Essential Value Research Articles

Relative reinforcing effects of dibutylone, ethylone, and N-ethylpentylone: self-administration and behavioral economics analysis in rats.

Following the emergence of methylone as one of the most popular synthetic cathinones, this group of novel psychoactive substance with names ending in "-lone," such as dibutylone, ethylone, and N-ethylpentylone, appeared on the recreational drug market. The pharmacological mechanisms of dibutylone, ethylone, and N-ethylpentylone are well understood; however, to date, the reinforcing effects of dibutylone, ethylone, and N-ethylpentylone are still unclear. This study aimed to examine the self-administration of dibutylone, ethylone, and N-ethylpentylone relative to methamphetamine (METH) and to quantify their relative reinforcing effectiveness using behavioral economic analysis. Male Sprague-Dawley rats were trained to self-administer METH (0.05mg/kg) under a fixed-ratio 1 (FR1) schedule. Following the training, dose substitution was used to generate full dose-response curves for METH and the three synthetic cathinones. According to the first doses on the descending limb of the dose-response curves, rats were trained to self-administer METH (0.05mg/kg), dibutylone (0.1mg·kg-1·infusion-1), ethylone (0.4mg·kg-1·infusion-1), or N-ethylpentylone (0.1mg·kg-1·infusion-1) under an FR1 schedule, and a behavioral economic evaluation of their reinforcing effectiveness was then performed. Dibutylone, ethylone, and N-ethylpentylone functioned as reinforcers, and the inverted U-shaped dose-response curves were obtained. The rank order of reinforcing potency in this procedure was METH > N-ethylpentylone ≈ dibutylone > ethylone. In the economic analysis, the comparisons of the essential value (EV) transformed from demand elasticity (α) indicated that the rank order of efficacy as reinforcers was METH (EV = 7.93) ≈ dibutylone (EV = 7.81) > N-ethylpentylone (EV = 5.21) ≈ ethylone (EV = 4.19). These findings demonstrated that dibutylone, ethylone, and N-ethylpentylone function as reinforcers and have addictive potential, suggesting that the modification of α-alkyl and N-alkyl side chains may affect their reinforcing efficacy.

Sex moderates the effects of experimentally induced musculoskeletal pain on alcohol demand in healthy drinkers

BackgroundPain may serve as an antecedent for alcohol use, increasing risk for hazardous drinking and associated consequences. Delayed onset muscle soreness (DOMS) induction produces clinically relevant but time-limited musculoskeletal pain. This study was conducted to determine whether DOMS induction on the dominant elbow flexors influenced alcohol demand using the Alcohol Purchase Task (APT). We hypothesized DOMS would increase alcohol demand relative to a sham control. Based on existing studies of pain self-medication, we expected DOMS-related increases in alcohol demand would be greatest in men. MethodsParticipants (N = 53; 57 % women) were randomly assigned to a DOMS (eccentric exercise) or sham condition (concentric exercise). Participants completed the APT pre-exercise and 48 -hs post-exercise. Repeated measures GLM was used to characterize group by sex by time interactions on APT indices, including intensity, breakpoint, essential value (EV), Omax, and Pmax. ResultsThe DOMS procedure significantly increased pain ratings at the elbow flexors. Men had significantly higher demand intensity than women across groups and time points. Significant interactive effects were detected for breakpoint and EV. From pre- to post-test, breakpoint significantly increased in men in the DOMS group. However, breakpoint and EV significantly decreased in women in the DOMS group. ConclusionsIncreased alcohol demand in men in the DOMS group was consistent with epidemiological data suggesting men are at higher risk for self-medicating pain with alcohol than women. However, decreased demand in women was unexpected. Taken together, results indicate DOMS induction may be a useful means to characterize pain as an antecedent for alcohol use.

Interpretation(s) of elasticity in operant demand.

This brief report provides an account of varying interpretations of elasticity (η) in the operant demand framework. General references to "demand elasticity" have existed since the Exponential model of operant demand was proposed by Hursh and Silberberg (2008). This term has been used interchangeably with Essential Value (EV), PMAX , and the rate of change constant α. This report provides an in-depth account of η and the various ways in which this metric has been used to interpret fitted demand functions. A review of relevant mathematic terms, operations associated with differentiating parameters, and worked solutions for η are provided for linear and nonlinear demand functions. The relations between η and EV, PMAX , and α are described and explained in terms of their mathematical bases and recommendations are provided regarding their individual interpretation. This report concludes with recommendations for providing additional mathematical detail in published works and emphasizing a consistent use of terms when describing aspects of operant demand.

The effects of next-day class characteristics on alcohol demand in college students.

Behavioral economic principles have been useful for addressing strategies to reduce alcohol consumption among college students. For example, academic variables (such as class schedule or academic rigor) have been found to affect alcohol demand assessed with a hypothetical alcohol purchase task (APT). The present studies used the APT to address the effects of 2 academic variables: next-day course level (no class, introductory level or upper level) and class size (no class, 30-student or 12-student). In each of 2 experiments, undergraduate participants read a description of a drinking context (either a no-class control version or 1 of the academic constraint conditions) and were asked to indicate how many drinks they would purchase at a variety of prices. Hursh and Silberberg's (2008) exponential demand equation was used to determine intensity and elasticity of demand, and Hursh and Roma's (2015) essential value (EV) parameter was calculated to assess essential value. In both experiments, a next-day class reduced alcohol demand, and alcohol consumption decreased as drink price increased. The presence of a smaller next-day class reduced alcohol demand compared with a larger next-day class; however, course level did not differentially affect alcohol demand. These results suggest that smaller next-day classes may reduce alcohol demand among college students and also provide initial evidence for the reliability of EV across studies. (PsycINFO Database Record