Browsing Psychology by Subjects
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Exploration of basal diurnal salivary cortisol profiles in middle-aged adults: Associations with sleep quality and metabolic parametersThe use of saliva samples is a practical and feasible method to explore basal diurnal cortisol profiles in free-living research. This study explores a number of psychological and physiological characteristics in relation to the observed pattern of salivary cortisol activity over a 12-h period with particular emphasis on sleep. Basal diurnal cortisol profiles were examined in a sample of 147 volunteers (mean age 46.2177.18 years). Profiles were constructed for each volunteer and explored in terms of the area under the curve (AUC) of the cortisol-awakening response with samples obtained immediately upon waking (0, 15, 30 and 45 min post waking) and at 3, 6, 9 and 12 h post waking to assess diurnal decline. Diurnal mean of cortisol was based on the mean of cortisol at time points 3, 6, 9 and 12 h post waking. Psychological measures of perceived stress and sleep were collected with concurrent biological assessment of fasting plasma glucose, insulin, blood lipids and inflammatory markers. Blunted cortisol profiles, characterised by a reduced AUC, were observed in the majority (78%) of a middle-aged sample and were associated with significantly poorer sleep quality and significantly greater waist-hip ratio (WHR). Blunted cortisol profiles were further associated with a tendency to exhibit a less favourable metabolic profile. These findings suggest that reduced cortisol secretion post waking may serve as an additional marker of psychological and biological vulnerability to adverse health outcomes in middle-aged adults.
A systematic review and quantitative meta-analysis of the effects of oxytocin on feedingThe anorexigenic effects of oxytocin have been widely documented and accepted; however, no study has yet used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines to compile previous findings in a single systematic review and quantitative meta-analysis. The present review aimed to identify published and unpublished studies examining the effects of oxytocin on energy intake in animals and humans, as well as the factors that moderate this effect. Web of Science, Pub Med and Ovid were searched for published and unpublished studies reporting the effects of oxytocin on energy intake in wild-type animals and in humans when administered in the absence of other active drugs or surgery. Two thousand and forty-nine articles were identified through the original systematic literature search, from which 54 articles were identified as being relevant for inclusion in the present review. An additional 3 relevant articles were identified in a later update of the literature search. Overall, a single dose of oxytocin was found to reduce feeding in animals. Despite several individual studies reporting that this effect persists to the end of the third week of chronic administration in rodent models, overall, this anorexigenic effect did not hold in the meta-analyses testing the effects of chronic administration. There was no overall effect of oxytocin on energy intake in humans, although a trend was identified for oxytocin to reduce the consumption of solid foods. Oxytocin reduces energy intake when administered as a single dose. Oxytocin can inhibit feeding over 2- to 3-week periods in rodent models. These effects typically do not persist beyond the third week of treatment. The anorexigenic effect of oxytocin is moderated by pregnant status, dose, method of administration and diet composition.