Gender-specific impact of brain-derived neurotrophic factor signaling on stress-induced depression-like behavior

Sustained expression of brain-derived neurotrophic factor is required for maintenance of dendritic spines and normal behavior

Brain-derived neurotrophic factor (BDNF) plays important roles in the development, maintenance, and plasticity of the mammalian forebrain. These functions include regulation of neuronal maturation and survival, axonal and dendritic arborization, synaptic efficacy, and modulation of complex behaviors including depression and spatial learning. Although analysis of mutant mice has helped establish essential developmental functions for BDNF, its requirement in the adult is less well documented. We have studied late-onset forebrain-specific BDNF knockout (CaMK-BDNF(KO)) mice, in which BDNF is lost primarily from the cortex and hippocampus in early adulthood, well after BDNF expression has begun in these structures. We found that although CaMK-BDNF(KO) mice grew at a normal rate and can survive more than a year, they had smaller brains than wild-type siblings. The CaMK-BDNF(KO) mice had generally normal behavior in tests for ataxia and anxiety, but displayed reduced spatial learning ability in the Morris water task and increased depression in the Porsolt swim test. These behavioral deficits were very similar to those we previously described in an early-onset forebrain-specific BDNF knockout. To identify an anatomical correlate of the abnormal behavior, we quantified dendritic spines in cortical neurons. The spine density of CaMK-BDNF(KO) mice was normal at P35, but by P84, there was a 30% reduction in spine density. The strong similarities we find between early- and late-onset BDNF knockouts suggest that BDNF signaling is required continuously in the CNS for the maintenance of some forebrain circuitry also affected by developmental BDNF depletion.

Brain-derived neurotrophic factor and neuropsychiatric disorders

Brain derived neurotrophic factor (BDNF) is the most prevalent growth factor in the central nervous system (CNS). It is essential for the development of the CNS and for neuronal plasticity. Because BDNF plays a crucial role in development and plasticity of the brain, it is widely implicated in psychiatric diseases. This review provides a summary of clinical and preclinical evidence for the involvement of this ubiquitous growth factor in major depressive disorder, schizophrenia, addiction, Rett syndrome, as well as other psychiatric and neurodevelopmental diseases. In addition, the review includes a discussion of the role of BDNF in the mechanism of action of pharmacological therapies currently used to treat these diseases, such antidepressants and antipsychotics. The review also covers a critique of experimental therapies such as BDNF mimetics and discusses the value of BDNF as a target for future drug development.

Low dietary or supplemental zinc is associated with depression symptoms among women, but not men, in a population-based epidemiological survey

BACKGROUND

Prior studies indicate that the biochemical alterations of depressive episodes result in decreased serum zinc concentrations. Given these findings, it is plausible that consistently low dietary zinc intakes contribute to depressive symptoms, yet epidemiological data are lacking. The authors tested the hypothesis that low zinc intake is associated with depressive symptoms using cross-sectional data from the population-based Boston Area Community Health survey (2002-2005).

METHODS

Dietary and supplement use data were collected by validated food frequency questionnaire. Current depressive symptoms were assessed by the abridged validated Center for Epidemiologic Studies Depression scale and analyzed using multivariate logistic regression, adjusting for sociodemographic, health and lifestyle characteristics.

RESULTS

Results showed an interaction (P=0.03) with gender, whereby zinc was associated with depressive symptoms in women (N=2163), but not men (N=1545). Women with low dietary or supplemental zinc intake were more likely to have depressive symptoms (e.g., dietary zinc quartile 1 vs. 4, OR=1.76, 95% CI: 1.26, 2.45; P-trend=0.004; supplemental zinc P-trend=0.03). Associations were stronger among women using antidepressant medications (e.g., total zinc OR=4.75, 95% CI: 1.98, 11.4; P-trend=0.0005).

LIMITATIONS

The cross-sectional, observational nature of the study leaves uncertain whether the observed associations represent actual causal relationships between zinc intake and depressive symptoms.

CONCLUSIONS

These findings suggest: (1) gender-specific pathophysiological mechanisms of depression, (2) inadequate dietary zinc intake contributes to depressive symptoms in women, and (3) supplemental zinc is a beneficial adjunct to antidepressant therapy in women. Additional research on both men and women is needed to verify these novel findings. If confirmed by other studies, the potential importance of adequate zinc intake is underscored by the recognized limitations of pharmacotherapy for depression.

Signaling pathways underlying the pathophysiology and treatment of depression: novel mechanisms for rapid-acting agents

Basic and clinical studies demonstrate that stress and depression are associated with atrophy and loss of neurons and glia, which contribute to the decreased size and function of limbic brain regions that control mood and depression, including the prefrontal cortex and hippocampus. Here, we review findings that suggest that opposing effects of stress and/or depression and antidepressants on neurotrophic factor expression and signaling partly explain these effects. We also discuss recent reports that suggest a possible role for glycogen synthase kinase 3 and upstream wingless (Wnt)-frizzled (Fz) signaling pathways in mood disorders. New studies also demonstrate that the rapid antidepressant actions of NMDA receptor antagonists are associated with activation of glutamate transmission and induction of synaptogenesis, providing novel targets for a new generation of fast-acting, more efficacious therapeutic agents.

Brain-derived neurotrophic factor in post-partum depressive mothers

Postpartum depression (PPD) is the most common psychiatric complication observed in women after they give birth. Some women are particularly sensitive to hormonal changes, starting in early menarche, thus increasing their vulnerability to psychological stressing agents that are triggered by environmental and physiological factors throughout their lives. Decreased serum brain-derived neurotrophic factor (BDNF) levels have been associated to different neuropsychiatric conditions and BDNF has been considered as a candidate marker for such dysfunctions. The goal of this study was to compare the levels of BDNF between mothers who suffer from PPD and healthy control mothers as well as to searching for associations between BDNF levels and the severity of PPD. This is a case-control study including 36 mothers with PPD and 36 healthy control mothers. PPD was defined according to the Beck Depression Inventory (BDI). Serum BDNF was assayed with the sandwich ELISA method.

RESULTS

Serum levels of BDNF were significantly lower in women with PPD than in control mothers (P ≤ 0.03). A significant negative correlation between BDI score and serum BDNF levels was observed (P ≤ 0.02 and r = -0.29). Our study demonstrated that low BDNF levels are associated with PPD. This result point out to the potential usage of BDNF in the screening of PPD, which could promote early treatment and, therefore, reduce the burden to the PPD women and to the health system.

Chronic variable physical stress during the peripubertal-juvenile period causes differential depressive and anxiogenic effects in the novelty-seeking phenotype: functional implications for hippocampal and amygdalar brain-derived neurotrophic factor and the mossy fibre plasticity

Experimentally naive rats show variance in their locomotor reactivity to novelty, some displaying higher (HR) while others displaying lower (LR) reactivity, associated with vulnerability to stress. We employed a chronic variable physical stress regimen incorporating intermittent and random exposures of physical stressors or control handling during the peripubertal-juvenile period to assess interactions between stress and the LRHR phenotype in depressive- and anxiety-like behaviors on the forced swim and social interaction tests, respectively. A decrease in immobility in the forced swim test along with a decrease in social contact in the social interaction test were observed in the juvenile HRs, coupled with increases in brain-derived neurotrophic factor (BDNF) mRNA in the hippocampus and in the basolateral amygdala with chronic variable physical stress. In contrast, an increase in immobility in the forced swim test and a decrease in social contact was observed in the LR counterparts coupled with an increase in the BDNF mRNA in the basolateral amygdala following chronic variable physical stress. Furthermore, chronic physical stress led to increased H3 and H4 acetylation at the P2 and P4 promoters of the hippocampal BDNF gene in the HR rats that is associated with increased suprapyramidal mossy fibre (SP-MF) terminal field volume. In contrast, chronic variable physical stress led to decreased H4 acetylation at the P4 promoter, associated with decreased SP-MF volume in the LR rats. These findings show dissociation in depressive- and anxiety-like behaviors following chronic variable physical stress in the juvenile HR animals that may be mediated by increased levels of BDNF in the hippocampus and in the amygdala, respectively. Moreover, chronic variable physical stress during the peripubertal-juvenile period results in opposite effects in depressive-like behavior in the LRHR rats by way of inducing differential epigenetic regulation of the hippocampal BDNF gene that, in turn, may mediate mossy fibre sprouting.

Alcohol induced depressive-like behavior is associated with a reduction in hippocampal BDNF

Strong positive correlation between depression and alcoholism is evident in epidemiological reports. However, a causal relationship for this co-morbidity has not been established. We have observed that chronic daily exposure to a relatively high dose of alcohol can induce depressive-like behavior in rats and that pretreatment with nomifensine or imipramine can block the "depressogenic" effects of alcohol. Since brain derived neurotrophic factor (BDNF) is considered to play an important role in depressive-like behaviors and its elevation, particularly in the hippocampus, appears to be critical for the action of many antidepressants, we hypothesized that: 1. WKY rats, a putative animal model of depression, will show a lower hippocampal BDNF compared to their control Wistar rats, 2. Alcohol-induced depressive like behavior will be associated with a significant decrease in hippocampal BDNF and 3. Treatments with antidepressants will normalize hippocampal BDNF. These postulates were verified by measuring hippocampal BDNF in Wistar and WKY rats at baseline, following chronic (10 day) treatment with alcohol and combination of alcohol with nomifensine or imipramine. Alcohol was administered via inhalation chamber (3 h/day) such that a blood alcohol level of approximately 150 mg% was achieved. Nomifensine (10 mg/kg) or imipramine (10 mg/kg) was administered i.p. daily immediately after alcohol exposure. BDNF was measured by standard ELISA kit. The results support a role for central BDNF in depressogenic effects of alcohol and antidepressant effects of nomifensine and imipramine. Moreover, depression per se as manifested in WKY rats may be associated with a reduction in hippocampal BDNF.

Effects of BDNF polymorphisms on brain function and behavior in health and disease

Brain-derived neurotrophic factor (BDNF), the most abundant neurotrophin in the brain, serves an important role during brain development and in synaptic plasticity. Given its pleiotropic effects in the central nervous system, BDNF has been implicated in cognitive function and personality development as well as the pathogenesis of various psychiatric disorders. Thus, BDNF is considered an attractive candidate gene for the study of healthy and diseased brain function and behaviors. Over the past decade, many studies have tested BDNF genetic association, particularly its functional Val66Met polymorphism, with psychiatric diseases, personality disorders, and cognitive function. Although many reports indicated a possible role for BDNF genetic effects in mental problems or brain function, other reports were unable to replicate the findings. The conflicting results in BDNF genetic studies may result from confounding factors such as age, gender, other environmental factors, sample size, ethnicity and phenotype assessment. Future studies with more homogenous populations, well-controlled confounding factors, and well-defined phenotypes are needed to clarify the BDNF genetic effects on mental diseases and human behaviors.

Enriched environment treatment reverses depression-like behavior and restores reduced hippocampal neurogenesis and protein levels of brain-derived neurotrophic factor in mice lacking its expression through promoter IV

Promoter IV-driven expression of brain-derived neurotrophic factor (BDNF), a major neuronal growth factor, is implicated in the pathophysiology of major depression. We previously reported that mice lacking expression of BDNF through promoter IV (BDNF-KIV mice) exhibit a depression-like phenotype. Here, we examined whether the depression-like phenotype and decreased levels of BDNF because of promoter IV deficit could be rescued by enriched environment (EE) treatment, a potential antidepressant intervention. Three weeks of EE treatment rescued depression-like behavior of BDNF-KIV mice as assessed by the tail suspension test, open-field test and sucrose preference test. EE treatment also increased BDNF transcripts driven by multiple endogenous promoters and restored BDNF protein levels in the hippocampus (HIP) of BDNF-KIV mice. Further, we investigated adult hippocampal neurogenesis as a possible cellular mechanism underlying the depression-like behavior and its recovery in BDNF-KIV mice. We found that the number of surviving progenitors and their dendritic length in the dentate gyrus of the HIP were reduced in BDNF-KIV mice compared with the control wild-type mice. EE treatment restored the reduction in cell survival and dendritic length and increased cell proliferation in BDNF-KIV mice. In conclusion, this study demonstrated that EE rescued depression-like behavior, decreased BDNF levels and defective neurogenesis in the HIP caused by lack of promoter IV-driven BDNF expression. These results suggest that decreased BDNF levels because of one impaired promoter can be compensated by other BDNF promoters and that BDNF levels may be one of the key factors regulating depression and antidepressant effects through hippocampal neurogenesis.

Working memory deficits, increased anxiety-like traits, and seizure susceptibility in BDNF overexpressing mice

BDNF regulates components of cognitive processes and has been implicated in psychiatric disorders. Here we report that genetic overexpression of the BDNF mature isoform (BDNF-tg) in female mice impaired working memory functions while sparing components of fear conditioning. BDNF-tg mice also displayed reduced breeding efficiency, higher anxiety-like scores, high self-grooming, impaired prepulse inhibition, and higher susceptibility to seizures when placed in a new empty cage, as compared with wild-type (WT) littermate controls. Control measures of general health, locomotor activity, motor coordination, depression-related behaviors, and sociability did not differ between genotypes. The present findings, indicating detrimental effects of life-long increased BDNF in mice, may inform human studies evaluating the role of BDNF functional genetic variations on cognitive abilities and vulnerability to psychiatric disorders.

Prolonged depression-like behavior caused by immune challenge: influence of mouse strain and social environment

Immune challenge by bacterial lipopolysaccharide (LPS) causes short-term behavioral changes indicative of depression. The present study sought to explore whether LPS is able to induce long-term changes in depression-related behavior and whether such an effect depends on mouse strain and social context. LPS (0.83 mg/kg) or vehicle was administered intraperitoneally to female CD1 and C57BL/6 mice that were housed singly or in groups of 4. Depression-like behavior was assessed with the forced swim test (FST) 1 and 28 days post-treatment. Group-housed CD1 mice exhibited depression-like behavior 1 day post-LPS, an effect that leveled off during the subsequent 28 days, while the behavior of singly housed CD1 mice was little affected. In contrast, singly housed C57BL/6 mice responded to LPS with an increase in depression-like behavior that was maintained for 4 weeks post-treatment and confirmed by the sucrose preference test. Group-housed C57BL/6 mice likewise displayed an increased depression-like behavior 4 weeks post-treatment. The behavioral changes induced by LPS in C57BL/6 mice were associated with a particularly pronounced rise of interleukin-6 in blood plasma within 1 day post-treatment and with changes in the dynamics of the corticosterone response to the FST. The current data demonstrate that immune challenge with LPS is able to induce prolonged depression-like behavior, an effect that depends on genetic background (strain). The discovery of an experimental model of long-term depression-like behavior after acute immune challenge is of relevance to the analysis of the epigenetic and pathophysiologic mechanisms of immune system-related affective disorders.

The prefrontal-limbic network in depression: Modulation by hypothalamus, basal ganglia and midbrain

The anterior cingulate cortex, amygdala and hippocampus form part of an interconnected prefrontal neocortical and limbic archicortical network that is dysregulated in major depressive disorders (MDD). Modulation of this prefrontal-limbic network (PLN) is principally through the hypothalamus, basal ganglia and midbrain. Here the likely mechanisms by which these modulations are affected are described and the implications of their failure for depression associated with suicidal diathesis, late-life and psychoses discussed.

Determinants of serum brain-derived neurotrophic factor

BACKGROUND

Brain-derived neurotrophic factor (BDNF) belongs to the neurotrophin family of growth factors and affects the survival and plasticity of neurons in the adult central nervous system. The high correlation between cortical and serum BDNF levels has led to many human studies on BDNF levels in various populations, however knowledge about determinants that influence BDNF is lacking.

AIMS

To gain insight into the factors that influence BDNF levels in humans.

METHODS

In 1168 people aged 18 through 65, free of antidepressants and current psychiatric disease, from the Netherlands study of depression and anxiety four categories of determinants (sampling, sociodemographics, lifestyle indicators and diseases) were measured as well as BDNF level. We used univariate analyses as well as multivariate linear regression analyses in particular to determine which of the possible determinants significantly influenced serum BDNF levels.

RESULTS

The mean BDNF level was 8.98ng/ml (SD 3.1ng/ml) with a range from 1.56ng/ml through 18.50ng/ml. Our final multivariate regression analysis revealed that a non-fasting state of blood draw (β=-.067; p=.019), later measurement (β=-.065; p=.022), longer sample storage (β=-.082; p=.004) and being a binge drinker (β=-.063; p=.035) all resulted in attenuated BDNF levels. This was in contrast to smoking (β=.098; p=.001) and living in an urban area (β=.109; p<.001), which resulted in increased BDNF levels. Moreover we found that older subjects also had higher BDNF levels, but this only applied to women (β=.226; p<.001).

CONCLUSIONS

Future studies on serum levels of BDNF in humans should correct for the time of blood withdrawal, storage, urbanicity, age, sex, smoking status and food and alcohol intake.

Long-term ovariectomy enhances anxiety and depressive-like behaviors in mice submitted to chronic unpredictable stress

Ovarian hormones exert anti-depressive and anxiolytic actions. In this study we have analyzed the effects of ovariectomy on the development of anxiety and depression-like behaviors and on cell proliferation in the hippocampus of mice submitted to chronic unpredictable stress. Animals submitted to stress 4 months after ovariectomy showed a significant increase in immobility behavior in the forced swimming test compared to animals submitted to stress 2 weeks after ovariectomy. In addition, long-term ovariectomy resulted in a significant decrease on the time spent in the open arms in the elevated plus-maze test compared to control animals. Stress did not significantly affect cell proliferation in the hilus of the dentate gyrus. However, ovariectomy resulted in a significant decrease in cell proliferation. These results indicate that long-term deprivation of ovarian hormones enhances the effect of chronic unpredictable stress on depressive- and anxiety-like behaviors in mice. Therefore, a prolonged deprivation of ovarian hormones may represent a risk factor for the development of depressive and anxiety symptoms after the exposure to stressful experiences.

Serum and plasma BDNF levels in major depression: a replication study and meta-analyses

OBJECTIVES

Alterations of BDNF signalling in major depression (MD) are supported by studies demonstrating decreased levels of the neurotrophin serum and plasma content in MD patients. We conducted a replication study and we performed two meta-analyses on studies analysing serum and plasma BDNF levels in MD patients.

METHODS

The samples were composed by 489 patients/483 controls for the meta-analysis on serum and by 161 patients/211 controls for that on plasma levels. We performed also subgroup analyses to examine whether the decrease in BDNF levels in MD was influenced by gender.

RESULTS

In the replication study we found decreased serum BDNF levels in MD patients (P<0.01) and we demonstrated that is down-regulated the mature form of the neurotrophin (mBDNF). No significant difference was evidenced for plasma BDNF levels. The meta-analyses showed a reduction of both BDNF serum (P<0.0001) and plasma levels (P=0.02) in MD. No difference in the effect size on serum BDNF was observed between males and females (P=0.18).

CONCLUSIONS

In conclusion, our results provide evidence of peripheral BDNF alteration in MD and support the rationale for further investigation aiming to the identification of biomarkers for differential diagnosis and personalization of therapies in this disorder.

Altering BDNF expression by genetics and/or environment: impact for emotional and depression-like behaviour in laboratory mice

According to the "neurotrophin hypothesis", brain-derived neurotrophic factor (BDNF) is an important candidate gene in depression. Moreover, environmental stress is known to represent a risk factor in the pathophysiology and treatment of this disease. To elucidate, whether changes of BDNF availability signify cause or consequence of depressive-like alterations, it is essential to look for endophenotypes under distinct genetic conditions (e.g. altered BDNF expression). Furthermore it is crucial to examine environment-driven BDNF regulation and its effect on depressive-linked features. Consequently, gene × environment studies investigating prospective genetic mouse models of depression in different environmental contexts become increasingly important. The present review summarizes recent findings in BDNF-mutant mice, which have been controversially discussed as models of depression and anxiety. It furthermore illustrates the potential of environment to serve as naturalistic stressor with the potential to modulate the phenotype in wildtype and mutant mice. Moreover, environment may exert protective effects by regulating BDNF levels as attributed to "environmental enrichment". The effect of this beneficial condition will also be discussed with regard to probable "curative/therapeutic" approaches.

Lack of promoter IV-driven BDNF transcription results in depression-like behavior

Transcription of Bdnf is controlled by multiple promoters, in which promoter IV contributes significantly to activity-dependent Bdnf transcription. We have generated promoter IV mutant mice [brain-derived neurotrophic factor (BDNF)-KIV] in which promoter IV-driven expression of BDNF is selectively disrupted by inserting a green fluorescent protein (GFP)-STOP cassette within the Bdnf exon IV locus. BDNF-KIV animals exhibited depression-like behavior as shown by the tail suspension test (TST), sucrose preference test (SPT) and learned helplessness test (LHT). In addition, BDNF-KIV mice showed reduced activity in the open field test (OFT) and reduced food intake in the novelty-suppressed feeding test (NSFT). The mutant mice did not display anxiety-like behavior in the light and dark box test and elevated plus maze tests. Interestingly, the mutant mice showed defective response inhibition in the passive avoidance test (PAT) even though their learning ability was intact when measured with the active avoidance test (AAT). These results suggest that promoter IV-dependent BDNF expression plays a critical role in the control of mood-related behaviors. This is the first study that directly addressed the effects of endogenous promoter-driven expression of BDNF in depression-like behavior.

Modeling the positive symptoms of schizophrenia in genetically modified mice: pharmacology and methodology aspects

In recent years, there have been huge advances in the use of genetically modified mice to study pathophysiological mechanisms involved in schizophrenia. This has allowed rapid progress in our understanding of the role of several proposed gene mechanisms in schizophrenia, and yet this research has also revealed how much still remains unresolved. Behavioral studies in genetically modified mice are reviewed with special emphasis on modeling psychotic-like behavior. I will particularly focus on observations on locomotor hyperactivity and disruptions of prepulse inhibition (PPI). Recommendations are included to address pharmacological and methodological aspects in future studies. Mouse models of dopaminergic and glutamatergic dysfunction are then discussed, reflecting the most important and widely studied neurotransmitter systems in schizophrenia. Subsequently, psychosis-like behavior in mice with modifications in the most widely studied schizophrenia susceptibility genes is reviewed. Taken together, the available studies reveal a wealth of available data which have already provided crucial new insight and mechanistic clues which could lead to new treatments or even prevention strategies for schizophrenia.

BDNF moderates early environmental risk factors for anxiety in mouse

Anxiety is known to be influenced by both adverse childhood experiences and genetic susceptibility factors. A polymorphism in the brain-derived neurotrophic factor (BDNF) gene modulates the association between adverse early experiences and risk for anxiety and depression in adulthood. An animal model of this gene-by-environment risk factor is lacking. Using two different early environmental manipulations, we found that a heterozygous null mutation in the mouse BDNF gene moderated the long-term effect of maternal care on innate anxiety behavior. Although changes in maternal care were associated with mild changes in anxiety in wild-type mice, this effect was magnified in heterozygous null BDNF mice with high- and low-maternal care associated with low and high levels, respectively, of avoidance behavior as measured in the open field and elevated plus maze tests. These data argue for an increased sensitivity to early environmental influences of mice with reduced BDNF function and support the important role of this neurotrophic factor in the developmental plasticity of brain circuits controlling anxiety.

Effects of estradiol on learned helplessness and associated remodeling of hippocampal spine synapses in female rats

BACKGROUND

Despite the fact that women are twice as likely to develop depression as men, our understanding of depression neurobiology in female subjects is limited. We have recently reported in male rats that development of helpless behavior is associated with a severe loss of hippocampal spine synapses, which is reversed by treatment with the antidepressant desipramine. Considering that estradiol has a hippocampal synaptogenic effect similar to those of antidepressants, the presence of estradiol during the female reproductive life might influence behavioral and synaptic responses to stress and depression.

METHODS

With electron microscopic stereology, we analyzed hippocampal spine synapses in association with helpless behavior in ovariectomized female rats (n = 70), under different conditions of estradiol exposure.

RESULTS

Stress induced an acute and persistent loss of hippocampal spine synapses, whereas subchronic treatment with desipramine reversed the stress-induced synaptic loss. Estradiol supplementation given either before stress or before escape testing of nonstressed animals increased the number of hippocampal spine synapses. Correlation analysis demonstrated a statistically significant negative correlation between the severity of helpless behavior and hippocampal spine synapse numbers.

CONCLUSIONS

These findings suggest that hippocampal spine synapse remodeling might be a critical factor underlying learned helplessness and, possibly, the neurobiology of depression.

Peony glycosides produce antidepressant-like action in mice exposed to chronic unpredictable mild stress: effects on hypothalamic-pituitary-adrenal function and brain-derived neurotrophic factor

The root part of Paeonia lactiflora Pall. (Ranunculaceae), commonly known as peony, is a commonly used Chinese herb for the treatment of depression-like disorders. Previous studies in our laboratory have demonstrated that total glycosides of peony (TGP) produced antidepressant-like action in various mouse models of behavioral despair. The present study aimed to examine whether TGP could affect the chronic unpredictable mild stress (CUMS)-induced depression in mice. The mechanism(s) underlying the antidepressant-like action was investigated by measuring serum corticosterone level, glucocorticoid receptor (GR) and brain-derived neurotrophic factor (BDNF) mRNA levels in brain tissues. CUMS, being lasted for 6 weeks, caused depression-like behavior in mice, as indicated by the significant decrease in sucrose consumption and increase in immobility time in the forced swim test. Whereas serum corticosterone level was significantly increased in mice exposed to CUMS, expressions of GR mRNA in hippocampus, and BDNF mRNA in hippocampus and frontal cortex, were decreased in CUMS-treated mice. Daily intragastric administration of TGP (80 or 160 mg/kg/day) during the six weeks of CUMS significantly suppressed behavioral and biochemical changes induced by CUMS. The results suggest that the antidepressant-like action of TPG is likely mediated by modulating the function of hypothalamic-pituitary-adrenal axis and increasing the expression of BDNF in brain tissues.

Rapid antidepressant effects of sleep deprivation therapy correlates with serum BDNF changes in major depression

Recent reports have suggested that brain-derived neurotrophic factor (BDNF) levels are reduced in individuals suffering major depressive disorder and these levels normalize following antidepressant treatment. Various antidepressants and electroconvulsive therapy are shown to have a positive effect on brain-derived neurotrophic factor levels in depressive patients. The aim of this study was to assess the effect of total sleep deprivation therapy on BDNF levels in major depressive patients. Patients were assigned to two treatment groups which consisted of 22 patients in the sertraline group and 19 patients in the total sleep deprivation plus sertraline group. Patients in the sleep deprivation group were treated with three total sleep deprivations in the first week of their treatment and received sertraline. Patients in sertraline group received only sertraline. BDNF levels were measured in the two treatment groups at baseline, 7th, 14th, and 42nd days. Patients were also evaluated using the Hamilton Rating Scale for Depression (HAM-D). A control group, consisting of 33 healthy volunteers had total sleep deprivation, BDNF levels and depression measured at baseline and after the total sleep deprivation. Results showed that serum BDNF levels were significantly lower at baseline in both treatment groups compared to controls. Decreased levels of BDNF were also negatively correlated with HAM-D scores. First single sleep deprivation and a series of three sleep deprivations accelerated the treatment response that significantly decreased HAM-D scores and increased BDNF levels. Total sleep deprivation and sertraline therapy is introduced to correlate with the rapid treatment response and BDNF changes in this study.