|
| ||
|
|
||
Chronic Stress (chronic + stress)
Selected AbstractsThe Medial Amygdala Modulates Body Weight but not Neuroendocrine Responses to Chronic StressJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2010M. B. Solomon Stress pathologies such as depression and eating disorders (i.e. anorexia nervosa) are associated with amygdalar dysfunction, which are linked with hypothalamic-pituitary-adrenal axis (HPA) axis hyperactivity. The medial amygdaloid nucleus (MeA), a key output nucleus of the amygdaloid complex, promotes HPA axis activation to acute psychogenic stress and is in a prime position to mediate the deleterious effects of chronic stress on physiology and behaviour. The present study tests the hypothesis that the MeA is necessary for the development of maladaptive physiological changes caused by prolonged stress exposure. Male rats received bilateral ibotenate or sham lesions targeting the MeA and one half underwent 2 weeks of chronic variable stress (CVS) or served as home cage controls. Sixteen hours post CVS, all animals were exposed to an acute restraint challenge. CVS induced thymic involution, adrenal hypertrophy, and attenuated body weight gain and up-regulation of hypothalamic corticotrophin-releasing hormone mRNA expression. Consistent with previous literature, lesions of the MeA dampened stress-induced increases in corticosterone after 30 min of exposure to acute restraint stress. However, this effect was independent of CVS exposure, suggesting that the MeA may not be critical for modulating neuroendocrine responses after chronic HPA axis drive. Interestingly, lesion of the MeA modestly exaggerated the stress-induced attenuation of weight gain. Overall, the data obtained suggest that the MeA modulates the neuroendocrine responses to acute but not chronic stress. In addition, the data suggest that the MeA may be an important neural component for the control of body weight in the face of chronic stress. [source] Effect of Chronic Stress and Mifepristone Treatment on Voltage-Dependent Ca2+ Currents in Rat Hippocampal Dentate GyrusJOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2006N. G. Van Gemert Chronic unpredictable stress affects many properties in rat brain. In the dentate gyrus, among other things, increased mRNA expression of the Ca2+ channel ,1C subunit has been found after 21 days of unpredictable stress in combination with acute corticosterone application (100 nM). In the present study, we examined: (i) whether these changes in expression are accompanied by altered Ca2+ currents in rat dentate granule cells recorded on day 22 and (ii) whether treatment with the glucocorticoid receptor antagonist mifepristone during the last 4 days of the stress protocol normalises the putative stress-induced effects. Three weeks of unpredictable stress did not affect Ca2+ current amplitude in dentate granule cells under basal conditions (i.e. after incubation with vehicle solution). However, the sustained Ca2+ current component (which largely depends on the ,1C subunit) was significantly increased in amplitude after chronic stress when slices had been treated with corticosterone 1,4 h before recording. These findings suggest that dentate granule cells are exposed to an increased calcium load after exposure to an acute stressor when they have a history of chronic stress, potentially leading to increased vulnerability of the cells. The present results are in line with the molecular data on Ca2+ channel ,1C subunit expression. A significant three-way interaction between chronic stress, corticosterone application and mifepristone treatment was found, indicating that the combined effect of stress and corticosterone depends on mifepristone cotreatment. Interestingly, current density (defined as total current divided by capacitance) did not differ between the groups. This indicates that the observed changes in Ca2+ current amplitude could be attributable to changes in cell size. [source] Chronic Pain, Chronic Stress and Depression: Coincidence or Consequence?JOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2001G. Blackburn-Munro Abstract Chronic pain and depressive illness are debilitating disease states that are variably resistant to currently available therapeutic agents. Animal models of chronic pain are associated with activation of the hypothalamo-pituitary-adrenal (HPA) axis, upon which chronic pain acts as an inescapable stressor. Inescapable stress is also associated with ,depressive-like' symptoms in experimental animals. Based on reports of the comorbidity between chronic pain and depressive illness in human patients, it is possible that these disease states are linked, via chronic stress-induced HPA dysfunction. Here, we discuss the possible involvement of the HPA axis in the aetiology of both chronic pain and clinical depression, and suggest a strategy for the development of novel pharmacotherapies. [source] Chronic Stress, Sense of Belonging, and Depression Among Survivors of Traumatic Brain InjuryJOURNAL OF NURSING SCHOLARSHIP, Issue 3 2002Esther Bay Purpose: To test whether chronic stress, interpersonal relatedness, and cognitive burden could explain depression after traumatic brain injury (TBI). Design: A nonprobability sample of 75 mild-to-moderately injured TBI survivors and their significant others, were recruited from five TBI day-rehabilitation programs. All participants were within 2 years of the date of injury and were living in the community. Methods: During face-to-face interviews, demographic information, and estimates of brain injury severity were obtained and participants completed a cognitive battery of tests of directed attention and short-term memory, responses to the Perceived Stress Scale, Interpersonal Relatedness Inventory, Sense of Belonging Instrument, Neurobehavioral Functioning Inventory, and Center for Epidemiological Studies Depression Scale;. Findings: Chronic stress was significantly and positively related to post-TBI depression. Depression and postinjury sense of belonging were negatively related. Social support and results from the cognitive battery did not explain depression. Conclusions: Postinjury chronic stress and sense of belonging were strong predictors of post-injury depression and are variables amenable to interventions by nurses in community health, neurological centers, or rehabilitation clinics. Future studies are needed to examine how these variables change over time during the recovery process. [source] Rapid reversal of stress induced loss of synapses in CA3 of rat hippocampus following water maze trainingEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2003Carmen Sandi Abstract The impact was examined of exposing rats to two life experiences of a very different nature (stress and learning) on synaptic structures in hippocampal area CA3. Rats were subjected to either (i) chronic restraint stress for 21 days, and/or (ii) spatial training in a Morris water maze. At the behavioural level, restraint stress induced an impairment of acquisition of the spatial response. Moreover, restraint stress and water maze training had contrasting impacts on CA3 synaptic morphometry. Chronic stress induced a loss of simple asymmetric synapses [those with an unperforated postsynaptic density (PSD)], whilst water maze learning reversed this effect, promoting a rapid recovery of stress-induced synaptic loss within 2,3 days following stress. In addition, in unstressed animals a correlation was found between learning efficiency and the density of synapses with an unperforated PSD: the better the performance in the water maze, the lower the synaptic density. Water maze training increased the number of perforated synapses (those with a segmented PSD) in CA3, both in stressed and, more notably, in unstressed rats. The distinct effects of stress and learning on CA3 synapses reported here provide a neuroanatomical basis for the reported divergent effects of these experiences on hippocampal synaptic activity, i.e. stress as a suppressor and learning as a promoter of synaptic plasticity. [source] From ancient genes to modern communities: the cellular stress response and the evolution of plant strategiesFUNCTIONAL ECOLOGY, Issue 5 2005S. PIERCE Summary 1Two major plant strategy theories attempt to explain how phenotype determines community structure. Crucially, CSR plant strategy theory suggests that stress and sporadic resource availability favour conservative phenotypes, whereas the resource-ratio hypothesis views the spatial heterogeneity of resources as selecting for optimal foraging in chronically unproductive habitats. Which view is most realistic? 2The ecophysiology literature demonstrates that stress is comprised of two processes: (1) limitation of resource supply to metabolism; and (2) damage to biomembranes, proteins and genetic material (chronic stress). Thus stress is defined mechanistically as the suboptimal performance of metabolism. 3Adaptations to limitation buffer metabolism against variability in external resource supply; internal storage pools are more consistent. Chronic stress elicits the same ancient cellular stress response in all cellular life: investment in stress metabolites that preserve the integrity and compartmentalization of metabolic components in concert with molecular damage-repair mechanisms. 4The cellular stress response was augmented by morphological innovations during the Silurian,Devonian terrestrial radiation, during which nutrient limitation appears to have been a principal selection pressure (sensu CSR theory). 5The modern stress,tolerator syndrome is conservative and supports metabolism in limiting or fluctuating environmental conditions: standing resource pools with high investment/maintenance costs impose high internal diffusion resistances and limit inherent growth rate (sensu CSR theory). 6The resource-ratio hypothesis cannot account for the cellular stress response or the crucial role of ombrotrophy in primary succession. CSR theory agrees with current understanding of the cellular stress response, terrestrial radiation and modern adaptations recorded in chronically unproductive habitats, and is applicable as CSR classification. [source] Conserved cellular function and stress-mediated regulation among members of the proteolipid protein familyJOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2010María E. Fernández Abstract Chronic stress causes morphological alterations in the hippocampus of rodents and tree shrews, including atrophy of CA3 dendrites and loss of synapses. The molecular mechanisms underlying these structural changes remain largely unknown. We have previously identified M6a as a stress responsive gene and shown that M6a is involved in filopodium/spine outgrowth and, likely, synapse formation. M6a belongs to the proteolipid protein (PLP) family, all of their members having four transmembrane domains that allow their localization at the plasma membrane. In the present work, we analyzed other members of this family, the closely related M6b as well as PLP and its splice variant DM20. We found that chronic restraint stress in mice reduces M6b and DM20, but not PLP, mRNA levels in the hippocampus. In addition, M6b and DM20, but again not PLP, induce filopodium formation in primary cultures of hippocampal neurons. Several M6b protein isoforms were studied, all of them having similar effects except for the one lacking the transmembrane domains. Our results reveal a conserved cellular function and a stress-mediated regulation among members of the proteolipid protein family, suggesting an involvement of proteolipid proteins in the stress response. © 2009 Wiley-Liss, Inc. [source] Chronic Stress, Sense of Belonging, and Depression Among Survivors of Traumatic Brain InjuryJOURNAL OF NURSING SCHOLARSHIP, Issue 3 2002Esther Bay Purpose: To test whether chronic stress, interpersonal relatedness, and cognitive burden could explain depression after traumatic brain injury (TBI). Design: A nonprobability sample of 75 mild-to-moderately injured TBI survivors and their significant others, were recruited from five TBI day-rehabilitation programs. All participants were within 2 years of the date of injury and were living in the community. Methods: During face-to-face interviews, demographic information, and estimates of brain injury severity were obtained and participants completed a cognitive battery of tests of directed attention and short-term memory, responses to the Perceived Stress Scale, Interpersonal Relatedness Inventory, Sense of Belonging Instrument, Neurobehavioral Functioning Inventory, and Center for Epidemiological Studies Depression Scale;. Findings: Chronic stress was significantly and positively related to post-TBI depression. Depression and postinjury sense of belonging were negatively related. Social support and results from the cognitive battery did not explain depression. Conclusions: Postinjury chronic stress and sense of belonging were strong predictors of post-injury depression and are variables amenable to interventions by nurses in community health, neurological centers, or rehabilitation clinics. Future studies are needed to examine how these variables change over time during the recovery process. [source] Social stress, visceral obesity, and coronary artery atherosclerosis: product of a primate adaptationAMERICAN JOURNAL OF PRIMATOLOGY, Issue 9 2009Carol A. Shively Abstract Abdominal obesity is prevalent and often accompanied by an array of metabolic perturbations including elevated blood pressure, dyslipidemia, impaired glucose tolerance or insulin resistance, a prothrombotic state, and a proinflammatory state, together referred to as the metabolic syndrome. The metabolic syndrome greatly increases coronary heart disease (CHD) risk. Social stress also increases CHD although the mechanisms through which this occurs are not completely understood. Chronic stress may result in sustained glucocorticoid production, which is thought to promote visceral obesity. Thus, one hypothesis is that social stress may cause visceral fat deposition and the metabolic syndrome, which, in turn increases CHD. CHD is caused by coronary artery atherosclerosis (CAA) and its sequelae. Cynomolgus monkeys (Macaca fascicularis) are a well-established models of CAA. Social subordination may be stressful to cynomolgus monkeys and result in hypercortisolemia and exacerbated CAA in females. Herein is reviewed a body of literature which suggests that social stress increases visceral fat deposition in cynomolgus monkeys, that subordinate females are more likely than dominants to have visceral obesity, that females with visceral obesity have behavioral and physiological characteristics consistent with a stressed state, and that females with high ratios of visceral to subcutaneous abdominal fat develop more CAA. While these relationships have been most extensively studied in cynomolgus macaques, obesity-related metabolic disturbances are also observed in other primate species. Taken together, these observations support the view that the current obesity epidemic is the result of a primate adaptation involving the coevolution with encephalization of elaborate physiological systems to protect against starvation and defend stored body fat in order to feed a large and metabolically demanding brain. Social stress may be engaging these same physiological systems, increasing the visceral deposition of fat and its sequelae, which increase CHD risk. Am. J. Primatol. 71:742,751, 2009. © 2009 Wiley-Liss, Inc. [source] Comparison of stress responses in wild and captive winter flounder (Pseudopleuronectes americanus Walbaum) broodstockAQUACULTURE RESEARCH, Issue 10 2003S Plante Abstract Chronic stress is responsible for many problems occurring in fish holding facilities, such as increased susceptibility to disease, reduced growth rate and suppression of the immune response. The goal of this study was to verify if wild winter flounder (Pseudopleuronectes americanus Walbaum) suffer from chronic stress when kept several months in captivity. We hypothesized that winter flounder not subjected to chronic stress in captivity would have similar or higher condition indices and similar stress response compared to fish from the wild. Our results showed that the condition index of winter flounder kept in captivity was higher (1.50) than those from the wild (1.33) even after one year of captivity. The intensity of the acute stress response following short-term exposure to air was similar between wild and captive fish (no significant interaction between the factors ,stress' and ,origin of the fish'). Body water content (an indicator of energy reserves) was lower (76.1%) compared to wild fish (79.8%) after one year of captivity, suggesting that the winter fast had been less energetically demanding in captive fish. These results indicate that no chronic stress was present in captive fish. On the other hand, the mortality during captivity was around 30%, which is high for the aquaculture industry. Further work to address this problem is required. [source] Filopodial protrusions induced by glycoprotein M6a exhibit high motility and aids synapse formationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2010Marcela A. Brocco Abstract M6a is a neuronal membrane glycoprotein whose expression diminishes during chronic stress. M6a overexpression in rat primary hippocampal neurons induces the formation of filopodial protrusions that could be spine precursors. As the filopodium and spine motility has been associated with synaptogenesis, we analysed the motility of M6a-induced protrusions by time-lapse imaging. Our data demonstrate that the motile protrusions formed by the neurons overexpressing M6a were more abundant and moved faster than those formed in control cells. When different putative M6a phosphorylation sites were mutated, the neurons transfected with a mutant lacking intracellular phosphorylation sites bore filopodia, but these protrusions did not move as fast as those formed by cells overexpressing wild-type M6a. This suggests a role for M6a phosphorylation state in filopodium motility. Furthermore, we show that M6a-induced protrusions could be stabilized upon contact with presynaptic region. The motility of filopodia contacting or not neurites overexpressing synaptophysin was analysed. We show that the protrusions that apparently contacted synaptophysin-labeled cells exhibited less motility. The behavior of filopodia from M6a-overexpressing cells and control cells was alike. Thus, M6a-induced protrusions may be spine precursors that move to reach presynaptic membrane. We suggest that M6a is a key molecule for spine formation during development. [source] ,2A and ,2C -adrenoceptor regulation in the brain: ,2A changes persist after chronic stressEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2003G. Flügge Abstract Stress-induced activation of the central nervous noradrenergic system has been suspected to induce depressive disorders. As episodes of depression often occur some time after a stress experience we investigated whether stress-induced changes in the ,2 -adrenoceptor (,2 -AR) system persist throughout a post-stress recovery period. Brains of male tree shrews were analysed after 44 days of chronic psychosocial stress and after a subsequent 10-day recovery period. Expression of RNA for ,2A and ,2C -adrenoceptors was quantified by in situ hybridization, and receptor binding was determined by in vitro receptor autoradiography. Activities of the sympathetic nervous system and of the hypothalamo,pituitary,adrenal axis were increased during chronic stress but normalized during recovery. ,2A -AR RNA in the glutamatergic neurons of the lateral reticular nucleus was elevated significantly after stress and after recovery (by 29% and 17%). In the dorsal motor nucleus of the vagus, subtype A expression was enhanced after recovery (by 33%). In the locus coeruleus, subtype A autoreceptor expression was not changed significantly. Subtype C expression in the caudate nucleus and putamen was elevated by stress (by 5 and 4%, respectively) but normalized during recovery. Quantification of 3H-RX821002 binding revealed receptor upregulation during stress and/or recovery. Our data therefore show: (i) that chronic psychosocial stress differentially regulates expression of ,2 -adrenoceptor subtypes A and C; (ii) that subtype A heteroreceptor expression is persistently upregulated whereas (iii), subtype C upregulation is only transient. The present findings coincide with post mortem studies in depressed patients revealing upregulation of ,2A -ARs. [source] Repeated restraint stress suppresses neurogenesis and induces biphasic PSA-NCAM expression in the adult rat dentate gyrusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2003Kara Pham Abstract Chronic restraint stress has been shown to induce structural remodelling throughout the interconnected dentate gyrus-CA3 fields. To find out how this stressor affects the rate of adult hippocampal neurogenesis, we subjected rats to acute or chronic restraint stress and assessed the proliferation, survival and differentiation of newly born cells in the dentate gyrus. We also examined polysialylated neural cell adhesion molecule expression, a molecule normally expressed in immature neurons and important for morphological plasticity. The results show that acute restraint stress did not change either the proliferation of dentate gyrus precursor cells or the expression of polysialylated neural cell adhesion molecule, whereas 3 weeks of chronic restraint stress suppressed proliferation by 24% and increased polysialylated neural cell adhesion molecule expression by 40%. The study was extended for an additional 3 weeks to trace the survival and development of the cells born after the initial 3 weeks of restraint. Rats subjected to 6 weeks of daily restraint stress exhibited suppressed cell proliferation and attenuated survival of the recently born cells after the extended time course, resulting in a 47% reduction of granule cell neurogenesis. Furthermore, 6 weeks of chronic stress significantly reduced the total number of granule cells by 13% and the granule cell layer volume by 5%. Expression of polysialylated neural cell adhesion molecule followed a biphasic time course, displaying a significant up-regulation after 3 weeks of daily restraint stress that was lost after 6 weeks of stress. These studies may help us understand the basis for hippocampal shrinkage and raise questions about the ultimate reversibility of the effects of chronic stress. [source] Selective chronic stress-induced in vivo ERK1/2 hyperphosphorylation in medial prefrontocortical dendrites: implications for stress-related cortical pathology?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2002A. Trentani Abstract Stress has been shown to affect brain structural plasticity, promote long-term changes in multiple neurotransmitter systems and cause neuronal atrophy. However, the mechanisms involved in these stress-related neural alterations are still poorly understood. Mitogen-activated protein kinase (MAPK) cascades play a crucial role in the transduction of neurotrophic signal from the cell surface to the nucleus and are implicated in the modulation of synaptic plasticity and neuronal survival. An intriguing possibility is that stress might influence brain plasticity through its effects on selective members of such intracellular signalling cascades responsible for the transduction of neurotrophin signals. Here, we have investigated the effects of stress on the expression of three members of the MAPK/extracellular-regulated kinase (ERK) pathway such as phospho-ERK1, phospho-ERK2 and phospho-cAMP/calcium-responsive element-binding protein (CREB) in the adult rat brain. Male rats were subjected to mild footshocks and the patterns of protein expression were analysed after 21 consecutive days of stress. We found that chronic stress induced a pronounced and persistent ERK1/2 hyperphosphorylation in dendrites of the higher prefrontocortical layers (II and III) and a reduction of phospho-CREB expression in several cortical and subcortical regions. We hypothesized that defects in ERK signalling regulation combined with a reduced phospho-CREB activity may be a crucial mechanism by which sustained stress may induce atrophy of selective subpopulations of vulnerable cortical neurons and/or distal dendrites. Thus, ERK-mediated cortical abnormalities may represent a specific path by which chronic stress affects the functioning of cortical structures and causes selective neural network defects. [source] From ancient genes to modern communities: the cellular stress response and the evolution of plant strategiesFUNCTIONAL ECOLOGY, Issue 5 2005S. PIERCE Summary 1Two major plant strategy theories attempt to explain how phenotype determines community structure. Crucially, CSR plant strategy theory suggests that stress and sporadic resource availability favour conservative phenotypes, whereas the resource-ratio hypothesis views the spatial heterogeneity of resources as selecting for optimal foraging in chronically unproductive habitats. Which view is most realistic? 2The ecophysiology literature demonstrates that stress is comprised of two processes: (1) limitation of resource supply to metabolism; and (2) damage to biomembranes, proteins and genetic material (chronic stress). Thus stress is defined mechanistically as the suboptimal performance of metabolism. 3Adaptations to limitation buffer metabolism against variability in external resource supply; internal storage pools are more consistent. Chronic stress elicits the same ancient cellular stress response in all cellular life: investment in stress metabolites that preserve the integrity and compartmentalization of metabolic components in concert with molecular damage-repair mechanisms. 4The cellular stress response was augmented by morphological innovations during the Silurian,Devonian terrestrial radiation, during which nutrient limitation appears to have been a principal selection pressure (sensu CSR theory). 5The modern stress,tolerator syndrome is conservative and supports metabolism in limiting or fluctuating environmental conditions: standing resource pools with high investment/maintenance costs impose high internal diffusion resistances and limit inherent growth rate (sensu CSR theory). 6The resource-ratio hypothesis cannot account for the cellular stress response or the crucial role of ombrotrophy in primary succession. CSR theory agrees with current understanding of the cellular stress response, terrestrial radiation and modern adaptations recorded in chronically unproductive habitats, and is applicable as CSR classification. [source] Changes in adipocytes and dendritic cells in lymph node containing adipose depots during and after many weeks of mild inflammationJOURNAL OF ANATOMY, Issue 6 2005Dawn Sadler Abstract The time course and cellular basis for inflammation-induced hypertrophy of adipose tissue were investigated over 20 weeks in mature male rats. Mild inflammation was induced by subcutaneous injection of 20 µg lipopolysaccharide into one hind-leg three times/week for 4 or 8 weeks, followed by up to 12 weeks ,rest' without intervention. Mean volume and frequency of apoptosis (TUNEL assay) were measured in adipocytes isolated from sites defined by their anatomical relations to lymph nodes, plus numbers of CCL21-stimulated lymph node-derived and adipose tissue-derived dendritic cells. Experimental inflammation increased dendritic cells and adipocyte apoptosis in the locally stimulated popliteal depot and the lymphoid tissue-associated regions of the contralateral popliteal and mesentery and omentum. Responses declined slowly after inflammation ended, but all measurements from the locally stimulated popliteal depot, and the omentum, were still significantly different from controls after 12 weeks rest. The locally stimulated popliteal adipose tissue enlarged by 5% within 4 weeks and remained larger than the control. We conclude that prolonged inflammation induces permanent enlargement, greater adipocyte turnover and increased dendritic cell surveillance in the adjacent adipose tissue and the omentum. The experiment suggests a mechanism for selective hypertrophy of lymphoid tissue-associated adipose tissue in chronic stress and inflammatory disorders, including impaired lymph drainage, Crohn's disease and HIV-associated lipodystrophy, and a link between evolutionary fitness, sexual selection and aesthetically pleasing body symmetry. It would be useful for further study of molecular mechanisms in inflammation-induced local hypertrophy of adipose tissue and development of specific therapies that avoid interference with whole-body lipid metabolism. [source] Problem solving moderates the effects of life event stress and chronic stress on suicidal behaviors in adolescenceJOURNAL OF CLINICAL PSYCHOLOGY, Issue 12 2009Kelly E. Grover Abstract The present study examined the unique and interactive effects of stress and problem-solving skills on suicidal behaviors among 102 inpatient adolescents. As expected, life event stress and chronic stress each significantly predicted suicidal ideation and suicide attempt. Problem solving significantly predicted suicidal ideation, but not suicide attempt. Problem solving moderated the associations between life event stress and suicidal behaviors, as well as between chronic stress and suicidal ideation, but not chronic stress and suicide attempt. At high levels of stress, adolescents with poor problem-solving skills experienced elevated suicidal ideation and were at greater risk of making a nonfatal suicide attempt. The interactive effects decreased to non-significance after controlling for depressive symptoms and hopelessness. Clinical implications are discussed.© 2009 Wiley Periodicals, Inc. J Clin Psychol 65:1,10, 2009. [source] The Medial Amygdala Modulates Body Weight but not Neuroendocrine Responses to Chronic StressJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2010M. B. Solomon Stress pathologies such as depression and eating disorders (i.e. anorexia nervosa) are associated with amygdalar dysfunction, which are linked with hypothalamic-pituitary-adrenal axis (HPA) axis hyperactivity. The medial amygdaloid nucleus (MeA), a key output nucleus of the amygdaloid complex, promotes HPA axis activation to acute psychogenic stress and is in a prime position to mediate the deleterious effects of chronic stress on physiology and behaviour. The present study tests the hypothesis that the MeA is necessary for the development of maladaptive physiological changes caused by prolonged stress exposure. Male rats received bilateral ibotenate or sham lesions targeting the MeA and one half underwent 2 weeks of chronic variable stress (CVS) or served as home cage controls. Sixteen hours post CVS, all animals were exposed to an acute restraint challenge. CVS induced thymic involution, adrenal hypertrophy, and attenuated body weight gain and up-regulation of hypothalamic corticotrophin-releasing hormone mRNA expression. Consistent with previous literature, lesions of the MeA dampened stress-induced increases in corticosterone after 30 min of exposure to acute restraint stress. However, this effect was independent of CVS exposure, suggesting that the MeA may not be critical for modulating neuroendocrine responses after chronic HPA axis drive. Interestingly, lesion of the MeA modestly exaggerated the stress-induced attenuation of weight gain. Overall, the data obtained suggest that the MeA modulates the neuroendocrine responses to acute but not chronic stress. In addition, the data suggest that the MeA may be an important neural component for the control of body weight in the face of chronic stress. [source] Effect of Chronic Stress and Mifepristone Treatment on Voltage-Dependent Ca2+ Currents in Rat Hippocampal Dentate GyrusJOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2006N. G. Van Gemert Chronic unpredictable stress affects many properties in rat brain. In the dentate gyrus, among other things, increased mRNA expression of the Ca2+ channel ,1C subunit has been found after 21 days of unpredictable stress in combination with acute corticosterone application (100 nM). In the present study, we examined: (i) whether these changes in expression are accompanied by altered Ca2+ currents in rat dentate granule cells recorded on day 22 and (ii) whether treatment with the glucocorticoid receptor antagonist mifepristone during the last 4 days of the stress protocol normalises the putative stress-induced effects. Three weeks of unpredictable stress did not affect Ca2+ current amplitude in dentate granule cells under basal conditions (i.e. after incubation with vehicle solution). However, the sustained Ca2+ current component (which largely depends on the ,1C subunit) was significantly increased in amplitude after chronic stress when slices had been treated with corticosterone 1,4 h before recording. These findings suggest that dentate granule cells are exposed to an increased calcium load after exposure to an acute stressor when they have a history of chronic stress, potentially leading to increased vulnerability of the cells. The present results are in line with the molecular data on Ca2+ channel ,1C subunit expression. A significant three-way interaction between chronic stress, corticosterone application and mifepristone treatment was found, indicating that the combined effect of stress and corticosterone depends on mifepristone cotreatment. Interestingly, current density (defined as total current divided by capacitance) did not differ between the groups. This indicates that the observed changes in Ca2+ current amplitude could be attributable to changes in cell size. [source] Effect of Environmental Enrichment on Stress Related Systems in RatsJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2004F. Moncek Abstract The aim of this study was to test whether environmental enrichment alters the status and responsiveness of pituitary-adrenocortical and sympathetic-adrenomedullary hormones in rats. Previous studies have shown that rats kept in an enriched environment differ from those kept in standard cages in dendritic branching, synaptogenesis, memory function, emotionality and behaviour. In male Wistar rats kept in an enriched environment for 40 days, we studied basal concentrations of hormones, endocrine responses to 5-HT1A challenge and responsiveness and adaptation to repeated handling. Environmental enrichment consisted of large plexiglass cages with 10 rats per cage, which contained variety of objects exchanged three times a week. Rats kept in this enriched environment had higher resting plasma concentrations of corticosterone, larger adrenals and increased corticosterone release to buspirone challenge compared to controls. Lower adrenocorticotropic hormone, corticosterone and adrenaline responses to handling were noticed in rats kept in an enriched environment. Exposure to repeated handling led to a more rapid extinction of corticosterone responses in rats kept in an enriched environment. Thus, environmental enrichment leads to pronounced changes in neuroendocrine regulation, including larger adrenals and increased adrenocortical function, which are so far considered to be indication of chronic stress. [source] Effects of escitalopram on the regulation of brain-derived neurotrophic factor and nerve growth factor protein levels in a rat model of chronic stressJOURNAL OF NEUROSCIENCE RESEARCH, Issue 11 2009Olaf Schulte-Herbrüggen Abstract Escitalopram (ES-CIT) is a widely used, highly specific antidepressant. Until now there has been very little evidence on how this drug under pathological conditions affects an important feature within the pathophysiology of stress-related disorders such as depression: the endogenous neurotrophins. By using a well-characterized rat model in which chronic stress induces depressive-like behavior, the levels of neurotrophins brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were determined in representative brain regions and serum using a highly sensitive improved fluorometric two-site ELISA system. There was a significant increase of BDNF in the left and right cortices after stress treatment (twofold increase) that was reversed by application of ES-CIT. An ES-CIT-dependent NGF reduction in stressed rats was detectable in the right cortex only (P = 0.027). The left hippocampus revealed significantly higher amounts of BDNF (2.5-fold increase) protein than the right hippocampus. These interhemispheric differences were unrelated to stress or ES-CIT treatment in all animals. BDNF and NGF of the frontal cortex, cerebellum, and serum did not change between the study groups. There was a negative correlation between body weight and serum BDNF, independent of stress or ES-CIT treatment. In conclusion, BDNF and NGF show substantial changes in this rodent model of chronic social stress, which is susceptible to antidepressant treatment with ES-CIT and therefore may constitute a neurobiological correlate for the disease. © 2009 Wiley-Liss, Inc. [source] Chronic Stress, Sense of Belonging, and Depression Among Survivors of Traumatic Brain InjuryJOURNAL OF NURSING SCHOLARSHIP, Issue 3 2002Esther Bay Purpose: To test whether chronic stress, interpersonal relatedness, and cognitive burden could explain depression after traumatic brain injury (TBI). Design: A nonprobability sample of 75 mild-to-moderately injured TBI survivors and their significant others, were recruited from five TBI day-rehabilitation programs. All participants were within 2 years of the date of injury and were living in the community. Methods: During face-to-face interviews, demographic information, and estimates of brain injury severity were obtained and participants completed a cognitive battery of tests of directed attention and short-term memory, responses to the Perceived Stress Scale, Interpersonal Relatedness Inventory, Sense of Belonging Instrument, Neurobehavioral Functioning Inventory, and Center for Epidemiological Studies Depression Scale;. Findings: Chronic stress was significantly and positively related to post-TBI depression. Depression and postinjury sense of belonging were negatively related. Social support and results from the cognitive battery did not explain depression. Conclusions: Postinjury chronic stress and sense of belonging were strong predictors of post-injury depression and are variables amenable to interventions by nurses in community health, neurological centers, or rehabilitation clinics. Future studies are needed to examine how these variables change over time during the recovery process. [source] The Effects of Ethanol Consumption on Vasculogenesis Potential in Nonhuman PrimatesALCOHOLISM, Issue 1 2008J. Koudy Williams Background:, Vasculogenesis is essential to the preservation and repair of damaged or diseased vessels. Alcohol is the most commonly abused drug among young adults, but its effects on vessel growth and repair are unknown. The basis of vascular repair is endothelial progenitor cell (EPC) recruitment to assist in the formation of new vascular network (vasculogenesis). Therefore, the objective of this study was to measure the effects of ethanol consumption on the production, mobilization and vasculogenesis potential EPCs in nonhuman primates. Methods:, Four to five year-old (young adult) male rhesus monkeys consumed monkey chow and water (Control, n = 7), or chow and water + ethanol (Alcohol, 2.45 g/d, n = 7) for 12 months. Peripheral blood (PB) and bone marrow (BM) samples were collected for fluorescence-activated cell-sorting analysis of cell surface antigens (CD45, CD31, CD44, CD133, VEGF-R2 , or KDR); and for capillary formation on Matrigel-coated plates. Results:, There were greater numbers of nonhematopoeitic stromal cells (CD45,) and putative mesenchymal progenitor cells (CD45,/CD44+) in the PB and BM of Alcohol versus Control monkeys (p < 0.05). Additionally, there were greater numbers of EPCs (CD45,/CD133+/KDR+) in the BM and PB of Alcohol versus Control monkeys (p < 0.05). However, the EPCs of Alcohol monkeys were less likely to form capillaries on matrigel-coated plates than Control monkeys (p < 0.05). Conclusions:, Ethanol consumption in monkeys markedly increased the production and mobilization of EPCs, but decreased their ability to form capillaries. The pathophysiologic consequences of such effects are unclear, but may represent an ethanol-induced chronic stress on the BM, resulting in EPC. [source] Effects of psychological stress on the cerebral processing of visceral stimuli in healthy womenNEUROGASTROENTEROLOGY & MOTILITY, Issue 7 2009C. Rosenberger Abstract, The aim of the study was to analyse effects of psychological stress on the neural processing of visceral stimuli in healthy women. The brain functional magnetic resonance imaging blood oxygen level-dependent response to non-painful and painful rectal distensions was recorded from 14 healthy women during acute psychological stress and a control condition. Acute stress was induced with a modified public speaking stress paradigm. State anxiety was assessed with the State-Trait-Anxiety Inventory; chronic stress was measured with the Perceived Stress Questionnaire. During non-painful distensions, activation was observed in the right posterior insular cortex (IC) and right S1. Painful stimuli revealed activation of the bilateral anterior IC, right S1, and right pregenual anterior cingulate cortex. Chronic stress score was correlated with activation of the bilateral amygdala, right posterior IC (post-IC), left periaqueductal grey (PAG), and right dorsal posterior cingulate gyrus (dPCC) during non-painful stimulation, and with activation of the right post-IC, right PAG, left thalamus (THA), and right dPCC during painful distensions. During acute stress, state anxiety was significantly higher and the acute stress , control contrast revealed activation of the right dPCC, left THA and right S1 during painful stimulation. This is the first study to demonstrate effects of acute stress on cerebral activation patterns during visceral pain in healthy women. Together with our finding that chronic stress was correlated wit the neural response to visceral stimuli, these results provide a framework for further studies addressing the role of chronic stress and emotional disturbances in the pathophysiology of visceral hyperalgesia. [source] Stress-Induced Drinking in Parents of Adolescents with Externalizing Symptomatology: The Moderating Role of Parent Social SupportTHE AMERICAN JOURNAL ON ADDICTIONS, Issue 6 2008Elizabeth D. Handley MA Parenting adolescents with externalizing symptomatology has been repeatedly shown to be stress-inducing for parents. One possible coping strategy for parents dealing with this chronic stress may be drinking. The current study extended previous research by examining the prospective relations between adolescents' externalizing behaviors and parents' negative affect and alcohol consumption. Additionally, the present study tested whether this mediated effect is a function of parental social support. Adolescents' externalizing symptoms prospectively predicted mothers' negative affect. Interestingly, however, mothers' negative affect prospectively predicted mothers' drinking only for those mothers with low social support. Furthermore, the mediated effect (Wave 1 adolescent externalizing symptoms , Wave 2 mother negative affect , Wave 3 mother drinking) was significant only for mothers with low social support. There were no effects of adolescents' externalizing symptoms on fathers. [source] Living together: behavior and welfare in single and mixed species groups of capuchin (Cebus apella) and squirrel monkeys (Saimiri sciureus)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2010Rebecca Leonardi Abstract There are potential advantages of housing primates in mixed species exhibits for both the visiting public and the primates themselves. If the primates naturally associate in the wild, it may be more educational and enjoyable for the public to view. Increases in social complexity and stimulation may be enriching for the primates. However, mixed species exhibits might also create welfare problems such as stress from interspecific aggression. We present data on the behavior of single and mixed species groups of capuchin monkeys (Cebus apella) and squirrel monkeys (Saimiri sciureus) housed at the Living Links to Human Evolution Research Centre in the Royal Zoological Society of Scotland's Edinburgh Zoo. These species associate in the wild, gaining foraging benefits and decreased predation. But Cebus are also predators themselves with potential risks for the smaller Saimiri. To study their living together we took scan samples at ,15,min intervals on single (n=109) and mixed species groups (n=152), and all occurrences of intraspecific aggression and interspecific interactions were recorded. We found no evidence of chronic stress and Saimiri actively chose to associate with Cebus. On 79% of scans, the two species simultaneously occupied the same part of their enclosure. No vertical displacement was observed. Interspecific interactions were common (>2.5/hr), and equally divided among mildly aggressive, neutral, and affiliative interactions such as play. Only one aggressive interaction involved physical contact and was non-injurious. Aggressive interactions were mostly (65%) displacements and vocal exchanges, initiated almost equally by Cebus and Saimiri. Modifications to the enclosure were successful in reducing these mildly aggressive interactions with affiliative interactions increasing in frequency and diversity. Our data suggest that in carefully designed, large enclosures, naturally associating monkeys are able to live harmoniously and are enriched by each other. Am. J. Primatol. 72:33,47, 2010. © 2009 Wiley-Liss, Inc. [source] Factors affecting fecal glucocorticoid levels in semi-free-ranging female mandrills (Mandrillus sphinx)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2008Joanna M Setchell Abstract Subordinate female cercopithecine primates often experience decreased reproductive success in comparison with high-ranking females, with a later age at sexual maturity and first reproduction and/or longer interbirth intervals. One explanation that has traditionally been advanced to explain this is high levels of chronic social stress in subordinates, resulting from agonistic and aggressive interactions and leading to higher basal levels of glucocorticoids. We assessed the relationships among fecal cortisol levels and reproductive condition, dominance rank, degree of social support, and fertility in female mandrills (Mandrillus sphinx) living in a semi-free-ranging colony in Franceville, Gabon. Lower-ranking females in this colony have a reproductive disadvantage relative to higher-ranking females, and we were interested in determining whether this relationship between dominance rank and reproductive success is mediated through stress hormones. We analyzed 340 fecal samples from 19 females, collected over a 14-month period. We found that pregnant females experienced higher fecal cortisol levels than cycling or lactating females. This is similar to results for other primate species and is likely owing to increased metabolic demands and interactions between the hypothalamus,pituitary,adrenal axis, estrogen, and placental production of corticotrophin releasing hormones during pregnancy. There was no influence of dominance rank on fecal cortisol levels, suggesting that subordinate females do not suffer chronic stress. This may be because female mandrills have a stable social hierarchy, with low levels of aggression and high social support. However, we found no relationship between matriline size, as a measure of social support, and fecal cortisol levels. Subordinates may be able to avoid aggression from dominants in the large enclosure or may react only transiently to specific aggressive events, rather than continuously expecting them. Finally, we found no relationship between fecal cortisol levels and fertility. There was no difference in fecal cortisol levels between conceptive and nonconceptive cycles, and no significant relationship between fecal cortisol level and either the length of postpartum amenorrhea or the number of cycles before conception. This suggests that the influence of dominance rank on female reproductive success in this population is not mediated through chronic stress in subordinate females, and that alternative explanations of the relationship between social rank and reproduction should be sought. Am. J. Primatol. 70:1023,1032, 2008. © 2008 Wiley-Liss, Inc. [source] An Exploration of the Relationship Between Depressive Symptoms and Cortisol Rhythms in Colorado RanchersTHE JOURNAL OF RURAL HEALTH, Issue 1 2009Emily Schulze MA ABSTRACT:,Context: Although the effects of stress on health have been studied in numerous urban-dwelling populations, fewer studies have addressed these effects in rural populations, such as farmers and ranchers. Purpose: The present study focuses on seasonal levels of depressed affect and perceived stress in Western Colorado ranchers, and how those phenomena related to their levels of cortisol. Methods: Twenty-one (21) ranchers, who were permittees on the Colorado Grand Mesa, completed the study. Participants identified 2-week time periods during the year representing relative high, medium, and low stress. During each period, participants took saliva samples, rated stress levels, and completed a daily health diary. In addition, the Beck Depression Inventory (BDI-II), the perceived stress scale (PSS), and a life events scale (LES) were administered. Results: Results showed a strong relationship between BDI-II and PSS scores (r = 0.748, P < .01). The decreased daytime cortisol decline supports the notion that the hypothalamic-pituitary-adrenal (HPA) axis negative feedback loop is disrupted in chronic stress and depression, thus resulting in chronically elevated cortisol levels. Conclusion: This study supports the relationship between stress, depression, and HPA dysregulation in ranchers. [source] Chronic immobilization-induced stress increases plasma testosterone and delays testicular maturation in pubertal ratsANDROLOGIA, Issue 1 2000S. A. Almeida Summary. We investigated whether chronic stress, applied from prepuberty to early puberty, interferes with the spermatogenic and androgenic testicular functions. Male pubertal rats (40 days old) were immobilized 6 h per day for 15 days. Plasma concentrations of corticosterone, prolactin and testosterone were significantly augmented following immobilization, whereas plasma luteinizing hormone decreased and follicle-stimulating hormone was not altered. Acute immobilization (5 min) increased prolactin and testosterone levels in control rats but caused a significantly higher increase in these hormones when superimposed on chronic stress. A lower extent of testicular maturation was observed in pubertal rats immobilized from prepuberty. [source] Comparison of stress responses in wild and captive winter flounder (Pseudopleuronectes americanus Walbaum) broodstockAQUACULTURE RESEARCH, Issue 10 2003S Plante Abstract Chronic stress is responsible for many problems occurring in fish holding facilities, such as increased susceptibility to disease, reduced growth rate and suppression of the immune response. The goal of this study was to verify if wild winter flounder (Pseudopleuronectes americanus Walbaum) suffer from chronic stress when kept several months in captivity. We hypothesized that winter flounder not subjected to chronic stress in captivity would have similar or higher condition indices and similar stress response compared to fish from the wild. Our results showed that the condition index of winter flounder kept in captivity was higher (1.50) than those from the wild (1.33) even after one year of captivity. The intensity of the acute stress response following short-term exposure to air was similar between wild and captive fish (no significant interaction between the factors ,stress' and ,origin of the fish'). Body water content (an indicator of energy reserves) was lower (76.1%) compared to wild fish (79.8%) after one year of captivity, suggesting that the winter fast had been less energetically demanding in captive fish. These results indicate that no chronic stress was present in captive fish. On the other hand, the mortality during captivity was around 30%, which is high for the aquaculture industry. Further work to address this problem is required. [source] | ||||||||||||||||