Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study examined the effects of footshock stress and re-exposure to cues previously associated with footshock on expression of brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus of male rats. Exposure to twenty 0.5-s 0.4-mA footshocks co-terminating with 70 dB, 5-s long pure tones over 60 min decreased dentate gyrus BDNF mRNA by 21.5%. Baseline BDNF mRNA levels returned to normal by two days after footshock exposure. Re-exposure for 60 min to the chamber and tones previously paired with 0.4 mA footshock decreased BDNF mRNA by 12%. Re-exposure to the conditioning chamber and tones previously paired with 0.6 mA footshock over 60 min decreased BDNF mRNA by 20.8%. The data suggest that psychological, as well as unconditioned physical stress, can decrease hippocampal BDNF mRNA. Possible implications for stress-related and other neuropsychiatric disorders associated with deficits in hippocampal function and volume, such as depression, post-traumatic stress disorder, and Alzheimer's Disease, are discussed.
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PMID:Downregulation of BDNF mRNA in the hippocampal dentate gyrus after re-exposure to cues previously associated with footshock. 1209 87

Clinical neuroscience enters a new era in understanding the pathophysiology of depressive illness and the mode of action of antidepressant therapy. While elucidation of factors that lead to depression is still in its infancy, biochemical malfunctions appear to have well defined morphological correlations, especially in the hippocampus. Hippocampus is one of the main sites in the brain habouring neural stem cells. Cytokines and neurotrophic factors like brain-derived neurotrophic factor (BDNF) play a pivotal role in neural plasticity and potentially influence growth and migration of these progenitors. Not surprisingly, antidepressant drugs interfering with neurotransmitters such as serotonin (5-HT) influence neurotrophins like BDNF, since 5-HT homeostasis is essential for brain development, neurogenesis, and neuroplasticity as well as complex behavior. In this review, the new area of neural stem cell research and the avenues of ongoing and future research sustaining the development of novel treatments for depression will be explored.
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PMID:When cells become depressed: focus on neural stem cells in novel treatment strategies against depression. 1211 81

Previous studies have shown that 5-hydroxytryptamine(2A) (5-HT(2A)) receptor activation induces changes in the pattern of brain-derived neurotrophic factor (BDNF) mRNA expression in the neocortex and hippocampus, and that 5-HT(2A) receptor blockade interferes with the induction of BDNF mRNA by stress. Recent studies have also shown that activation of metabotropic glutamate group II (mGlu2/3) receptors suppresses 5-HT(2A) receptor-stimulated excitatory postsynaptic potentials/currents (EPSP/Cs) in pyramidal neurons in medial prefrontal cortex. Conversely, blockade of mGlu2/3 receptors enhances 5-HT-induced EPSCs. The current study examined the effects of the highly selective mGlu2/3 agonist (1S,2S,5R,6S)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylate monohydrate (LY354740) and the mGlu2/3 antagonist 2S-2-amino-2-(1S,2S-2-carboxycycloprop-1-yl)-3(xanthy-9-yl)propanoic acid (LY341495) on BDNF mRNA expression in medial prefrontal cortex induced by the hallucinogen and 5-HT(2A/2B/2C) agonist 1-(2,5-dimethoxy-4-iodophenethyl)-2-aminopropane (DOI). LY354740 (0.1-10 mg/kg) dose-dependently suppressed DOI-induced BDNF mRNA levels in medial prefrontal cortex. In contrast, the mGlu2/3 antagonist LY341495 (1 mg/kg) enhanced DOI-induced BDNF mRNA levels. BDNF mRNA expression was not altered by administration of the mGlu agonist or the antagonist alone. These results are discussed with respect to a potential role for group II mGlu agonists in the treatment of depression and schizophrenia.
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PMID:Modulation of DOI-induced increases in cortical BDNF expression by group II mGlu receptors. 1211 85

Recent evidence shows that neurotrophins are not only involved in neuronal survival and differentiation during development but also in modulating synaptic strength in the mature brain. To understand how neurotrophins alter this synaptic modification, we have investigated the effect of brain-derived neurotrophic factor (BDNF) on long-term depression (LTD) at Schaffer collateral-CA1 synapses in rat hippocampal slices. The slices treated with BDNF for 5 min showed significantly less LTD in response to a 1-Hz tetanus compared with controls but displayed normal LTD when the afferents were tetanized at 10 Hz. Because BDNF enhanced long-term potentiation (LTP) induced by a 30-Hz tetanus, the synaptic modification threshold (theta(m)) as defined in the 'BCM' theory of Bienenstock Cooper & Monroe [Bienenstock et al. (1982), J. Neurosci., 2, 32-48] was not shifted. BNDF is likely to alter the capability of the plastic changes in synaptic efficacy, i.e. to produce an upward shift in the BCM curve. The suppressive effect of BDNF on LTD was prevented by either the tyrosine kinase (Trk) receptor inhibitor K252a or the phospholipase C inhibitor U73122. Thus, TrkB activation may attenuate LTD through phospholipase C signalling pathway.
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PMID:BDNF attenuates hippocampal LTD via activation of phospholipase C: implications for a vertical shift in the frequency-response curve of synaptic plasticity. 1215 39

A large body of evidence has established a link between stressful life events and development or exacerbation of depression. At the cellular level, evidence has emerged indicating neuronal atrophy and cell loss in response to stress and in depression. At the molecular level, it has been suggested that these cellular deficiencies, mostly detected in the hippocampus, result from a decrease in the expression of brain-derived neurotrophic factor (BDNF) associated with elevation of glucocorticoids. Thus, an increase in expression of BDNF, facilitating both neuronal survival and neurogenesis, is thought to represent a converging mechanism of action of various types of antidepressant treatments (e.g., antidepressant drugs and transcranial magnetic stimulation). However, as also revealed by converging lines of evidence, high levels of glucocorticoids down-regulate hippocampal synaptic connectivity ('negative' metaplasticity), whereas an increase in expression of BDNF up-regulates connectivity in the hippocampus ('positive' metaplasticity). Therefore, antidepressant treatments might not only restore cell density but also regulate higher-order synaptic plasticity in the hippocampus by abolishing 'negative' metaplasticity, and thus restore hippocampal cognitive processes that are altered by stress and in depressed patients. This antidepressant regulatory effect on hippocampal synaptic plasticity function, which may, in turn, suppress 'negative' metaplasticity in other limbic structures, is discussed.
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PMID:Stress, metaplasticity, and antidepressants. 1242 Aug 2

Depression is an incapacitating disease which needs appropriate treatment. This article reviews the pharmacology of antidepressant drugs and the future perspectives of treating mood disorders such as depression. The foremost theory for explaining the biological basis of depression has been the monoamine hypothesis. Depression is due to a deficiency in one or other biogenic monoamines (serotonin, 5-HT; noradrenaline, NA; dopamine, DA). Antidepressant drugs are therefore classified according to their ability to improve monoaminergic transmission. Since this first theory, other explanations based on abnormal function of monoamine receptors or associated with impaired signalling pathways have been suggested. Notable progress has been accomplished in the treatment of major depressive disorders with new compounds recently discovered (selective serotonin reuptake inhibitors: SSRI; serotonin noradrenaline reuptake inhibitors: SNRI). Behavioural, electrophysiological and microdialysis studies have shown that serotonin (5-HT) receptors, mainly 5-HT1A, 5-HT1B and 5-HT2C sub-types, exert a key role in modulating antidepressant activity. Indirect activation of neurotransmitter receptors by antidepressants may also lead, via increases in endogenous levels of serotonin in synapses in specific brain regions, to activation of various G proteins coupled to a receptor, signal of transduction, transcription factors and neurotrophic factors such as brain-derived neurotrophic factor (BDNF). Thus, depression may be considered as a transduction mechanism anomaly. This hypothesis needs to be clarified by molecular biology. Although antidepressants have improved the therapeutic potential compared to tricyclics (TCA) in terms of reduced side effects, a number of problems still occur with these drugs. Clinical effects are not always observed until after this time has elapsed (4-6 weeks) and a substantial proportion of depressed patients show only partial or no response to antidepressants. Knowledge of the existence of links between neurotransmitter systems and the discovery of the most specific target, 5-HT receptors, should lead to improvements in antidepressant therapy. Developing drugs using innovative mechanisms such as directly acting on 5-HT receptors (5-HT1A agonists or 5-HT2 antagonists), would appear to be useful in the treatment of depression. The use of antidepressants in anxiety disorders such as obsessional compulsive disorders and even generalised anxiety, highlights the distinction between antidepressants and classic anxiolytics such as benzodiazepines, or even buspirone.
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PMID:[Mechanism of action of antidepressants and therapeutic perspectives]. 1242 59

Chronic application of brain-derived neurotrophic factor (BDNF) induces new selective synthesis of non-L-type Ca2+ channels (N, P/Q, R) at the soma of cultured hippocampal neurons. As N- and P/Q-channels support neurotransmitter release in the hippocampus, this suggests that BDNF-treatment may enhance synaptic transmission by increasing the expression of presynaptic Ca2+ channels as well. To address this issue we studied the long-term effects of BDNF on miniature and stimulus-evoked GABAergic transmission in rat embryo hippocampal neurons. We found that BDNF increased the frequency of miniature currents (mIPSCs) by approximately 40%, with little effects on their amplitude. BDNF nearly doubled the size of evoked postsynaptic currents (eIPSCs) with a marked increase of paired-pulse depression, which is indicative of a major increase in presynaptic activity. The potentiation of eIPSCs was more relevant during the first two weeks in culture, when GABAergic transmission is depolarizing. BDNF action was mediated by TrkB-receptors and had no effects on: (i) the amplitude and dose-response of GABA-evoked IPSCs and (ii) the number of GABA(A) receptor clusters and the total functioning synapses, suggesting that the neurotrophin unlikely acted postsynaptically. In line with this, BDNF affected the contribution of voltage-gated Ca2+ channels mediating evoked GABAergic transmission. BDNF drastically increased the fraction of evoked IPSCs supported by N- and P/Q-channels while it decreased the contribution associated with R- and L-types. This selective action resembles the previously observed up-regulatory effects of BDNF on somatic Ca2+ currents in developing hippocampus, suggesting that potentiation of presynaptic N- and P/Q-channel signalling belongs to a manifold mechanism by which BDNF increases the efficiency of stimulus-evoked GABAergic transmission.
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PMID:BDNF up-regulates evoked GABAergic transmission in developing hippocampus by potentiating presynaptic N- and P/Q-type Ca2+ channels signalling. 1249 24

Nerve growth factor was the first identified protein with anti-apoptotic activity on neurons. This prototypic neurotrophic factor, together with the three structurally and functionally related growth factors brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and neurotrophin-4/5 (NT4/5), forms the neurotrophin protein family. Target T cells for neurotrophins include many neurons affected by neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and peripheral polyneuropathies. In addition, the neurotrophins act on neurons affected by other neurological and psychiatric pathologies including ischemia, epilepsy, depression and eating disorders. Work with cell cultures and animal models provided solid support for the hypothesis that neurotrophins prevent neuronal death. While no evidence exists that a lack of neurotrophins underlies the etiology of any neurodegenerative disease, these studies have spurred on hopes that neurotrophins might be useful symptomatic-therapeutic agents. However first clinical trials led to variable results and severe side effects were observed. For future therapeutic use of the neurotrophins it is therefore crucial to expand our knowledge about their physiological functions as well as their pharmacokinetic properties. A major challenge is to develop methods for their application in effective doses and in a precisely timed and localized fashion.
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PMID:Neurotrophins. 1257 26

Nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) are proteins involved in neuronal survival and plasticity of dopaminergic, cholinergic and serotonergic neurons in the central nervous system (CNS). Moreover, it has been hypothesized that these molecules play a role in the pathophysiology as well as treatment of depression. Using an animal model of depression, the Flinders Sensitive Line (FSL) rats and their controls, the Flinders Resistant Line (FRL), we investigated the effects of electroconvulsive stimuli (ECS) on brain NGF and BDNF. ECS or SHAM ECS were administered eight times, with a 48-h interval between each treatment. NGF and BDNF were measured with enzyme-linked immunosorbent assay (ELISA). In the hippocampus ECS increased NGF concentration in FSL but not FRL rats. ECS decreased NGF concentration in the frontal cortex of FSL rats. In both FSL and FRL rats ECS increased NGF levels in the striatum. In contrast, ECS did not change BDNF concentration in hippocampus, frontal cortex and striatum of FSL and FRL rats. Our data support the notion that neurotrophin concentrations may be altered by ECS.
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PMID:Electroconvulsive stimuli alter nerve growth factor but not brain-derived neurotrophic factor concentrations in brains of a rat model of depression. 1263 36

Depression is a highly prevalent condition in adult population. Research on the mechanism of action of antidepressant drugs is also expected to allow a better comprehension about its etiopathogenesis. First theories about neurobiology of depression pointed out the monoaminergic modifications elicited by antidepressants. However, these changes could not be correlated with the latency of action observed in their clinical use. In 1997, with the formulation of genomic theory of depression, old theories and new knowledge about cellular and molecular effects of antidepressant treatment became congruent. The main goal of this paper is to review this theory and the scientific papers in which it is supported. Scientific evidences against genomic theory of antidepressant action are also mentioned. CREB's participation in antidepressant response, as well as BDNF trophic effect and their intracellular signaling pathways are described, as many of these molecules could become targets for the action of new antidepressants.
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PMID:[New perspectives of the mechanism of action of antidepressants arised from genomic theory of depression]. 1269 Apr 7


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