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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Increasing evidence suggests that depression is characterised by impaired brain plasticity that might originate from the interaction between genetic and environmental risk factors. Hence, the aim of this study was to investigate changes in neuroplasticity following exposure to stress, an environmental condition highly relevant to psychiatric disorders, in glucocorticoid receptor-deficient mice (GR(+/-)), a genetic model of predisposition to depression. Specifically, we have analysed the neurotrophin brain-derived neurotrophic factor (BDNF) and the immediate-early gene activity-regulated cytoskeletal-associated protein (Arc), two closely related molecules that can contribute to neuroplastic and morphological changes observed in depression. We found a region-specific influence of the GR-genotype on BDNF levels both under basal and stress conditions. Steady-state levels of BDNF mRNA were unchanged in hippocampus while up-regulated in frontal lobe of GR(+/-) mice. Following exposure to an acute stress, increased processing from pro- to mature BDNF was observed in hippocampal synaptosomes of wild-type mice, but not in GR mutants. Furthermore, the stress-dependent modulation of Arc was impaired in the hippocampus of GR(+/-) mice. These results indicate that GR(+/-) mice show overt differences in the stress-induced modulation of neuroplastic proteins, which may contribute to pathologic conditions that may originate following gene x environment interaction.
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PMID:Depression-prone mice with reduced glucocorticoid receptor expression display an altered stress-dependent regulation of brain-derived neurotrophic factor and activity-regulated cytoskeleton-associated protein. 1907 32

Neurotransmitter- or neurotrophin-regulated intracellular signaling in the hippocampus is hypothesized to contribute to depression and antidepressant (ADT) efficacy. Extracellular signal-regulated kinase 1/2 (ERK1/2) is downstream of several receptor types and regulates transcriptional activity of many targets; ERK1/2 may thereby influence mood and affect. Using a novel, ADT-sensitive depression model in mice, we show that prior corticosterone exposure decreases motivated behavior, sucrose consumption, and pERK1/2 in the dentate gyrus, but not in CA1/CA3. Notably, prefrontal cortical targets were also regulated. Our data suggest ADTs restore hippocampal pERK1/2 after stress-related insult, and potentially reveal a novel role for prefrontal neurotrophins in depressive-like symptomology.
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PMID:Corticosterone regulates pERK1/2 map kinase in a chronic depression model. 1912 Jan 49

Vitamin D, a multipurpose steroid hormone vital to health, has been increasingly implicated in the pathology of cognition and mental illness. Hypovitaminosis D is prevalent among older adults, and several studies suggest an association between hypovitaminosis D and basic and executive cognitive functions, depression, bipolar disorder, and schizophrenia. Vitamin D activates receptors on neurons in regions implicated in the regulation of behavior, stimulates neurotrophin release, and protects the brain by buffering antioxidant and anti-inflammatory defenses against vascular injury and improving metabolic and cardiovascular function. Although additional studies are needed to examine the impact of supplementation on cognition and mood disorders, given the known health benefits of vitamin D, we recommend greater supplementation in older adults.
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PMID:Some new food for thought: the role of vitamin D in the mental health of older adults. 1918 3

Epidemiological studies demonstrate that affective disorders are at least twice as common in women as in men, but surprisingly, very few preclinical studies have been conducted on female experimental animals. Therefore, the necessity of developing valid animal models for studying the pathophysiology of stress-related disorders in women is obvious. Chronic social stress has the potential to induce depression in humans and therefore we characterize here a chronic social instability stress paradigm in female rats. This consists of a 4-week period with alternating stressful social situations, including phases of isolation and crowding, in an unpredictable manner. At the physiological level, increased adrenal weight and plasma corticosterone levels indicated hyperactivity of the hypothalamus-pituitary-adrenal axis. Elevated plasma luteinizing hormone and disruption of the estrus cycle together with increased serum prolactin levels revealed disrupted regulation of the hypothalamus-pituitary-gonadal axis. Body temperature regulation was affected during the last week of stress such that stressed rats reduced their body temperature less during the rest phase than the controls, thus exhibiting a flattened temperature curve. Behaviorally, chronically stressed rats showed reduced sucrose preference and food intake. However, we did not observe any effect of stress on performance in the forced swim test and hippocampal neurotrophin levels were similarly unaffected. Our results indicate that, by using this social instability paradigm, female rats can be kept under chronic stress for weeks without habituation, and that ultimately the animals develop a depressive-like phenotype. This model may provide a valuable tool for further analyses of the neurobiology of stress-related disorders in women and has the potential to serve as a paradigm for screening novel antidepressant drugs with special efficacy in women.
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PMID:Chronic social instability stress in female rats: a potential animal model for female depression. 1935 82

Mood disorders are not merely attributed to the functional defect of neurotransmission, but also are due to the structural impairment of neuroplasticity. Chronic stress decreases neurotrophin levels, precipitating or exacerbating depression; conversely, antidepressants increase expression of various neurotrophins (e.g., brain-derived neurotrophic factor and vascular endothelial growth factor), thereby blocking or reversing structural and functional pathologies via promoting neurogenesis. Since the worldwide approval of lithium therapy in 1970, lithium has been used for its anti-manic, antidepressant, and anti-suicidal effects, yet the therapeutic mechanisms at the cellular level remain not-fully defined. During the last five years, multiple lines of evidence have shown that the mood stabilization and neurogenesis by lithium are due to the lithium-induced inhibition of glycogen synthase kinase-3beta (GSK-3beta), allowing accumulation of beta-catenin and beta-catenin-dependent gene transcriptional events. Altered levels of GSK-3beta and beta-catenin are associated with various neuropsychiatric and neurodegenerative diseases, while various classical neuropsychiatric drugs inhibit GSK-3beta and up-regulate beta-catenin expression. In addition, evidence has emerged that insulin-like growth factor-I enhances antidepression, anti-anxiety, memory, neurogenesis, and angiogenesis; antidepressants up-regulate expression of insulin-like growth factor-I, while insulin-like growth factor-I up-regulates brain-derived neurotrophic factor expression and its receptor TrkB level, as well as brain-derived neurotrophic factor-induced synaptic protein levels. More importantly, physical exercise and healthy diet raise transport of peripheral circulating insulin-like growth factor I into the brain, reinforcing the expression of neurotrophins (e.g., brain-derived neurotrophic factor) and the strength of cell survival signalings (e.g., phosphoinositide 3-kinase / Akt / GSK-3beta pathway). This review will focus on the rapidly advancing new trends in the last five years about lithium, GSK-3beta/beta-catenin, and neurotrophin cascades.
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PMID:Lithium and neuropsychiatric therapeutics: neuroplasticity via glycogen synthase kinase-3beta, beta-catenin, and neurotrophin cascades. 1942 50

Postsynaptic cells generate positive and negative signals that retrogradely modulate presynaptic function. At developing neuromuscular synapses, prolonged stimulation of muscle cells induces sustained synaptic depression. We provide evidence that pro-brain-derived neurotrophic factor (BDNF) is a negative retrograde signal that can be converted into a positive signal by metalloproteases at the synaptic junctions. Application of pro-BDNF induces a dramatic decrease in synaptic efficacy followed by a retraction of presynaptic terminals, and these effects are mediated by presynaptic pan-neurotrophin receptor p75 (p75(NTR)), the pro-BDNF receptor. A brief stimulation of myocytes expressing cleavable or uncleavable pro-BDNF elicits synaptic potentiation or depression, respectively. Extracellular application of metalloprotease inhibitors, which inhibits the cleavage of endogenous pro-BDNF, facilitates the muscle stimulation-induced synaptic depression. Inhibition of presynaptic p75(NTR) or postsynaptic BDNF expression also blocks the activity-dependent synaptic depression and retraction. These results support a model in which postsynaptic secretion of a single molecule, pro-BDNF, may stabilize or eliminate presynaptic terminals depending on its proteolytic conversion at the synapses.
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PMID:Pro-BDNF-induced synaptic depression and retraction at developing neuromuscular synapses. 1945 Dec 78

Although stress represents the major environmental element of susceptibility for mood disorders, the relationship between stress and disease remains to be fully established. In the present article we review the evidence in support for a role of neuronal plasticity, and in particular of neurotrophic factors. Even though decreased levels of norepinephrine and serotonin may underlie depressive symptoms, compelling evidence now suggests that mood disorders are characterized by reduced neuronal plasticity, which can be brought about by exposure to stress at different stages of life. Indeed the expression of neurotrophic molecules, such as the neurotrophin BDNF, is reduced in depressed subjects as well as in experimental animals exposed to adverse experience at early stages of life or at adulthood. These changes show an anatomical specificity and might be sustained by epigenetic mechanisms. Pharmacological intervention may normalize such defects and improve neuronal function through the modulation of the same factors that are defective in depression. Several studies have demonstrated that chronic, but not acute, antidepressant treatment increases the expression of BDNF and may enhance its localization at synaptic level. Antidepressant treatment can normalize deficits in neurotrophin expression produced by chronic stress paradigms, but may also alter the modulation of BDNF under acute stressful conditions. In summary, there is good agreement in considering neuronal plasticity, and the expression of key proteins such as the neurotrophin BDNF, as a central player for the effects of stress on brain function and its implication for psychopathology. Accordingly, effective treatments should not limit their effects to the control of neurotransmitter and hormonal dysfunctions, but should be able to normalize defective mechanisms that sustain the impairment of neuronal plasticity.
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PMID:Neuronal plasticity: a link between stress and mood disorders. 1954 29

The neurotrophin brain-derived neurotrophic factor (BDNF) has been implicated in depression and anxiety. Antidepressants and exercise increase BDNF expression, and both have an antidepressant and anxiolytic activity. To further characterize the association of anxiety, BDNF and exercise, we studied panic disorder patients (n=12) and individually matched healthy control subjects (n=12) in a standardized exercise paradigm. Serum samples for BDNF analyses were taken before and after 30min of exercise (70 VO(2max)) or quiet rest. The two conditions were separated by 1 week and the order was randomized. Non-parametric statistical analyses were performed. There was a negative correlation of BDNF concentrations and subjective arousal at baseline (r=-0.42, p=0.006). Compared to healthy control subjects, patients with panic disorder had significantly reduced BDNF concentrations at baseline and 30min of exercise significantly increased BDNF concentrations only in these patients. Our results suggest that acute exercise ameliorates reduced BDNF concentrations in panic disorder patients and raise the question whether this is also found after long-term exercise training and if it is related to the therapeutic outcome.
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PMID:Acute exercise ameliorates reduced brain-derived neurotrophic factor in patients with panic disorder. 1968 3

Diverse factors such as changes in neurotrophins and brain plasticity have been proposed to be involved in the actions of antidepressant drugs (ADs). However, in mouse models of depression based on chronic stress, it is still unclear whether simultaneous changes in behavior and neurotrophin expression occur and whether these changes can be corrected or prevented comparably by chronic administration of ADs or genetic manipulations that produce antidepressant-like effects such as the knockout of the norepinephrine transporter (NET) gene. Here we show that chronic restraint or social defeat stress induce comparable effects on behavior and changes in the expression of neurotrophins in depression-related brain regions. Chronic stress caused down-regulation of BDNF, nerve growth factor, and neurotrophin-3 in hippocampus and cerebral cortex and up-regulation of these targets in striatal regions. In wild-type mice, these effects could be prevented by concomitant chronic administration of five pharmacologically diverse ADs. In contrast, NET knock out (NETKO) mice were resistant to stress-induced depressive-like changes in behavior and brain neurotrophin expression. Thus, the resistance of the NETKO mice to the stress-induced depression-associated behaviors and biochemical changes highlight the importance of noradrenergic pathways in the maintenance of mood. In addition, these mice represent a useful model to study depression-resistant behaviors, and they might help to provide deeper insights into the identification of downstream targets involved in the mechanisms of antidepressants.
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PMID:Knockout of the norepinephrine transporter and pharmacologically diverse antidepressants prevent behavioral and brain neurotrophin alterations in two chronic stress models of depression. 1969 5

Depression and suicidal behavior have recently been shown to be associated with disturbances in structural and synaptic plasticity. Brain-derived neurotrophic factor (BDNF), one of the major neurotrophic factors, plays an important role in the maintenance and survival of neurons and in synaptic plasticity. Several lines of evidence suggest that BDNF is involved in depression, such that the expression of BDNF is decreased in depressed patients. In addition, antidepressants up-regulate the expression of BDNF. This has led to the proposal of the "neurotrophin hypothesis of depression". Increasing evidence demonstrates that suicidal behavior is also associated with lower expression of BDNF, which may be independent from depression. Recent genetic studies also support a link of BDNF to depression/suicidal behavior. Not only BDNF, but abnormalities in its cognate receptor tropomycin receptor kinase B (TrkB) and its splice variant (TrkB.T1) have also been reported in depressed/suicidal patients. It has been suggested that epigenetic modulation of the Bdnf and Trkb genes may contribute to their altered expression and functioning. More recently, impairment in the functioning of pan75 neurotrophin receptor has been reported in suicide brain specimens. pan75 neurotrophin receptor is a low-affinity neurotrophin receptor that, when expressed in conjunction with low availability of neurotropins/Trks, induces apoptosis. Overall, these studies suggest the possibility that BDNF and its mediated signaling may participate in the pathophysiology of depression and suicidal behavior. This review focuses on the critical evidence demonstrating the involvement of BDNF in depression and suicide.
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PMID:Brain-derived neurotrophic factor: role in depression and suicide. 1972 23


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