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bioRxiv · 10.1101/2020.11.06.370023

The Effects of Strain and Estrous Cycle on Heroin- and Sucrose-Maintained Responding in Female Rats

Schmidt, K. T.·Sharp, J. L.·Ethridge, S. B.·Pearson, T.·Ballard, S.·Potter, K. M.·Smith, M. A.
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Abstract

Heroin intake decreases during the proestrus phase of the estrous cycle in female, Long-Evans rats. The purpose of this study was to (1) determine if proestrus-induced decreases in heroin intake extend across rat strains and (2) determine if proestrus-induced decreases in responding extend to a nondrug reinforcer. Female rats were implanted with intravenous catheters and trained to self-administer heroin. Estrous cycle was tracked daily for the duration of the study. During testing, Lewis, Sprague-Dawley, and Long Evans rats self-administered low (0.0025 mg/kg) and high (0.0075 mg /kg) doses of heroin (Experiment 1) and then self-administered sucrose (Experiment 2) on fixed ratio (FR1) schedules of reinforcement. Heroin intake decreased significantly during proestrus in all three rat strains under at least one dose condition; however, sucrose intake did not decrease during proestrus in any strain. These data indicate that responding maintained by heroin, but not a nondrug reinforcer, significantly decreases during proestrus in female rats and that these effects are consistent across rat strain.

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Schmidt, K. T., Sharp, J. L., Ethridge, S. B., Pearson, T., Ballard, S., Potter, K. M., Smith, M. A.. 2020-11-08. The Effects of Strain and Estrous Cycle on Heroin- and Sucrose-Maintained Responding in Female Rats. https://doi.org/10.1101/2020.11.06.370023

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