Incentive motivation for palatable food blocked by intra-accumbens melanin-concentrating hormone (MCH) receptor-1 antagonist in female rats.

Melanin-concentrating hormone (MCH) activity in the nucleus accumbens (Acb) has been shown to influence feeding behavior, yet this has not been characterized in terms of homeostatic vs. hedonic feeding processes. Hedonic feeding, driven by palatability rather than energy deficit, can be modeled through intra-Acb administration of the selective µ-opioid receptor agonist d-Ala2, NMe-Phe4, Glyol5-enkephalin (DAMGO), which preferentially increases consumption and incentive motivation to obtain preferred palatable food. Pharmacological activation of MCH 1 receptors (MCHR1) within Acb has been shown to promote general feeding of chow in males, but not females. However, the effects of MCH on the incentive motivation to obtain preferred palatable food have not been explored. Here, we investigated the role of MCHR1 within the Acb in DAMGO-induced incentive motivation to obtain a sucrose pellet reward. Female Sprague Dawley rats were trained and tested for operant responding under a progressive ratio (PR) breakpoint in response to concurrent intra-Acb administration of DAMGO (0 µg and 0.025 µg/.5 µl/side) immediately following intra-Acb administration of the MCHR1 antagonist (N-(3-{1-[4-(3,4-difluoro-phenoxy)-benzyl]-piperdin-4-yl}-4-methyl-phenyl)-isobutyramide (SNAP-94847; 0 µg, 1.5 µg, and 15 µg/.5 µl/side), in a counterbalanced fashion. As expected, DAMGO significantly increased PR breakpoint and overall active lever presses. SNAP-94847 did not influence PR breakpoint by itself, compared to vehicle; however, both 1.5 and 15 µg doses of SNAP-94847 significantly blocked the increased PR breakpoint produced by intra-Acb DAMGO. The results of the study demonstrate that Acb MCHR1 may play a specific role in the hedonically-driven motivation for palatable food in females.

Voluntary wheel running access produces opposite effects in male and female rats on both palatable diet consumption and associated ventral striatal opioid- and dopamine-related gene expression.

The relationship between physical activity levels and feeding behaviors has been a focus of preclinical research for decades, yet this interaction has only recently been explored for potential sex differences. The aim of the present study was to isolate sex-dependent effects of voluntary wheel running (RUN) vs. sedentary locked wheel (SED) home cage conditions on palatability-driven feeding behavior using a 2-diet choice task between standard chow and a high-fat diet. The sex-dependent effects of physical activity on feeding behavior were examined following a within-subject novel reversal design of physical activity conditions (i.e., RUN > SED > RUN), to assess temporal sensitivity of the interaction. Following the final 2 weeks of reestablished and sustained RUN vs. SED conditions in separate groups of both males and females, reward-related opioid and dopamine gene expression within the nucleus accumbens (Acb) brain region were analyzed. Results demonstrated that the initial RUN > SED transition led to sex-dependent effects of SED condition, as males increased, and females decreased their high fat consumption, compared to their respective high fat consumption during previous RUN condition phase. Following reintroduction to the RUN condition, males decreased, and females increased their high fat consumption, compared to their separate SED control group. Last, sex-dependent shifts in ventral striatal opioid- and dopamine-related gene expression were observed to parallel the behavioral effects. The major findings of the study reveal that SED and RUN home cage conditions shift palatability-driven feeding in the opposite direction for males and females, these effects are sensitive to reversal, and these sex-dependent feeding behaviors track sex-dependent changes to critical reward-related gene expression patterns in the Acb. Considering the present high rates of sedentary behavior and obesity, furthering our understanding of the interaction between physical activity (or lack thereof) and feeding behavior should be a priority, especially in the context of these divergent sex-dependent outcomes.

The mobile everyday cognition scale (mECog): development and pilot testing.

Objective: Subjective cognitive decline (SCD) is an important part of the aging process and may be a sign of neurodegenerative disease. Current measures of SCD are subject to the limits of retrospective recall of symptoms over a long span of time, which might be addressed by using ecological momentary assessment (EMA) methods. However, there are no currently available measures of SCD validated for use in EMA. Thus, our goal was to develop and pilot test the mobile Everyday Cognition Scale (mECog). Method: 31 community-dwelling older adults completed in lab measures of cognition and mental health symptoms, followed by daily mECog ratings on a smart phone for 28 days. Results: Most participants completed at least 75% of mECog assessments (n = 27, 87%), and the average number of assessments completed was 22. Further, respondents rated the mobile assessment platform and measures as easy to use and non-interfering with daily life. Test-retest reliability of mECog scores was very strong (RKRN = .99), and within-person reliability was moderate (RCN = .41). mECog scores demonstrated strong positive associations with scores from the original ECog (ρ = .62-69, p < .001) and short form ECog (ρ = .63-.69, p < .001) and non-significant associations with demographics (ρ = -0.25-.04, p = .21-.94) and mental health symptoms (ρ = -0.06-.34, p = .08-.99). mECog scores also exhibited small-to-moderate negative correlations with objective cognitive test scores, though these relationships did not reach statistical significance (ρ = -0.32 to -0.22, p = .10-.27). Conclusions: Results suggest that mobile assessment of SCD via the mECog is feasible and acceptable. Further, mECog scores demonstrated good psychometric properties, including evidence of strong reliability, convergent validity, and divergent validity.