Circadian Variation in Cortisol Reactivity to an Acute Stressor

To investigate the role of the circadian pacemaker in cortisol reactivity to a cold pressor challenge, 26 diurnally subjects participated in a constant‐routine protocol and were divided into two groups. Group 1 started immediately after a monitored sleep period at 09:00 h, while group 2 started 12 h later. After 2 h of adaptation, a cold pressor test was presented every 3 h. The cortisol response was assessed by means of saliva samples that were taken before and after the test. The pretest samples were considered to be base‐rate measures and base‐rate values as subtracted from post‐test values were considered as reactivity measures. Both measures showed distinct Time‐of‐Day variations (respectively: F_7,168 = 16.92, p < 0.001, ε = 0.383; and F_7,175 = 8.01, p < 0.001, ε = 0.523). These findings are interpreted as evidence for the existence of an endogenous circadian periodicity underlying the sensitivity of the hypothalamus–pituitary–adrenal (HPA)‐axis to acute stress.     

Psychosocial Functioning Improves Following Adolescent Bariatric Surgery

The aims of the present study were to examine changes in health‐related quality of life (HRQOL) and depressive symptoms in adolescents with extreme obesity undergoing Roux‐en‐Y gastric bypass (RYGBP) across the first postoperative year. A prospective longitudinal observational study of 31 adolescent patients undergoing RYGBP at a pediatric medical center (mean = 16.4 years; 64.5% females, mean BMI 63.5; 97% of study eligible and consecutive patients) was conducted. Participants completed two adolescent HRQOL measures, the PedsQL (generic) and the IWQOL‐Kids (weight‐related), the Beck Depression Inventory (BDI), and height and weight were measured at three time points: baseline, and 6 and 12 months following RYGBP. Prior to RYGBP, significant impairments in HRQOL were documented and 38.7% reported depressive symptomatology in the clinical range. As expected, BMI and depressive symptoms decreased and HRQOL improved from baseline to 12 months post‐RYGBP. Linear mixed modeling analyses detected several nonlinear slopes in BMI, depressive symptoms, and the majority of HRQOL domains over time with deceleration in these postoperative changes beginning at the 6th month time point. In contrast, the rate of change in weight‐related social relations was linear (e.g., no deceleration), indicating continued improvement across the first postoperative year. Adolescent RYGBP results in significant improvement in HRQOL and depressive symptomatology over the first postoperative year. Longer‐term follow‐up will be critical to determine adolescent weight and psychosocial trajectories, their interrelations, and what role psychosocial status plays in continued weight loss, maintenance, and regain.     

Coping with an Acute Psychosocial Challenge: Behavioral and Physiological Responses in Young Women

Despite the relevance of behavior in understanding individual differences in the strategies used to cope with stressors, behavioral responses and their relationships with psychobiological changes have received little attention. In this study on young women, we aimed at analyzing the associations among different components of the stress response and behavioral coping using a laboratory psychosocial stressor. The Ethological Coding System for Interviews, as well as neuroendocrine, autonomic and mood parameters, were used to measure the stress response in 34 young women (17 free-cycling women in their early follicular phase and 17 oral contraceptive users) subjected to the Trier Social Stress Test (TSST) and a control condition in a crossover design. No significant differences in cardiac autonomic, negative mood and anxiety responses to the stressor were observed between the two groups of women. However, women in the follicular phase showed a higher cortisol response and a larger decrease in positive mood during the social stress episode, as well as greater anxiety overall. Interestingly, the amount of displacement behavior exhibited during the speaking task of the TSST was positively related to anxiety levels preceding the test, but negatively related to baseline and stress response values of heart rate. Moreover, the amount of submissive behavior was negatively related to basal cortisol levels. Finally, eye contact and low-aggressiveness behaviors were associated with a worsening in mood. Overall, these findings emphasize the close relationship between coping behavior and psychobiological reactions, as well as the role of individual variations in the strategy of coping with a psychosocial stressor.     

Retrieval Intention Modulates the Effects of Directed Forgetting Instructions on Recollection

The neurocognitive basis of memory retrieval is often examined by investigating brain potential old/new effects, which are differences in brain activity between successfully remembered repeated stimuli and correctly rejected new stimuli in a recognition test. In this study, we combined analyses of old/new effects for words with an item-method directed-forgetting manipulation in order to isolate differences between the retrieval processes elicited by words that participants were initially instructed to commit to memory and those that participants were initially instructed to forget. We compared old/new effects elicited by to-be-forgotten (TBF) words with those elicited by to-be-remembered (TBR) words in both an explicit-memory test (a recognition test) and an implicit-memory test (a lexical-decision test). Behavioral results showed clear directed forgetting effects in the recognition test, but not in the lexical decision test. Mirroring the behavioral findings, analyses of brain potentials showed evidence of directed forgetting only in the recognition test. In this test, potentials from 450–650 ms (P600 old/new effects) were more positive for TBR relative to TBF words. By contrast, P600 effects evident during the lexical-decision test did not differ in magnitude between TBR and TBF items. When taken in the context of prior studies that have linked similar parietal old/new effects to the recollection of episodic information, these data suggest that directed-forgetting effects manifest primarily in greater episodic retrieval by TBR than TBF items, and that retrieval intention may be important for these directed-forgetting effects to occur.     

Effect of Acute Stressor and Serotonin Transporter Genotype on Amygdala First Wave Transcriptome in Mice

The most prominent brain region evaluating the significance of external stimuli immediately after their onset is the amygdala. Stimuli evaluated as being stressful actuate a number of physiological processes as an immediate stress response. Variation in the serotonin transporter gene has been associated with increased anxiety- and depression-like behavior, altered stress reactivity and adaptation, and pathophysiology of stress-related disorders. In this study the instant reactions to an acute stressor were measured in a serotonin transporter knockout mouse model. Mice lacking the serotonin transporter were verified to be more anxious than their wild-type conspecifics. Genome-wide gene expression changes in the amygdala were measured after the mice were subjected to control condition or to an acute stressor of one minute exposure to water. The dissection of amygdalae and stabilization of RNA was conducted within nine minutes after the onset of the stressor. This extremely short protocol allowed for analysis of first wave primary response genes, typically induced within five to ten minutes of stimulation, and was performed using Affymetrix GeneChip Mouse Gene 1.0 ST Arrays. RNA profiling revealed a largely new set of differentially expressed primary response genes between the conditions acute stress and control that differed distinctly between wild-type and knockout mice. Consequently, functional categorization and pathway analysis indicated genes related to neuroplasticity and adaptation in wild-types whereas knockouts were characterized by impaired plasticity and genes more related to chronic stress and pathophysiology. Our study therefore disclosed different coping styles dependent on serotonin transporter genotype even directly after the onset of stress and accentuates the role of the serotonergic system in processing stressors and threat in the amygdala. Moreover, several of the first wave primary response genes that we found might provide promising targets for future therapeutic interventions of stress-related disorders also in humans.     

Variations of Some Physiological and Immunological Parameters in Siberian Sturgeon (Acipenser baerii,Brandt, 1869) Subjected to an Acute Stressor

This study was carried out to investigate the effect of an acute stressor on the variation of some physiological and immunological parameters of Siberian sturgeon (Acipenser baerii) juveniles. Fish, reared in 3 tanks for 10 weeks, were used for this study. The acute stress of fish consisted of 2 min of air exposure stress. Plasma levels of cortisol, glucose, and lactate as well as lysozyme activity in plasma were measured before stress and 1 hr, 3 hr, 6 hr, 9 hr, 12 hr, and 24 hr after stress. The plasma cortisol significantly increased in the highest level 1 hr after stress, yet it gradually declined after 3 hr. The glucose significantly increased only 1 hr after stress. There was no significant difference between plasma lactate prestress and poststress. Moreover, lysozyme activity was enhanced by stress, thus reaching the highest level 9 hr after stress. The results of this study indicate that Siberian sturgeon not only have a rapid response to acute stress, but also a great capacity for recovery from stress, thus returning physiological parameters to prestress levels after 6 hr.     

Selective Inhibition of Acetylcholinesterase in the Cerebellum and Hippocampus of Mice Following an Acute Treatment with Malathion

Adult male ICR mice were treated by intraperitoneal injection with 250?mg/kg of bodyweight of commercial malathion (a dose corresponding to 1/12 the LD50). After 6?h, acetylcholinesterase (AChE) activity in blood, liver, and six brain regions was determined. A statistically significant inhibition was observed in whole blood (23%), liver (21%), and, in particular, the central nervous system; the greatest degree of AChE inhibition was observed in the cerebellum (45%), followed by the hippocampus (29%). There was no significant change in AChE activity in the caudate putamen, frontal cortex, midbrain, or pons medulla. These results demonstrate that the magnitude of AChE inhibition in peripheral tissues does not accurately reflect the central-inhibitory effects of malathion on AChE activity in specific brain regions.     

Increased Sensitivity to Heparin Following Acute Myocardial Infarction

In vivo increased sensitivity to heparin has been demonstrated in patients following an acute myocardial infarction. An intravenous injection of 10,000 units of heparin was given to each of 18 patients with recent myocardial infarction in order to compare them with 17 patients who were not suffering from any acute illness. The changes in whole blood clotting time, recalcified plasma clotting time and prothrombin time were greater and more prolonged in the patients with recent myocardial infarction. Of the three tests, the one-stage prothrombin time provided the simplest and the most precise measurement of heparin sensitivity. The reason for this was not clear: it is possible that it is related to shock and congestive heart failure which were complications of the clinical course following myocardial infarction.