Immobilization stress induces cell death through production of reactive oxygen species in the mouse cerebral cortex

Stress exposure alters brain mRNA expression of the genes involved in insulin signalling, an effect modified by a high fat/high fructose diet and cinnamon supplement

In occidental societies, high fat and high sugar diets often coincide with episodes of stress. The association is likely to modify brain energy control. Brain insulin signalling is rarely studied in stressed individuals consuming high fat diets. Furthermore the effects of cinnamon supplement are not known in these conditions. Therefore, we exposed rats, over a 12-week period, to a control (C) or a high fat/high fructose (HF/HFr) diet that induces peripheral insulin resistance. A cinnamon supplement (C+CN and HF/HFr +CN) was added or not. After diet exposure, one group of rats was exposed to a 30-min restraint followed by a 10-min open-field test, their combination featuring a moderate stressor, the other rats staying unstressed in their home cages. The insulin signalling in hippocampus and frontal cortex was studied through the mRNA expression of the following genes: insulin receptor (Ir), insulin receptor substrate (Irs1), glucose transporters (Glut1 and Glut3), glycogen synthase (Gys1) and their modulators, Akt1 and Pten. In C rats, stress enhanced the expression of Ir, Irs1, Glut1, Gys1 and Akt1 mRNA. In C+CN rats, stress induced an increase in Pten but a decrease in Gys1 mRNA expression. In HF/HFr rats, stress was associated with an increase in Pten mRNA expression. In HF/HFr+CN rats, stress increased Pten mRNA expression but also decreased Gys1 mRNA expression. This suggests that a single moderate stress favours energy refilling mechanisms, an effect blunted by a previous HF/HFr diet and cinnamon supplement.

Positive Modulation of Pink Nelumbo nucifera Flowers on Memory Impairment, Brain Damage, and Biochemical Profiles in Restraint Rats

Due to the crucial role of oxidative stress in the stress-induced memory deficit, the benefit of substance possessing antioxidant effect is focused. Since no data are available, we aimed to determine the effect of Nelumbo nucifera flowers extract on spatial memory and hippocampal damage in stressed rats. Male Wistar rats, weighing 250-350 g, were orally given N. nucifera extract at doses of 10, 10, and 200 mg·kg(-1) 45 minutes before the exposure to 12-hour restraint stress. The spatial memory and serum corticosterone were assessed at 7 and 14 days of study period. At the end of study, acetylcholinesterase (AChE), monoamine oxidase type A and monoamine oxidase type B (MAO-A and MAO-B), oxidative stress status, neuron density, and Ki67 expression in hippocampus were also assessed. The results showed that N. nucifera extract decreased memory deficit and brain damage, serum corticosterone, oxidative stress status, AChE, and MAO-A and MAO-B activities but increased neuron density and Ki67 expression in hippocampus. These suggested that the improved oxidative stress status, adult neurogenesis, and cholinergic and monoaminergic functions might be responsible for the protective effect against stress-related brain damage and dysfunction of the extract. Therefore, N. nucifera extract is the potential neuroprotective and memory enhancing agent. However, further researches are still required.

Oxidative & nitrosative stress in depression: why so much stress?

Many studies support a crucial role for oxidative & nitrosative stress (O&NS) in the pathophysiology of unipolar and bipolar depression. These disorders are characterized inter alia by lowered antioxidant defenses, including: lower levels of zinc, coenzyme Q10, vitamin E and glutathione; increased lipid peroxidation; damage to proteins, DNA and mitochondria; secondary autoimmune responses directed against redox modified nitrosylated proteins and oxidative specific epitopes. This review examines and details a model through which a complex series of environmental factors and biological pathways contribute to increased redox signaling and consequently increased O&NS in mood disorders. This multi-step process highlights the potential for future interventions that encompass a diverse range of environmental and molecular targets in the treatment of depression.

Role of immune-inflammatory and oxidative and nitrosative stress pathways in the etiology of depression: therapeutic implications

Accumulating data have led to a re-conceptualization of depression that emphasizes the role of immune-inflammatory processes, coupled to oxidative and nitrosative stress (O&NS). These in turn drive the production of neuroregulatory tryptophan catabolites (TRYCATs), driving tryptophan away from serotonin, melatonin, and N-acetylserotonin production, and contributing to central dysregulation. This revised perspective better encompasses the diverse range of biological changes occurring in depression and in doing so provides novel and readily attainable treatment targets, as well as potential screening investigations prior to treatment initiation. We briefly review the role that immune-inflammatory, O&NS, and TRYCAT pathways play in the etiology, course, and treatment of depression. We then discuss the pharmacological treatment implications arising from this, including the potentiation of currently available antidepressants by the adjunctive use of immune- and O&NS-targeted therapies. The use of such a frame of reference and the treatment benefits attained are likely to have wider implications and utility for depression-associated conditions, including the neuroinflammatory and (neuro)degenerative disorders.

Effect of glucocorticoid-induced oxidative stress on the expression of Cbfa1

Glucocorticoids therapy is strongly limited since extended glucocorticoids can cause serious side effects, including increased susceptibility to develop the bone disease osteoporosis. Despite its side effects recognized importance to clinicians, seldom is known about how glucocorticoids directly impact bone-forming osteoblasts. Previous studies showed that dexamethasone (DEX) induces excessive production of reactive oxygen species (ROS), and causes oxidative stress in rat hippocampal slice cultures. To assess the implications and investigate the mechanisms of glucocorticoid-elicited osteoporosis, we hypothesize that DEX exposure induces oxidative stress which leads to decreased Cbfa1 mRNA expression, and predict that the antioxidant N-acetylcysteine (NAC) mitigates the damaging effects of DEX. Oxidative stress is implicated in osteoporosis. Furthermore, the osteoblast transcriptional factor Cbfa1 is reported to play a protective role against osteoporosis in postmenopausal women. Cells treated with (0.1, 1, 10μM) DEX exhibited signs of oxidative damages including depletion in total antioxidant capacity (T-AOC), increased ROS formation, and enhanced lipid peroxidation. Cbfa1 mRNA expression, by RT-PCR, was significantly reduced after exposure to (0.1, 1, 10μM) DEX. Pretreatment with the antioxidant NAC (2mM) prevented DEX-induced decrease in Cbfa1 mRNA. This study provides insight into the underlying mechanisms of high dose DEX-induced osteotoxicity. DEX (0.1, 1, 10μM) decreases the expression of Cbfa1 mRNA and inhibits differentiation and function of osteoblasts by inducing oxidative stress. The antioxidant NAC can mitigate the oxidative stress damaging effects of DEX. In addition, this study distinguishes itself by identifying Cbfa1 as a target for high dose DEX-induced osteotoxicity.

Oxidative/nitrosative stress and antidepressants: targets for novel antidepressants

The brain is an organ predisposed to oxidative/nitrosative stress. This is especially true in the case of aging as well as several neurodegenerative diseases. Under such circumstances, a decline in the normal antioxidant defense mechanisms leads to an increase in the vulnerability of the brain to the deleterious effects of oxidative damage. Highly reactive oxygen/nitrogen species damage lipids, proteins, and mitochondrial and neuronal genes. Unless antioxidant defenses react appropriately to damage inflicted by radicals, neurons may experience microalteration, microdysfunction, and degeneration. We reviewed how oxidative and nitrosative stresses contribute to the pathogenesis of depressive disorders and reviewed the clinical implications of various antioxidants as future targets for antidepressant treatment.

The neuroprogressive nature of major depressive disorder: pathways to disease evolution and resistance, and therapeutic implications

In some patients with major depressive disorder (MDD), individual illness characteristics appear consistent with those of a neuroprogressive illness. Features of neuroprogression include poorer symptomatic, treatment and functional outcomes in patients with earlier disease onset and increased number and length of depressive episodes. In such patients, longer and more frequent depressive episodes appear to increase vulnerability for further episodes, precipitating an accelerating and progressive illness course leading to functional decline. Evidence from clinical, biochemical and neuroimaging studies appear to support this model and are informing novel therapeutic approaches. This paper reviews current knowledge of the neuroprogressive processes that may occur in MDD, including structural brain consequences and potential molecular mechanisms including the role of neurotransmitter systems, inflammatory, oxidative and nitrosative stress pathways, neurotrophins and regulation of neurogenesis, cortisol and the hypothalamic-pituitary-adrenal axis modulation, mitochondrial dysfunction and epigenetic and dietary influences. Evidence-based novel treatments informed by this knowledge are discussed.

Burst of succinate dehydrogenase and α-ketoglutarate dehydrogenase activity in concert with the expression of genes coding for respiratory chain proteins underlies short-term beneficial physiological stress in mitochondria

Conditions for the realization in rats of moderate physiological stress (PHS) (30-120 min) were selected, which preferentially increase adaptive restorative processes without adverse responses typical of harmful stress (HST). The succinate dehydrogenase (SDH) and α-ketoglutarate dehydrogenase (KDH) activity and the formation of reactive oxygen species (ROS) in mitochondria were measured in lymphocytes by the cytobiochemical method, which detects the regulation of mitochondria in the organism with high sensitivity. These mitochondrial markers undergo an initial 10-20-fold burst of activity followed by a decrease to a level exceeding the quiescent state 2-3-fold by 120 min of PHS. By 30-60 min, the rise in SDH activity was greater than in KDH activity, while the activity of KDH prevailed over that of SDH by 120 min. The attenuation of SDH hyperactivity during PHS occurs by a mechanism other than oxaloacetate inhibition developed under HST. The dynamics of SDH and KDH activity corresponds to the known physiological replacement of adrenergic regulation by cholinergic during PHS, which is confirmed here by mitochondrial markers because their activity reflects these two types of nerve regulation, respectively. The domination of cholinergic regulation provides the overrestoration of expenditures for activity. In essence, this phenomenon corresponds to the training of the organism. It was first revealed in mitochondria after a single short-time stress episode. The burst of ROS formation was congruous with changes in SDH and KDH activity, as well as in ucp2 and cox3 expression, while the activity of SDH was inversely dependent on the expression of the gene of its catalytic subunit in the spleen. As the SDH activity enhanced, the expression of the succinate receptor decreased with subsequent dramatic rise when the activity was becoming lower. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaption and therapy.

Mechanistic explanations how cell-mediated immune activation, inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression

This paper reviews that cell-mediated-immune (CMI) activation and inflammation contribute to depressive symptoms, including anhedonia; anxiety-like behaviors; fatigue and somatic symptoms, e.g. illness behavior or malaise; and mild cognitive impairment (MCI). These effects are in part mediated by increased levels of pro-inflammatory cytokines (PICs), e.g. interleukin-1 (IL-1), IL-6 and tumor necrosis factor (TNF)α, and Th-1-derived cytokines, such as IL-2 and interferon (IFN)γ. Moreover, new pathways, i.e. concomitants and sequels of CMI activation and inflammation, were detected in depression: (1) Induction of indoleamine 2,3-dioxygenase (IDO) by IFNγ and some PICs is associated with depleted plasma tryptophan, which may interfere with brain 5-HT synthesis, and increased production of anxiogenic and depressogenic tryptophan catabolites. (2) Increased bacterial translocation may cause depression-like behaviors by activating the cytokine network, oxidative and nitrosative stress (O&NS) pathways and IDO. (3) Induction of O&NS causes damage to membrane ω3 PUFAs, functional proteins, DNA and mitochondria, and autoimmune responses directed against intracellular molecules that may cause dysfunctions in intracellular signaling. (4) Decreased levels of ω3 PUFAs and antioxidants, such as coenzyme Q10, glutathione peroxidase or zinc, are associated with an increased inflammatory potential; more oxidative damage; the onset of specific symptoms; and changes in the expression or functions of brain 5-HT and N-methyl-d-aspartate receptors. (5) All abovementioned factors cause neuroprogression, that is a combination of neurodegeneration, neuronal apoptosis, and lowered neurogenesis and neuroplasticity. It is concluded that depression may be the consequence of a complex interplay between CMI activation and inflammation and their sequels/concomitants which all together cause neuroprogression that further shapes the depression phenotype. Future research should employ high throughput technologies to collect genetic and gene expression and protein data from patients with depression and analyze these data by means of systems biology methods to define the dynamic interactions between the different cell signaling networks and O&NS pathways that cause depression.

Effect of Celastrus paniculatus seed oil (Jyothismati oil) on acute and chronic immobilization stress induced in swiss albino mice

Stress alters the homeostasis and is produced by several factors. Immobilization stress induced due to reduced floor area provided for the mobility results in the imbalance of oxidant and antioxidant status. The modern computer savvy world decreases human mobility in the working environment, leading to the formation of oxygen free radicals and if left untreated might result in severe health problems like hypertension, cardiovascular disease, premature aging and brain dysfunction. Hence, modern medicines rely upon the medicinal plants for some drugs with zero side effects. In this context, Jyothismati oil (JO), extracted from Celastrus paniculatus seeds, was used to treat acute and chronic immobilization induced experimentally. C. paniculatus plant is considered to be rich in antioxidant content and so the seed oil extract's efficacy was tested against immobilization stress in albino mice. The animals were kept in a restrainer for short and long durations, grouped separately and fed with the drug. Animals were sacrificed and the samples were analyzed. The antioxidant enzyme levels of the animals regained and markedly increased in the acute and chronic immobilized groups, respectively. The results suggested that the extract of C. paniculatus seed was highly efficacious in reducing the stress induced by least mobility for hours.

A review on the oxidative and nitrosative stress (O&NS) pathways in major depression and their possible contribution to the (neuro)degenerative processes in that illness

This paper reviews the body of evidence that major depression is accompanied by a decreased antioxidant status and by induction of oxidative and nitrosative (IO&NS) pathways. Major depression is characterized by significantly lower plasma concentrations of a number of key antioxidants, such as vitamin E, zinc and coenzyme Q10, and a lowered total antioxidant status. Lowered antioxidant enzyme activity, e.g. glutathione peroxidase (GPX), is another hallmark of depression. The abovementioned lowered antioxidant capacity may impair protection against reactive oxygen species (ROS), causing damage to fatty acids, proteins and DNA by oxidative and nitrosative stress (O&NS). Increased ROS in depression is demonstrated by increased levels of plasma peroxides and xanthine oxidase. Damage caused by O&NS is shown by increased levels of malondialdehyde (MDA), a by-product of polyunsaturated fatty acid peroxidation and arachidonic acid; and increased 8-hydroxy-2-deoxyguanosine, indicating oxidative DNA damage. There is also evidence in major depression, that O&NS may have changed inactive autoepitopes to neoantigens, which have acquired immunogenicity and serve as triggers to bypass immunological tolerance, causing (auto)immune responses. Thus, depression is accompanied by increased levels of plasma IgG antibodies against oxidized LDL; and increased IgM-mediated immune responses against membrane fatty acids, like phosphatidyl inositol (Pi); oleic, palmitic, and myristic acid; and NO modified amino-acids, e.g. NO-tyrosine, NO-tryptophan and NO-arginine; and NO-albumin. There is a significant association between depression and polymorphisms in O&NS genes, like manganese superoxide dismutase, catalase, and myeloperoxidase. Animal models of depression very consistently show lowered antioxidant defences and activated O&NS pathways in the peripheral blood and the brain. In animal models of depression, antidepressants consistently increase lowered antioxidant levels and normalize the damage caused by O&NS processes. Antioxidants, such as N-acetyl-cysteine, compounds that mimic GPX activity, and zinc exhibit antidepressive effects. This paper reviews the pathways by which lowered antioxidants and O&NS may contribute to depression, and the (neuro)degenerative processes that accompany that illness. It is concluded that aberrations in O&NS pathways are--together with the inflammatory processes--key components of depression. All in all, the results suggest that depression belongs to the spectrum of (neuro)degenerative disorders.

In animal models, psychosocial stress-induced (neuro)inflammation, apoptosis and reduced neurogenesis are associated to the onset of depression

Recently, the inflammatory and neurodegenerative (I&ND) hypothesis of depression was formulated (Maes et al., 2009), i.e. the neurodegeneration and reduced neurogenesis that characterize depression are caused by inflammation, cell-mediated immune activation and their long-term sequels. The aim of this paper is to review the body of evidence that external stressors may induce (neuro)inflammation, neurodegeneration and reduced neurogenesis; and that antidepressive treatments may impact on these pathways. The chronic mild stress (CMS) and learned helplessness (LH) models show that depression-like behaviors are accompanied by peripheral and central inflammation, neuronal cell damage, decreased neurogenesis and apoptosis in the hippocampus. External stress-induced depression-like behaviors are associated with a) increased interleukin-(IL)1β, tumor necrosis factor-α, IL-6, nuclear factor κB, cyclooxygenase-2, expression of Toll-like receptors and lipid peroxidation; b) antineurogenic effects and reduced brain-derived neurotrophic factor (BDNF) levels; and c) apoptosis with reduced levels of Bcl-2 and BAG1 (Bcl-2 associated athanogene 1), and increased levels of caspase-3. Stress-induced inflammation, e.g. increased IL-1β, but not reduced neurogenesis, is sufficient to cause depression. Antidepressants a) reduce peripheral and central inflammatory pathways by decreasing IL-1β, TNFα and IL-6 levels; b) stimulate neuronal differentiation, synaptic plasticity, axonal growth and regeneration through stimulatory effects on the expression of different neurotrophic factors, e.g. trkB, the receptor for brain-derived neurotrophic factor; and c) attenuate apoptotic pathways by activating Bcl-2 and Bcl-xl proteins, and suppressing caspase-3. It is concluded that external stressors may provoke depression-like behaviors through activation of inflammatory, oxidative, apoptotic and antineurogenic mechanisms. The clinical efficacity of antidepressants may be ascribed to their ability to reverse these different pathways.

The new '5-HT' hypothesis of depression: cell-mediated immune activation induces indoleamine 2,3-dioxygenase, which leads to lower plasma tryptophan and an increased synthesis of detrimental tryptophan catabolites (TRYCATs), both of which contribute to the onset of depression

This paper reviews the body of evidence that not only tryptophan and consequent 5-HT depletion, but also induction of indoleamine 2,3-dioxygenase (IDO) and the detrimental effects of tryptophan catabolites (TRYCATs) play a role in the pathophysiology of depression. IDO is induced by interferon (IFN)γ, interleukin-6 and tumor necrosis factor-α, lipopolysaccharides and oxidative stress, factors that play a role in the pathophysiology of depression. TRYCATs, like kynurenine and quinolinic acid, are depressogenic and anxiogenic; activate oxidative pathways; cause mitochondrial dysfunctions; and have neuroexcitatory and neurotoxic effects that may lead to neurodegeneration. The TRYCAT pathway is also activated following induction of tryptophan 2,3-dioxygenase (TDO) by glucocorticoids, which are elevated in depression. There is evidence that activation of IDO reduces plasma tryptophan and increases TRYCAT synthesis in depressive states and that TDO activation may play a role as well. The development of depressive symptoms during IFNα-based immunotherapy is strongly associated with IDO activation, increased production of detrimental TRYCATs and lowered levels of tryptophan. Women show greater IDO activation and TRYCAT production following immune challenge than men. In the early puerperium, IDO activation and TRYCAT production are associated with the development of affective symptoms. Clinical depression is accompanied by lowered levels of neuroprotective TRYCATs or increased levels or neurotoxic TRYCATs, and lowered plasma tryptophan, which is associated with indices of immune activation and glucocorticoid hypersecretion. Lowered tryptophan and increased TRYCATs induce T cell unresponsiveness and therefore may exert a negative feedback on the primary inflammatory response in depression. It is concluded that activation of the TRYCAT pathway by IDO and TDO may be associated with the development of depressive symptoms through tryptophan depletion and the detrimental effects of TRYCATs. Therefore, the TRYCAT pathway should be a new drug target in depression. Direct inhibitors of IDO are less likely to be useful drugs than agents, such as kynurenine hydroxylase inhibitors; drugs which block the primary immune response; compounds that increase the protective effects of kynurenic acid; and specific antioxidants that target IDO activation, the immune and oxidative pathways, and 5-HT as well.

Regulatory role of cannabinoid receptor 1 in stress-induced excitotoxicity and neuroinflammation

Exposure to stress elicits excitoxicity and neuroinflammation in the brain, contributing to cell death and damage in stress-related neurological and neuropsychiatric diseases. The endocannabinoid system is present in stress-responsive neural circuits and has been proposed as an endogenous neuroprotective system activated in some neuropathological scenarios to restore homeostasis. To elucidate the possible regulatory role of cannabinoid receptor 1 (CB1) in stress-induced excitotoxicity and neuroinflammation, both genetic and pharmacological approaches were used alternatively: (1) wild-type (WT) and CB1 knockout mice (CB1-KO) were exposed to immobilization/acoustic stress (2 h/day for 4 days) and (2) to specifically activate CB1, the selective CB1 agonist Arachidonyl-2'-chloroethylamide (ACEA) (2.5 mg/kg) was intraperitoneally administered daily to some groups of animals. Stress exposure increased CB1 mRNA and protein expression in the prefrontal cortex of WT mice in a mechanism related to N-methyl-D-aspartate glutamate receptor activation. Daily ACEA pretreatment prevented stress-induced: (1) upregulation of CB1 mRNA and protein, (2) decrease in glutamate uptake and glutamate astroglial transporter excitatory amino acid transporter 2 expression, (3) increase in consecutive proinflammatory molecules, such as cytokines (tumor necrosis factor-α and MCP-1), nuclear factor kappa B, and enzymatic sources, such as inducible nitric oxide synthase (NOS-2) and cyclooxygenase-2 (COX-2), (4) increase in lipid peroxidation; although having no effect on plasma corticosterone. Interestingly, a possible related mechanism could be the positive ACEA modulation of the antiinflammatory pathway deoxyprostaglandin/peroxisome proliferator-activated receptor γ (15d-PGJ(2)/PPARγ). Conversely, KO animal experiments indicated that a lack of CB1 produces hypothalamic/pituitary/adrenal (HPA) axis dysregulation and exacerbates stress-induced excitotoxic/neuroinflammatory responses. These multifaceted neuroprotective effects suggest that CB1 activation could be a new therapeutic strategy against neurological/neuropsychiatric pathologies with HPA axis dysregulation and an excitotoxic/neuroinflammatory component in their pathophysiology.

Depression: a repair response to stress-induced neuronal microdamage that can grade into a chronic neuroinflammatory condition?

Depression is a major contributor to the global burden of disease and disability, yet it is poorly understood. Here we review data supporting a novel theoretical model for the biology of depression. In this model, a stressful life event leads to microdamage in the brain. This damage triggers an injury repair response consisting of a neuroinflammatory phase to clear cellular debris and a spontaneous tissue regeneration phase involving neurotrophins and neurogenesis. During healing, released inflammatory mediators trigger sickness behavior and psychological pain via mechanisms similar to those that produce physical pain during wound healing. The depression remits if the neuronal injury repair process resolves successfully. Importantly, however, the acute psychological pain and neuroinflammation often transition to chronicity and develop into pathological depressive states. This hypothesis for depression explains substantially more data than alternative models, including why emerging data show that analgesic, anti-inflammatory, pro-neurogenic and pro-neurotrophic treatments have antidepressant effects. Thus, an acute depressive episode can be conceptualized as a normally self-limiting but highly error-prone process of recuperation from stress-triggered neuronal microdamage.

Cyclooxygenase and nitric oxide synthase in the presympathetic neurons in the paraventricular hypothalamic nucleus are involved in restraint stress-induced sympathetic activation in rats

Stress is one of the important factors to activate the sympathetic nervous system. We recently reported that central administration of corticotropin-releasing factor (CRF), known as a stress-related neuropeptide, increases the expression of both cyclooxygenase (COX) and nitric oxide synthase (NOS) in presympathetic neurons in the paraventricular hypothalamic nucleus (PVN). In the present study, therefore, we investigated whether brain COX and NOS can also mediate restraint stress (RS)-induced sympathetic activation by assessing the plasma catecholamine levels and neuronal activation of presympathetic neurons in the PVN. In addition, we examined effects of RS on the expression of both COX and NOS isozymes in the presympathetic PVN neurons. Intraperitoneal administration of an inhibitor for COX-1, COX-2 or inducible NOS (iNOS), but not for neuronal NOS (nNOS), reduced RS-induced elevation of plasma catecholamine levels and Fos expression in the presympathetic PVN neurons. Moreover, RS increased the expression of COX-1, COX-2 and iNOS in the presympathetic PVN neurons, whereas nNOS expression did not change. These results suggest that COX-1, COX-2 and iNOS in the presympathetic PVN neurons mediate acute RS-induced sympathetic activation.

Mechanism of glucocorticoid-induced oxidative stress in rat hippocampal slice cultures

Prolonged stress results in elevation of glucocorticoid (GC) hormones, which can have deleterious effects in the brain. The hippocampus, which has a high concentration of glucocorticoid receptors, is especially vulnerable to increasing levels of GCs. GCs have been suggested to endanger hippocampal neurons by exacerbating the excitotoxic glutamate-calcium-reactive oxygen species (ROS) cascade. In an effort to reveal the mechanisms underlying GC-mediated hippocampal neurotoxicity, we aimed to clarify the molecular pathway of GC-induced ROS increase by using organotypic hippocampal slice cultures. Assays for ROS, using 2',7'-dichlorodihydrofluorescein diacetate fluorescence, showed that treatment of synthetic GC, dexamethasone (DEX) significantly enhanced ROS levels. Time course and dose response analyses indicated that peak amount of ROS was generated at 4 h after treatment with 50 micromol/L DEX. By contrast, other steroid hormones, progesterone and estradiol did not influence ROS production. N-acetyl-L-cysteine completely suppressed ROS produced by DEX. Propidium iodide staining exhibited prominent cell death in the hippocampal layer after 96 h of DEX treatment. RU486, a GC receptor antagonist, almost completely blocked the effect of DEX on ROS production and cell death, indicating that DEX-induced ROS overproduction and hippocampal death are mediated via GC receptors. Real-time reverse transcriptase PCR analysis demonstrated that after DEX treatment the level of glutathione peroxidase mRNA was decreased whereas that of NADPH oxidase mRNA was significantly enhanced. These findings suggest that excess GCs cause hippocampal damage by regulating genes involved in ROS generation.

Some molecular effectors of antidepressant action of quetiapine revealed by DNA microarray in the frontal cortex of anhedonic rats

OBJECTIVES AND METHODS

We have previously demonstrated that quetiapine (QTP) had antidepressant-like action by using the chronic mild stress (CMS) paradigm, an animal model of human depression. The aim of this study was to investigate the molecular mechanism(s) of QTP antidepressant effect by coupling the CMS protocol with Affymetrix microarray technology to screen the entire rat genome for gene changes in the frontal cortex.

RESULTS

The genes regulated by the administration of CMS whose transcription was reversed by chronic QTP treatment (2 mg/kg/day) were 42 (23 upregulated and 19 downregulated). The transcripts that showed no significant altered expression levels in anhedonic rats but were regulated by the administration of QTP were 19 (nine upregulated and 10 downregulated). On the whole, the action of QTP prevented the stress-induced impairment of some processes involved in central nervous system development or having a crucial role for viability of neural cells and cell-cell communications, like regulation of signal transduction, inorganic cation transport, membrane organization, and neurite morphogenesis. For 11 genes (Ptgs2, Gad1, Plcb1, Camk2a, Homer1, Senp2, Junb, Nfib, Hes5, Capon, and Marcks), significant differential expressions were confirmed by real-time reverse-transcriptase polymerase chain reaction.

CONCLUSION

We have shown that chronic QTP treatment prevented anhedonia and reversed, at least in part, the changes of gene expression induced by CMS in the rat frontal cortex. We have also identified and confirmed by two different methods that 11 genes, representing molecular targets of QTP, are presumably the effectors of its clinical efficacy.

The effect of glucocorticoids on bradykinesia induced by immobilization stress

It is well known that the release of glucocorticoids from the adrenal gland is increased in response to many types of stressors and plays a principal role in stress responses. We have shown that the synthesis of prostaglandins (PGs) in the brain is increased under several stress conditions including immobilization (IMO), and that endogenous glucocorticoids counteract this stress-induced PG synthesis. It was also recently reported that IMO damages dopaminergic (DA) neurons in the substantia nigra (SN), which is known to cause symptoms similar to Parkinson's disease (PD). The present study was therefore undertaken to determine the role of glucocorticoids in modulating the signs of PD induced by IMO. The pole test, in which each mouse was placed head upward at the top of a pole and the time taken to turn downward and to arrive on the floor was recorded, and immunohistochemistry for tyrosine hydroxylase (TH) in the SN were performed to evaluate bradykinesia and injury of DA neurons, respectively. Intact and adrenalectomized (ADX) mice were immobilized for 2 h twice, 1 day apart. Both bradykinesia and a decrease in the number of TH-immunoreactive cells in the SN were observed in ADX mice, but not in intact mice, following IMO. These effects of IMO on ADX mice were restored by treatment with corticosterone or indomethacin, a PG synthesis inhibitor. These results suggest that glucocorticoids play a role in preventing the detrimental effect of IMO on nigral DA neurons and resulting bradykinesia, and that this effect of IMO involves PG-mediated mechanisms.

Cytokine levels in sputum of patients with tracheostomy and profound multiple disabilities

BACKGROUND

Airway immunopathogenesis is unclear in patients with profound multiple disabilities (PMD) who undergo tracheostomy.

METHODS

The levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, IL-8, IL-10, and IL-12p70 cytokines were determined in sputum of 28 patients with PMD who underwent tracheostomy and in 14 healthy subjects, using a cytometric bead array.

RESULTS

The concentrations of IL-1beta, IL-6 and IL-8 in the patients were significantly higher than those in controls (p < 0.001). IL-6, and IL-8 levels in eight PMD patients in the febrile period were significantly higher than those in the afebrile period (p < 0.01 and p < 0.05, respectively). Serum CRP levels were slightly elevated in 12 of the 28 patients (43%) in the afebrile period, but there were no significant differences in the level of any cytokine between patients with normal and elevated serum CRP.

CONCLUSION

PMD patients with tracheostomy have chronic airway inflammation.

Involvement of IL-1beta in acute stress-induced worsening of cerebral ischaemia in rats

Stress is known to be one of the risk factors of stroke. Most of the knowledge on the effects of stress on cerebrovascular disease in humans is restricted to catecholamines and glucocorticoids effects on blood pressure and/or development of atherosclerosis. However, few experimental studies have examined the possible mechanisms by which stress may affect stroke outcome. We have used an acute stress protocol consisting of the exposure of male Fischer rats to an acute, single exposure immobilisation protocol (6 h) prior to permanent middle cerebral artery occlusion (MCAO), and we have found that stress worsens behavioural and neurological outcomes and increased infarct size after MCAO. The possible regulatory role of the TNFalpha and IL-1beta was studied by looking at the release of these cytokines in brain. The results of the present study showed an increase in IL-1beta release in cerebral cortex after exposure to acute stress. Brain levels of IL-1beta are also higher in previously stressed MCAO rats than in MCAO animals without stress. Pharmacological blockade of IL-1beta with an antibody anti-IL-1beta led to a decrease in the infarct size as well as in neurological and behavioural deficits after MCAO. In summary, our results indicate that IL-1beta, but not TNFalpha, accounts at least partly for the worsening of MCAO consequences in brain of rats exposed to acute stress.

Antioxidant potential of fluoxetine in comparison to Curcuma longa in restraint-stressed rats

Stress plays a potential role in the onset and exacerbation of depression. Chronic restraint stress in rats, and psychosocial stress in humans, is implicated in the pathophysiology of mood and anxiety disorders. Oxidative damage is an established outcome of restraint stress, which has been suggested to induce many damaging processes contributing to the pathology of stress-induced depression. However, the modulatory role of clinically effective antidepressants, such as fluoxetine, in attenuating oxidative stress has not been well characterized. Therefore, the current study was designed to investigate the antioxidant effects of chronic treatment with fluoxetine in animals submitted to restraint stress. The antioxidant potential of the antidepressant fluoxetine was compared with that of turmeric, used as a standard since it integrates both antioxidant and antidepressant properties. Chronic fluoxetine administration to stressed animals for 21 days prevented restraint stress-induced oxidative damage with an efficacy similar to that of turmeric, as evidenced by significant enhancement of key endogenous antioxidant defense components, comprising the free-radical scavenging enzymes, superoxide:superoxide oxidoreductase (EC 1.15.1.1), hydrogen-peroxide:hydrogen-peroxide oxidoreductase (EC 1.11.1.6), glutathione S-transferase (EC 2.5.1.18) and glutathione:NADP(+)oxidoreductase (EC 1.8.1.7), as well as non-enzymatic antioxidants, GSH, glucose and uric acid, which were severely depleted by restraint stress in animals receiving no treatment. Oxidative stress markers, (S)-lactate:NAD(+) oxidoreductase activity (EC 1.1.1.27), malondialdehyde levels (lipid peroxidation product) and protein carbonyl content were also significantly decreased following fluoxetine treatment. Both these drugs when given alone to non-stressed animals did not alter basal levels of antioxidant defense components and oxidative stress markers significantly. Our findings suggest that the therapeutic efficacy of fluoxetine may be mediated, at least partially, via reversal of oxidative damage as demonstrated by protective enhancement of antioxidant status following a stress-induced decline. In addition, this study demonstrates important implications for pharmacological interventions targeting cellular antioxidants as a promising strategy for protecting against oxidative insults in stress-induced depression.

Stress and ageing interactions: A paradox in the context of shared etiological and physiopathological processes

Gerontology has made considerable progress in the understanding of the mechanisms underlying the ageing process and age-related neurodegenerative disorders. However, ways to improve quality of life in the elderly remain to be elucidated. It is now clear that stress and the ageing process share a number of underlying mechanisms bound in a very close, if not indissociable, relationship. The ageing process is regulated by the factors underlying the ability to adjust to stress, whilst stress has an influence on the life span and the quality of ageing. In addition, the ability to cope with stress in adulthood predicts life expectancy and quality of life at senescence. The ageing process and stress also share several common mechanisms, particularly in relation to the energy factor. Stress consumes energy and ageing may be considered as a cost of the energy expended to deal with the stressors to which the body is exposed throughout its lifetime. This suggests that the ageing process is associated with and/or a consequence of a long-lasting activation of the major stress responsive systems. However, despite common features, the interaction between stress and the ageing process gives rise to some paradoxes. Stress can either diminish or exacerbate the ageing process just as the ageing process can worsen or counter the effects of stress. There has been little attempt to understand how ageing and stress might interact to promote "successful" or pathological ageing. A key factor in this respect is the individual's ability to adapt to stress. Viewed from this angle, the quality of life of aged subjects may be improved through therapy designed to improve the tolerance to stress.

Mulberry leaves protect rat tissues from immobilization stress-induced inflammation

The ability of the antioxidants in the mulberry leaves to protect Sprague-Dawley rats from injuries caused by immobilization stress was studied as an indicator of the tissue bioavailability of antioxidants. Nitrite level, lipid peroxidation and total antioxidant activity (TAA) in the plasma and tissues were measured. There were hypertrophy of the adrenal glands and kidneys, significant increased levels of nitrite in the plasma and adrenal glands, elevated thiobarbituric acid reactive substances (TBARS) in the plasma, kidneys and spleen, and a reduction of TAA in the plasma, liver, adrenal glands, kidneys and spleen of the immobilized rats. Antioxidants in the mulberry leaf extract suppressed the increase of nitrite and TBARS. Adrenal glands appeared to be the target organ of the antioxidants in the leaf extract. The low dose mulberry antioxidants were more effective than pure rutin (4 mg/day) to protect the cells against inflammation and peroxidation induced by stress.

Effects of pyrrolidine dithiocarbamate on beta-amyloid (25–35)-induced inflammatory responses and memory deficits in the rat

It has been well established that neuroinflammation is involved in Alzheimer disease (AD) pathogenesis. Accumulation and aggregation of beta-amyloid (Abeta) peptide in the brains of patients with AD result in activation of glial cells which, in turn, initiates neuroinflammatory responses that involve reactive oxygen intermediates and release of inflammatory cytokines. In this study, bilateral intracerebroventricular (i.c.v.) injections of Abeta (25-35) in the rat resulted in impairment in learning and spatial memory and increased immunoreactive staining of AD-related neuropathological markers (Abeta, APP) and inflammatory mediators (OX-6, COX-2) in CA1 and dentate gyrus regions of the hippocampus. Pyrrolidine dithiocarbamate (PDTC) given intraperitoneally 30 min before Abeta injection and daily for 7 days postsurgery significantly prevented Abeta-induced neuropathological and neuroinflammatory responses, as well as the learning and spatial memory deficits. The potential of PDTC for reducing cognitive and neuropathological deficits may provide preliminary evidence for a new approach of AD treatment.