Sucrose intake predicts rate of acquisition of cocaine self-administration

Abstract 

Rationale: A number of studies have indicated a relationship between the intake of palatable foods or fluids and drug self-administration. Objectives: Two experiments were conducted to determine whether the intake of sucrose or fat was related to subsequent cocaine self-administration. Methods: In separate groups of rats, sucrose or fat was presented for 60 min daily for 7 days. On day 8, a mild stressor (saline injection) was given just prior to sucrose or fat presentation. Rats were then catheterized and tested for cocaine self-administration on a fixed ratio schedule at doses from 0.2 mg/kg to 1.0 mg/kg per infusion and on a progressive ratio schedule at doses from 0.2 mg/kg to 1.5 mg/kg per infusion. Results: Sucrose intake after a mild stressor was significantly related to time to acquisition, with those rats consuming the most sucrose meeting the acquisition criterion sooner than those rats consuming lower amounts of sucrose. Subsequent to acquisition, however, low and high sucrose feeders did not consistently differ in the amount of cocaine self-administered. No relationship was observed between fat intake and rate of acquisition. Conclusion: These results provide additional evidence of a relationship between sucrose intake and drug reward, and suggest that stress reactivity may be an important component of this relationship.