COCAINE SELF-ADMINISTRATION IN OVARIECTOMIZED RATS IS PREDICTED BY RESPONSE TO NOVELTY, ATTENUATED BY 17-BETA ESTRADIOL, AND ASSOCIATED WITH ABNORMAL VAGINAL CYTOLOGY

Parameters of cocaine self-administration behavior and vaginal cytolog ical changes were assessed in ovariectomized rats during and after chr onic self-administration. Response to novelty as measured by locomotor activity was found to correlate with cocaine self-administration on b oth fixed ratio (FR) and progressive ratio (PR) schedules of reinforce ment. Chronic 17-beta estradiol (E-2) replacement did not affect cocai ne self-administration on FR or PR schedules of reinforcement. Acute E -2 administration decreased cocaine self-administration on a PR schedu le of reinforcement on the day of and on the two days following hormon e treatment. Finally, the proliferation of vaginal epithelia following acute E-2 was potentiated in rats both during cocaine self-administra tion and 30 days into withdrawal when compared with non-drug-exposed a nimals. These results identify response to novelty as a behavioral ind ex predictive of cocaine self-administration liability in female rats and additionally provide evidence of psychostimulant-hormonal interact ions highly relevant to female behavior and physiology. (C) 1997 Elsev ier Science Inc.