeking, possibly making chronic cocaine users more susceptible to develop chasing behaviour.