Dimorfismo sexual en el comportamiento altruista de jóvenes colombianos: correlatos electrofisiológicos y endocrinos

La especie humana se caracteriza por un alto nivel de complejidad en sus interacciones y estructuras sociales. Para Dunbar (1998), esta fue la principal razón que podría explicar el crecimiento relativo del cerebro, principalmente el lóbulo frontal, en nuestra especie y otros primates no humanos afines filogenéticamente. Las explicaciones de este autor parten de que un entorno social complejo generaría una mayor exigencia cognitiva para los individuos, dado que, para lograr eficacia en sus interacciones, deben aumentar su capacidad para recordar y manipular información social, reconocer las jerarquías y roles, reconocer estados emocionales y anticipar intenciones de otros individuos, así como realizar comportamientos estratégicos como el engaño táctico y el establecimiento de alianzas.1a edició

Randomized controlled evaluation of the psychophysiological effects of social support stress management in healthy women.

Considering the high and increasing prevalence of stress, approaches to mitigate stress-related biological processes become a matter of public health. Since supportive social interactions contribute substantially to mental and physical health, we set out to develop a social support stress management intervention and examined its effects on psychophysiological stress responses as well as self-reported stress in healthy women. In a parallel-group randomized controlled trial, registered in the DSRK (DRKS00017427), 53 healthy women were randomly assigned to a social support stress management or a waitlist control condition. All participants underwent a standardized psychosocial stress test where physiological and emotional stress responses were assessed by repeated measurements of cortisol, heart rate, heart rate variability and state anxiety. Also, all participants completed self-report questionnaires of perceived stress and social support at pre-intervention, post-intervention and follow-up four weeks later. Participants in the social support stress management showed a significantly attenuated integrated state anxiety response in comparison to those in the control condition, but conditions did not differ in any of the assessed physiological stress responses. The intervention significantly reduced perceived stress in comparison to the control condition, but perceived stress levels returned to baseline at follow-up. Our results indicated that the intervention had no effect on physiological responses to acute psychosocial stress, even though anxiety responses to stress were attenuated. However, the social support stress management intervention had a significant, albeit transient impact on perceived stress

CD36 is involved in oleic acid detection by the murine olfactory system

Olfactory signals influence food intake in a variety of species. To maximize the chances of finding a source of calories, an animal's preference for fatty foods and triglycerides already becomes apparent during olfactory food search behavior. However, the molecular identity of both receptors and ligands mediating olfactory-dependent fatty acid recognition are, so far, undescribed. We here describe that a subset of olfactory sensory neurons expresses the fatty acid receptor CD36 and demonstrate a receptor-like localization of CD36 in olfactory cilia by STED microscopy. CD36-positive olfactory neurons share olfaction-specific transduction elements and project to numerous glomeruli in the ventral olfactory bulb. In accordance with the described roles of CD36 as fatty acid receptor or co-receptor in other sensory systems, the number of olfactory neurons responding to oleic acid, a major milk component, in Ca2+ imaging experiments is drastically reduced in young CD36 knock-out mice. Strikingly, we also observe marked age-dependent changes in CD36 localization, which is prominently present in the ciliary compartment only during the suckling period. Our results support the involvement of CD36 in fatty acid detection by the mammalian olfactory system

Endogenous cortisol and conditioned placebo effects on pain - A randomized trial

Placebo effects can be induced by learning and conditioning processes, which in turn are influenced and modulated by glucocorticoids. Accordingly, previous research has shown that intervention-related associative learning can be modulated through exogenous as well as endogenous glucocorticoids. Thus, the aim of this study was to elucidate whether placebo effects induced by conditioning is modulated by daily fluctuations of endogenous cortisol levels in healthy male and female subjects. Overall 77 participants underwent a two-phased placebo conditioning paradigm for pain analgesia. Subjects were randomized in two groups, which underwent placebo preconditioning either in the morning (08:00-10:00, i.e. with high endogenous cortisol levels) or in the afternoon (16:00-18:00, i.e. with low endogenous cortisol levels). Placebo effects were assessed two days later at noontime (12:00-13:00), with possible differences between groups as an indicator of glucocorticoid modulation on the placebo learning. Results indicated a significant conditioned placebo-induced analgesia, resulting in a placebo effect of small to medium size. Cortisol levels on conditioning day significantly differed between groups and cortisol levels were similar during assessment of placebo effects. Groups did not differ in their mean reduction in pain sensation, thus the placebo effect was not affected by differences in cortisol levels during the conditioning of placebo effects. The present study does not indicate a moderation of placebo conditioning by endogenous glucocorticoid levels

Dexamethasone suppression test predicts later development of an impaired adrenal function after a 14-day course of prednisone in healthy volunteers

Suppression of the adrenal function after glucocorticoid treatment is common, potentially dangerous, and unpredictable. Identification of patients at risk is of clinical importance. We hypothesized that the dexamethasone suppression test predicts the development of corticosteroid-induced impaired adrenal function

What should clinicians tell patients about placebo and nocebo effects? Practical considerations based on expert consensus

INTRODUCTION: Clinical and laboratory studies demonstrate that placebo and nocebo effects influence various symptoms and conditions after the administration of both inert and active treatments. OBJECTIVE: There is an increasing need for up-to-date recommendations on how to inform patients about placebo and nocebo effects in clinical practice and train clinicians how to disclose this information. METHODS: Based on previous clinical recommendations concerning placebo and nocebo effects, a 3-step, invitation-only Delphi study was conducted among an interdisciplinary group of internationally recognized experts. The study consisted of open- and closed-ended survey questions followed by a final expert meeting. The surveys were subdivided into 3 parts: (1) informing patients about placebo effects, (2) informing patients about nocebo effects, and (3) training clinicians how to communicate this information to the patients. RESULTS: There was consensus that communicating general information about placebo and nocebo effects to patients (e.g., explaining their role in treatment) could be beneficial, but that such information needs to be adjusted to match the specific clinical context (e.g., condition and treatment). Experts also agreed that training clinicians to communicate about placebo and nocebo effects should be a regular and integrated part of medical education that makes use of multiple formats, including face-to-face and online modalities. CONCLUSIONS: The current 3-step Delphi study provides consensus-based recommendations and practical considerations for disclosures about placebo and nocebo effects in clinical practice. Future research is needed on how to optimally tailor information to specific clinical conditions and patients' needs, and on developing standardized disclosure training modules for clinicians