Insulin, dopamine D2 receptors, and monetary reward discounting: A common pathway for food and drug addiction

s / Drug and Alcohol Dependence 140 (2014) e2–e85 e73 has been described in healthy volunteers, the relapsedMDI did not show differential insula activation during risky versus safe choices. Thus, inadequate processing of risk within the insular cortex may predict who is likely to relapse after cessation of drug use. Financial support: This work was supported by the National Institute on Drug Abuse (R01-DA016663, P20-DA027834, R01DA027797, and R01-DA018307 to Martin Paulus). http://dx.doi.org/10.1016/j.drugalcdep.2014.02.217 Use of a sliding schedule enhances cocaine self-administration in a human laboratory setting: Relevance for relapse prevention Kenneth Grasing, V. Panwar, Aashish Morani, R. Singh Substance Abuse Research Laboratory, VA Medical Center, Kansas City, MO, United States Aims: Drug self-administration by humans is considered to be a highly predictive laboratory measure for developing mediations to prevent relapse. However, we observed relatively low levels of drug taking under a previously described procedure in which participants chose between receiving cocaine or ascending amounts of an alternativemonetary reward. Therefore,wedeveloped a slidingscale schedule in which cash reinforcement is not available until at least some drug infusions have been self-administered. Afterwards, the amount of cash available is adjusted according to rates of drug taking. The present studywas designed to compare cocaine self-administration under the two schedules. Methods: 13 participants with a history of regular cocaine use were evaluated as they intravenously self-administered0.46mg/kg of cocaine or saline using a patient-controlled analgesia pump in a laboratory setting. Prior to self-administration, that dose of cocaine or its placebowasmade available noncontingently. For both schedules, drug was delivered under a fixed-ratio-5 contingency. Results: Under the standard, ascending schedule participants self-administered relatively few infusions per session. Use of the sliding schedule increased thenumberof self-administered cocaine infusions (3.58±0.34 vs 1.50±1.03, for sliding and standard, respectively). Self-administration of intravenous placebo was also increased under the sliding schedule (4.00±0.61 vs 0.25±0.22). Response latency did not differ across schedules. Conclusions: The choice of receiving cocaine or an ascending amount of cash supported a relatively low level of drug taking in this group of participants. Itwas feasible to use of a sliding schedule which initially did not offer an alternative reinforcer, and subsequently controlled its rate of increase. The latter schedule increased self-administration of either cocaine or placebo, and may be more suitable for studies seeking to attenuate drug-reinforced behavior. Financial support: SupportedbyGrantR21-DA029787 fromthe NIH, Institute on Drug Abuse. http://dx.doi.org/10.1016/j.drugalcdep.2014.02.218 Insulin, dopamine D2 receptors, and monetary reward discounting: A common pathway for food and drug addiction Danuta M. Gredysa, S. Eisenstein, J. Antenor-Dorsey, A. Arbelaez, J. Koller, K. Black, S. Klein, J. Perlmutter, S. Moerlein, Arpana Agrawal, T. Hershey Washington University School of Medicine, St. Louis,