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Townsend E.A.,University of Mississippi Medical Center | Beloate L.N.,University of Mississippi Medical Center | Huskinson S.L.,University of Mississippi Medical Center | Roma P.G.,Institutes for Behavior Resources | And 2 more authors.
Physiology and Behavior | Year: 2015

Obesity is associated with abnormal brain reactivity in response to palatable food consumption, a factor that may contribute to non-homeostatic eating. However, little is known about how obesity interacts with the reinforcing effects of highly palatable constituents of food (e.g., fat), and if altered reinforcement processes associated with obesity generalize to non-food reinforcers. The current study compared the reinforcing effects of a fat (corn oil) and a drug of abuse (cocaine) in obese and lean Zucker rats. Specifically, obese and lean Zucker rats self-administered corn oil or intravenous cocaine in a behavioral economic demand procedure. For corn oil, maximum demand was higher and demand elasticity was lower in the obese rats compared to their lean counterparts. However, there were no differences in demand for cocaine between the obese and lean rats. These results demonstrate that a fat in the form of corn oil is a more effective reinforcer in obese Zucker rats. However, the fact that demand for cocaine was not different between the obese and lean rats suggests that differences in reward mechanisms may be reinforcer-specific and do not necessarily generalize to non-food reinforcers. © 2015.


Freeman K.B.,University of Mississippi Medical Center | McMaster B.C.,University of Mississippi Medical Center | Roma P.G.,Institutes for Behavior Resources | Roma P.G.,Johns Hopkins University | Woolverton W.L.,University of Mississippi Medical Center
Psychopharmacology | Year: 2014

Rationale: Recent research has demonstrated that the drug, histamine, can function as a punisher of cocaine self-administration. However, little is known about how drug punishers affect the maximum reinforcing effectiveness of drugs as reinforcers. Objective: The goal of the present study was to determine if histamine, when self-administered as a mixture with cocaine, could reduce cocaine's maximum reinforcing effectiveness using two procedures designed for measuring reinforcing effectiveness. Methods: In the first experiment, rhesus monkeys were allowed to self-administer cocaine (0.1 mg/kg/inj) alone or as a mixture with histamine (0.012-0.05 mg/kg/inj) in a behavioral economic design. In the second experiment, monkeys were allowed to self-administer cocaine alone (0.006-0.56 mg/kg/inj) or as a mixture with histamine (0.025-0.1 mg/kg/inj) under a progressive-ratio schedule of reinforcement. Results: In Experiment 1, histamine decreased the reinforcing effectiveness of cocaine in a dose-dependent manner as evidenced by increases in cocaine's demand elasticity with increases in histamine dose. In Experiment 2, histamine decreased cocaine's potency and effectiveness as a reinforcer in a dose-dependent manner as indicated by rightward and downward shifts, respectively, in the dose-response functions. Conclusion: The reinforcing effectiveness of cocaine can be reduced by contingent self-administration of histamine. These results indicate that combining drug punishers with drug reinforcers reduces the maximum reinforcing effect of the drug reinforcer, which suggests a use for drug punishers as a deterrent to drug abuse (e.g., as mixtures with prescription medications with abuse potential). © 2014 Springer-Verlag Berlin Heidelberg.


Mitchell S.G.,Friends Research Institute Inc. | Gryczynski J.,Friends Research Institute Inc. | Kelly S.M.,Friends Research Institute Inc. | O'Grady K.E.,University of Maryland University College | And 4 more authors.
Journal of Drug Issues | Year: 2014

This secondary analysis compared outcomes in African American adults newly admitted to buprenorphine treatment and who were on parole and probation with outcomes in patients who were not under criminal justice (CJ) supervision. Buprenorphine patients (N = 300) were randomly assigned to receive either intensive outpatient (IOP) treatment or standard outpatient (OP) treatment and were assessed at baseline, and 3 and 6 months. There were no differences between groups in treatment retention. Among probationers/parolees, IOP treatment was associated with lower 3-month treatment retention compared with OP treatment, but among participants not on probation/parole, the relationship was reversed (p = .004). Both conditions showed significant declines in heroin and cocaine use, illegal activity, and in meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) criteria for opioid and cocaine dependence. Probationers/parolees reported a lower frequency of illegal activities at 3 months compared with nonprobationers/nonparolees (p = .007). Buprenorphine treatment should be made more widely available to individuals on parole/probation as they respond as well to treatment as patients not supervised by the CJ system. © The Author(s) 2013.


Gryczynski J.,Friends Research Institute | Jaffe J.H.,Friends Research Institute | Jaffe J.H.,University of Maryland Baltimore County | Schwartz R.P.,Friends Research Institute | And 6 more authors.
American Journal on Addictions | Year: 2013

Background Recent policy initiatives in Baltimore City, MD significantly reduced access disparities between methadone and buprenorphine in the publicly funded treatment sector. Objectives This study examines reasons for choosing buprenorphine over methadone among patients with access to both medications. Method This study was embedded within a larger clinical trial conducted at two outpatient substance abuse treatment programs offering buprenorphine. Qualitative and quantitative data on treatment choice were collected for new patients starting buprenorphine treatment (n = 80). The sample consisted of predominantly urban African American (94%) heroin users who had prior experience with non-prescribed street buprenorphine (85%), and opioid agonist treatment (68%). Qualitative data were transcribed and coded for themes, while quantitative data were analyzed using descriptive and bivariate statistics. Results Participants typically conveyed their choice of buprenorphine treatment as a decision against methadone. Buprenorphine was perceived as a helpful medication while methadone was perceived as a harmful narcotic with multiple unwanted physical effects. Positive experiences with non-prescribed "street buprenorphine" were a central factor in participants' decisions to seek buprenorphine treatment. Conclusions Differences in service structure between methadone and buprenorphine did not strongly influence treatment-seeking decisions in this sample. Personal experiences with medications and the street narrative surrounding them play an important role in treatment selection decisions. Scientific Significance This study characterizes important decision factors that underlie patients' selection of buprenorphine over methadone treatment. © American Academy of Addiction Psychiatry.


Goswami N.,Medical University of Graz | Roma P.G.,Institutes for Behavior Resources | Roma P.G.,Johns Hopkins University | De Boever P.,Flemish Institute for Technological Research | And 12 more authors.
Planetary and Space Science | Year: 2012

Due to its proximity to Earth, the Moon is a promising candidate for the location of an extra-terrestrial human colony. In addition to being a high-fidelity platform for research on reduced gravity, radiation risk, and circadian disruption, the Moon qualifies as an isolated, confined, and extreme (ICE) environment suitable as an analog for studying the psychosocial effects of long-duration human space exploration missions and understanding these processes. In contrast, the various Antarctic research outposts such as Concordia and McMurdo serve as valuable platforms for studying biobehavioral adaptations to ICE environments, but are still Earth-bound, and thus lack the low-gravity and radiation risks of space. The International Space Station (ISS), itself now considered an analog environment for long-duration missions, better approximates the habitable infrastructure limitations of a lunar colony than most Antarctic settlements in an altered gravity setting. However, the ISS is still protected against cosmic radiation by the Earth magnetic field, which prevents high exposures due to solar particle events and reduces exposures to galactic cosmic radiation. On Moon the ICE environments are strengthened, radiations of all energies are present capable of inducing performance degradation, as well as reduced gravity and lunar dust. The interaction of reduced gravity, radiation exposure, and ICE conditions may affect biology and behavior - and ultimately mission success - in ways the scientific and operational communities have yet to appreciate, therefore a long-term or permanent human presence on the Moon would ultimately provide invaluable high-fidelity opportunities for integrated multidisciplinary research and for preparations of a manned mission to Mars. © 2012 Elsevier Ltd. All rights reserved.

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