Effects of Acute Stress or Centrally Injected Interleukin-1beta on Neuropeptide Expression in the Immune System

Acute stress stimulates the expression and release of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus, and the pro-opiomelanocortin products beta-endorphin and ACTH from the anterior pituitary. These neuropeptides are also expressed in immune tissues, and it has been proposed that they may modulate immune responses to stress through paracrine mechanisms. We subjected rats to restraint stress or central injection of interleukin (IL)-1beta to determine whether these acute stimuli can alter the expression of neuropeptides in the spleen and thymus. Restraint stress significantly increased the contents of all these neuropeptides in thymic, but not splenic, extracts. A single icv injection of IL-1beta increased contents of CRH, AVP, ACTH and beta-endorphin in the spleens of both sham-operated and adrenalectomised (ADX) rats. IL-1beta increased thymic contents of CRH and ACTH in sham-operated rats but these increases were not observed in ADX rats. These results suggest that the effects of IL-1beta on neuropeptide expression in the spleen are independent of glucocorticoids, whereas IL-1beta stimulation of neuropeptide expression in the thymus is dependent on circulating glucocorticoids. There were significant correlations between increases in CRH, ACTH and beta-endorphin in the spleen, and between CRH and ACTH in the thymus, consistent with the suggestion that IL-1beta-induced increases in ACTH and beta-endorphin may be mediated through CRH. These results provide evidence that stressors can directly influence neuropeptide expression in immune tissues. Thus stress may influence immune functions through paracrine mechanisms involving locally synthesised neuropeptides as well as through activation of the hypothalamo-pituitary-adrenal axis.     

Implicit depression and hopelessness in remitted depressed individuals

Cognitive theories of depression posit that automatically activated cognitive schemas, including negative thoughts about the self and the future, predispose individuals to develop depressive disorders. However, prior research has largely examined these constructs using explicit tests in currently depressed individuals. Using the Implicit Association Test (IAT), the present study examined automatic associations between the self and mood state ("depression IAT") and between the future and mood state ("hopelessness IAT") before and after a negative mood induction in 19 remitted depressed individuals and 23 healthy controls. In the depression IAT, remitted depressed participants exhibited an overall lower tendency to associate themselves with happiness relative to the healthy controls before the mood induction. Control, but not remitted depressed, participants' automatic associations between the self and happiness diminished following the mood induction. Contrary to our hypotheses, no significant findings emerged when considering the hopelessness IAT. Consistent with prior studies, no significant correlations emerged between implicit and explicit biases, suggesting that these measures probe different processes. Results extend prior IAT research by documenting the presence of a reduced tendency to associate the self with happiness in a sample at increased risk for depression.     

A preliminary investigation of cognitive flexibility for emotional information in major depressive disorder and non-psychiatric controls

Clinical research suggests that individuals with major depressive disorder (MDD) are cognitively inflexible, exhibiting ruminative, rigid, and automatic thoughts within a negative schema. However, existing neuropsychological research on cognitive flexibility in this population has not employed emotional stimuli. Because research suggests that the performance of individuals with MDD is modulated when emotional stimuli are used, this study investigates the impact of emotional stimuli on cognitive flexibility performance through a novel emotional modification of the Wisconsin Card Sorting Test. Controls were less flexible when stimuli were positive and individuals with MDD were less flexible when stimuli were negative relative to the controls. These divergent styles of responding to emotional information may contribute to the relative risk or protection from depressed mood.     

Memory of faces: a slow wave ERP study of major depression

This study examined slow wave (SW) event-related brain potential (ERP) amplitudes in response to happy, neutral, and sad faces during a working memory task to further identify the associated component processes and physiological changes of mood-congruent memory biases in individuals with and without major depression. The results suggest that individuals with and without a diagnosis of major depressive disorder (MDD) differentially maintain valenced facial information in their working memory. Specifically, the nondepressed individuals displayed a marked reduction in SW amplitude to the negative faces. Individuals with MDD exhibited equivalent SW amplitudes for positive and negative facial stimuli. Results are discussed in terms of avoidance coping, previous ERP studies of working memory, and facial recognition deficits in individuals with MDD.     

Hypothalamo-Pituitary-Adrenocortical Regulation Following Lesions of the Central Nucleus of the Amygdala

Previous reports indicate that the central nucleus of the amygdala (CeA) stimulates adrenocorticotropin and corticosterone secretion, suggesting a role for this region in central hypothalamo-pituitary-adrenocortical (HPA) stress regulation. To evaluate this hypothesis, this study assessed the impact of CeA lesion on the response of hypophysiotrophic paraventricular nucleus (PVN) neurons to acute restraint and chronic unpredictable stress exposure. In contrast to previous reports, CeA lesions did not affect corticosterone or ACTH secretion induced by acute stress. Acute restraint increased PVN corticotropin releasing hormone (CRH) mRNA expression, increased the number of parvocellular PVN neurons expressing the co-secretagogue arginine vasopressin (AVP), and induced cFOS mRNA expression in the parvocellular PVN. However, there was no additional effect of CeA lesion on any measure of PVN activation. Chronic unpredictable stress exposure induced long-term activation of the HPA axis, noted by thymic involution, adrenal hypertrophy and increased PVN CRH mRNA expression. Stress-induced changes in thymus and adrenal weights were not affected by CeA lesion. Further, CeA lesion rats did not differ from controls in post-stress CRH mRNA expression. However, basal CRH mRNA expression was increased in the PVN of CeA rats, suggesting that the CeA plays a role in long-term inhibition of the PVN. The results of these studies are not consistent with the hypothesis that the CeA is necessary for stress-induced pituitary-adrenocortical activation. Rather, this region may play a stressor-specific modulatory role in regulation of HPA function.     

A slow wave investigation of working memory biases in mood disorders

Mood-congruent working memory biases were examined in a delayed matching to sample paradigm using the slow wave (SW) event-related brain potential (ERP) component. Mood-congruent working memory biases, indexed by SW amplitudes, were demonstrated among individuals experiencing a major depressive episode (MDE) and nondepressed controls but not individuals with dysthymia. However, analyses of symptom severity demonstrated that those with dysthymia exhibited significantly less negative SW amplitudes with increasing depressive mood severity, whereas individuals with major depression demonstrated more negative SW amplitudes with increasing depressive mood severity. These results are discussed in the context of diagnostic specificity for cognitive biases associated with working memory of mood-disordered individuals.     

Toward Forgiveness: The Role of Shame,Guilt Anger,and Empathy

This research explored forgiving and its relationship to adaptive moral emotional processes: proneness to shame, guilt, anger, and empathic responsiveness. Gender differences associated with forgiving were analyzed. Participants were 138 graduate students in a large northeastern urban university. Results revealed that guilt‐proneness was positively related to Total Forgiveness, as were Empathetic Concern and Perspective Taking. A positive relationship between anger reduction and Overall Forgiveness was found. Guilt‐proneness, anger reduction, and detachment informed the process of forgiveness for women. For men, age, shame‐proneness, and pride in behavior informed the process of forgiveness. Implications and possible research are discussed.