Peripheral oxytocin administration buffers autonomic but not behavioral responses to environmental stressors in isolated prairie voles

Negative social experiences such as social stressors and isolation influence mental and physical illnesses, including affective disorders and heart disease. Studies focused on socially monogamous prairie voles can provide insight into neurobiological systems that underlie the consequences of negative social interactions. Female prairie voles were exposed to 28 days of social isolation or pairing with a female sibling (control). Voles were administered daily oxytocin [20 μg/50 μl, subcutaneous (sc)] or saline vehicle (50 μl, sc) for 14 days and exposed to two behavioral stressors [elevated plus maze (EPM) and resident-intruder test]. Brain tissue was collected for analysis of central peptide levels in the hypothalamic paraventricular nucleus (PVN). Isolation produced autonomic changes [increased heart rate (HR) and decreased HR variability) during both acute stressors and increased anxiety behaviors in the EPM. Oxytocin injection prevented the autonomic consequences of the acute stressors in isolated prairie voles, but did not affect the behaviors tested under the present conditions. Oxytocin had no effect on the behavioral or autonomic responsiveness in paired prairie voles. Oxytocin injection may exert a beneficial effect on autonomic responses to stressors in isolated animals through increasing the number of oxytocin-containing neurons and decreasing the number of corticotropin-releasing hormone-containing neurons in the PVN. Oxytocinergic mechanisms may serve to compensate for autonomic responses associated with chronic isolation and exposure to both social and non-social acute stressors.     

Identifying mediators of training effects on performance-related psychobiosocial states: A single-case observational study in an elite female triathlete

ObjectivesRelationships between training load, psychobiosocial (PBS) states and performance are dynamic and individual-specific. The nature of these relationships can be investigated using a combination of dynamic linear models (DLMs) and mediating variable analysis, potentially assisting applied sports psychologists in planning and monitoring of individual elite athletes’ intervention programmes.DesignWe illustrate this approach by examining the relationships of training loads with a performance-related state (‘self-efficacy’) and the role of potential mediating PBS variables (‘fatigue/lack of energy’ and ‘being in shape’) in explaining these relationships in an elite triathlete across time.MethodSelf-reports of PBS states (twice weekly) and training data were collected over 137 days. Using DLMs and mediating variable analysis, direct (unmediated) and indirect (mediated) short-term associations of training load with ‘self-efficacy’ were examined.ResultsIn this triathlete, we found evidence for positive effects of training on ‘self-efficacy’, which were partly explained by feelings of ‘being in shape’ and suppressed by feelings of ‘fatigue/lack of energy’. Changes in the relationship between lagged training load and ‘fatigue/lack of energy’ were observed across time and were particularly pronounced in temporal proximity of an injury.ConclusionStrengths of the presented approach are its dynamic nature enabling the observation of changes occurring over time, use of statistical inference rather than visual data interpretation, and quantification of mediating effects to identify potential pathways of intervention. Additionally, the DLM method can identify complex nonlinear associations by examining correspondence between changes in levels of predictors and changes in magnitude and direction of predictor-outcome associations.