Effects of fluoxetine and venlafaxine on serum brain derived neurotrophic factor levels in depressed patients

Background

Several studies demonstrated that depressed patients had low serum BDNF levels which correlated with the severity of their depression, and antidepressant treatment increases levels of serum BDNF in depressed patients. It was speculated that agents acting on both noradrenergic and serotonergic transporters might have a greater influence on BDNF levels. The aim of our study was to determine effects of venlafaxine vs. fluoxetine on serum BDNF levels in depressive patients.

Methods

Forty-three patients diagnosed as major depressive disorder according to DSM-IV are included in the study. Forty-three patients were randomized to take fluoxetine (22 cases) or venlafaxine (21 cases). Serum levels of BDNF were measured by ELISA at baseline and 6 weeks after the start of treatment.

Results

Baseline levels of BDNF were not significantly different between the patient group and the controls. But male patients and the male controls showed statistical differences with respect to baseline BDNF levels. BDNF levels of the patient group did not change with treatment. Yet, the increase of BDNF levels was close to statistically significant in the fluoxetine group, whereas not significant in the venlafaxine group. There were no significant differences in baseline and 6th week BDNF levels between the responders and the non-responders.

Conclusion

Further studies controlling for a wide variety of confounding variables are needed, which may help to reach a clear conclusion about the potential of BDNF as a biomarker for depression or as a predictor of antidepressant efficacy.     

Changes in BDNF serum levels in patients with major depression disorder (MDD) after 6 months treatment with sertraline, escitalopram, or venlafaxine

Recent studies have implicated brain-derived neurotrophic factor (BDNF) in the pathophysiology of depression and the activity of antidepressant drugs. Serum BDNF levels are lower in depressed patients, and increase in response to antidepressant medication. However, how BDNF responds to different classes of antidepressant drugs is unknown. We assessed serum BDNF levels in 21 patients with major depressive episode treated with sertraline, escitalopram, or venlafaxine and 20 healthy controls. Serum samples were collected between 10 a.m. and 12 p.m. at baseline, 5 weeks, and 6 months of treatment. BDNF levels were measured via immunoassay. The severity of symptoms and response to treatment were assessed by the Hamilton rating scales for depression (HRSD). Baseline serum BDNF levels were significantly lower in depressed patients compared to controls. Sertraline increased BDNF levels after 5 weeks and 6 months of treatment. Venlafaxine increased BDNF levels only after 6 months. Escitalopram did not affect BDNF levels at either time point. A significant negative association was found between percentage increase in BDNF levels and percentage decreased in HRSD scores after 6 months of treatment. In conclusion, these results suggest that different antidepressant drugs have variable effects on serum BDNF levels. This is true even though the three different drugs were equally effective in relieving symptoms of depression and anxiety.     

The effect of chronic antidepressant treatment on serum brain-derived neurotrophic factor levels in depressed patients: a preliminary study

Recent studies suggested a role of brain-derived neurotrophic factor (BDNF) in depression. While BDNF levels are lower in depressed patients, antidepressant treatment increases serum BDNF levels of depressed patients. Our study aims to test the effect of chronic venlafaxine treatment on serum BDNF levels in patients with a major depressive disorder. Ten patients diagnosed as major depressive disorder according to DSM-IV are included in the study. Two of the patients had their first episode and were drug-naive, the other eight patients were drug-free for at least 4 weeks. The severity of depression was assessed with Hamilton Depression Rating Scale (HDRS). The control group consisted of ten age- and sex-matched subjects without any psychiatric disorder. Blood samples were collected at the baseline and after 12 weeks of antidepressant treatment (during remission). At the baseline the mean serum BDNF level was 17.9+/-9.1 ng/ml and the mean HDRS score was 23.2+/-4.6. Serum BDNF levels of the study group were significantly lower than in the control group (31.6+/-8.6 ng/ml). At the end of the study, the mean serum BDNF level was 34.6+/-7.1 ng/ml whereas the mean HDRS score was 8.2+/-3.9. From the baseline to the remission after 12 weeks of treatment, the increase in serum BDNF level and the decrease in HDRS score were statistically significant, respectively. When we compared the serum BDNF level of depressed patients at remission to that of the controls, there was no statistically significant difference. This study shows that venlafaxine treatment of depression improves serum BDNF level which may be considered as a nonspecific peripheral marker of depression.     

抑郁症患者治疗前后血清脑源性神经营养因子水平变化及相关因素分析

目的 探讨抑郁症患者血清脑源性神经营养因子(BDNF)水平及其变化与负性生活事件、抑郁症发病及治疗效应的关系.方法 采用横断面的病例-对照及前瞻性自身对照设计.对所有抑郁症患者给予抗抑郁治疗(包括抗抑郁药和改良电抽搐治疗),并随访治疗8周;采用酶联免疫吸附法测定63例抑郁症患者(抑郁症组)治疗前和治疗第2,4,8周末及80名正常对照(以下简称对照组)血清BDNF水平,并评定汉密尔顿抑郁量表(HAMD)和生活事件量表.结果 抑郁症组治疗前血清BDNF水平[(24±14)μg/L]显著低于对照组[(36±15)μg/L](t=-4.863,P=0.000),并与病前1年负性生活事件刺激值、治疗前HAMD总分均显著负相关(r=-0.331,P=0.008;r=-0.343,P=0.006),而后两者有相互正相关(r=0.292,P=0.020);治疗第2周末血清BDNF水平仍显著低于对照绢(t=-5.990,P=0.000),并与其抑郁症状严重度平行负相关(r=-0.269,P=0.033),且其血清BDNF增加率与HAMD减分率平行正相关(r=0.252,P=0.047);治疗第4,8周末血清BDNF水平均显著高于治疗前(经ISD检验,P=0.000;P=0.005),与对照组的差异均无统计学意义(P均＞0.05).治疗第2,4,8周末HAMD总分渐减并均低于治疗前(P均=0.001),且其HAMD平均减分率渐升(分别为40%,66%和74%).结论血清BDNF低下与负性生活事件、抑郁症发病密切相关,血清BDNF升高可能为抗抑郁治疗临床疗效的重要指标之一.     

Physical activity-antidepressant treatment combination: impact on brain-derived neurotrophic factor and behavior in an animal model

The mechanism of antidepressant action, at the cellular level, is not clearly understood. It has been reported that chronic antidepressant treatment leads to an up-regulation of brain-derived neurotrophic factor (BDNF) mRNA levels in the hippocampus, and that physical activity (voluntary running) enhances this effect. We wished to investigate whether BDNF expression brought about by these interventions may overcome deficits caused by acute stress, and might impact behavior in an animal model. In this report, we have tested the hypothesis that the combination of the antidepressant, tranylcypromine, and physical exercise could lead to decreased neurotrophin deficits and enhanced swimming time in animals that have been forced to swim in an inescapable water tank. Rats were either treated with tranylcypromine, engaged in voluntary running, or both for one week. After these treatments, the animals underwent a two-day forced swimming procedure. BDNF mRNA levels were significantly depressed in untreated animals subjected to forced swimming. Animals that either underwent prior activity or received antidepressant showed BDNF mRNA levels restored to baseline. Animals receiving the combined intervention showed an increase in hippocampal BDNF mRNA well above baseline. Swimming time during a five-minute test was significantly enhanced in animals receiving the combined intervention over untreated animals. Swimming time was not significantly enhanced over that of animals receiving antidepressant alone, however. Enhanced swimming time correlated with increased levels of BDNF mRNA in one hippocampal sub-region (CA4-hilus). These results suggest that the combination of exercise and antidepressant treatment may have significant neurochemical, and possibly behavioral, effects. In addition, these results support the possibility that the enhancement of BDNF expression may be an important element in the clinical response to antidepressant treatment. The induction of BDNF expression by activity/pharmacological treatment combinations could represent an important intervention for further study, to potentially improve depression treatment and management.     

Regulation of brain-derived neurotrophic factor (BDNF) in the chronic unpredictable stress rat model and the effects of chronic antidepressant treatment

Chronic unpredictable stress (CUS) is a widely used animal model of depression. The present study was undertaken to investigate behavioral, physiological and molecular effects of CUS and/or chronic antidepressant treatment (venlafaxine or imipramine) in the same set of animals. Anhedonia, a core symptom of depression, was assessed by measuring consumption of a palatable solution. Exposure to CUS reduced intake of a palatable solution and this effect was prevented by chronic antidepressant treatment. Moreover, chronic antidepressant treatment decreased depressive-like behavior in a modified forced swim test in stressed rats. Present evidence suggests a role for brain-derived neurotrophic factor (BDNF) in depression. BDNF mRNA levels in the ventral and dorsal hippocampus were assessed by in situ hybridization. Exposure to CUS was not correlated with a decrease but rather with an increase in BDNF mRNA expression in both the dentate gyrus of the dorsal hippocampus and the CA3 region of the ventral hippocampus indicating that there is no simple link between depression-like behaviors per se and brain BDNF levels in rats. However, a significant increase in BDNF mRNA levels in the dentate gyrus of the dorsal hippocampus correlated with chronic antidepressant treatment emphasizing a role for BDNF in the mechanisms underlying antidepressant activity.     

Partial normalization of serum brain-derived neurotrophic factor in remitted patients after a major depressive episode

We had previously reported decreased serum brain-derived neurotrophic factor (BDNF) levels in depressed patients. In the present study, we tested the hypothesis that antidepressant treatment would normalize serum BDNF levels, at least in a subgroup of patients. Major depressed patients (15 females and 11 males) diagnosed according to DSM-IV criteria and healthy controls (13 females and 13 males) participated in this study. Serum BDNF was assayed with the ELISA method for depressed and remitted patients and the severity of depression was evaluated with the Montgomery-Asberg Depression Rating Scale. An analysis of variance showed that treatment had an effect [F(1, 24) = 4.46, p = 0.045] on the normalization of serum BDNF levels. We also found a correlation between the severity of depression (r = 0.51, p = 0.008), the pretreatment BDNF levels (r = 0.62, p = 0.001) and the difference in serum BDNF levels after antidepressant treatment. These results suggest that antidepressant treatment has a positive effect on serum BDNF levels and support the hypothesis of neurotrophic factor involvement in affective disorders.     

Brain‐derived neurotrophic factor as a biomarker for mood disorders: An historical overview and future directions

Mood disorders, such as major depressive disorder (MDD) and bipolar disorder (BPD), are the most prevalent psychiatric conditions, and are also among the most severe and debilitating. However, the precise neurobiology underlying these disorders is currently unknown. One way to combat these disorders is to discover novel biomarkers for them. The development of such biomarkers will aid both in the diagnosis of mood disorders and in the development of effective psychiatric medications to treat them. A number of preclinical studies have suggested that the brain‐derived neurotrophic factor (BDNF) plays an important role in the pathophysiology of MDD. In 2003, we reported that serum levels of BDNF in antidepressant‐naive patients with MDD were significantly lower than those of patients medicated with antidepressants and normal controls, and that serum BDNF levels were negatively correlated with the severity of depression. Additionally, we found that decreased serum levels of BDNF in antidepressant‐naive patients recovered to normal levels associated with the recovery of depression after treatment with antidepressant medication. This review article will provide an historical overview of the role played by BDNF in the pathophysiology of mood disorders and in the mechanism of action of therapeutic agents. Particular focus will be given to the potential use of BDNF as a biomarker for mood disorders. BDNF is initially synthesized as a precursor protein proBDNF, and then proBDNF is proteolytically cleaved to the mature BDNF. Finally, future perspectives on the use of proBDNF as a novel biomarker for mood disorders will be discussed.     

Neurotrophic factors and their role in the pathogenesis of affective disorders

Neurotrophic factors are a group of proteins with a similar structure (The regulation of neuronal plasticity and neuron protection are some of their biological functions). The group of neurotrophic factors consists of: growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3) and neurotrophin 4/5 (NT-4/5). BDNF is the most important neurotrophin from the affective disorders point of view. Preclinical and clinical studies of altered BDNF expression during chronic stress and increased BDNF activity during antidepressant treatment, confirm the role of BDNF in the pathogenesis of depression. Studies on animal models point to the antidepressant effect of BDNF, similar to long-term antidepressant treatment. The intracellular mechanisms mediated by this neurotrophic factor are connected with signal transduction pathways in cells (mainly mitogen-activated protein kinase cascade and cyclic adenosine 3',5'-monophosphate cascade). The BDNF serum level studies suggest a correlation between the BDNF expression in the central nervous system and its serum levels, what could make BDNF levels specific markers of depression. The molecular genetic studies focus on associations between BDNF gene polymorphisms and bipolar disorder or cognitive functioning disturbances. The novel pathogenetic theories of depression based on neuronal plasticity (Duman et al.) and disturbances in neurogenesis (Kempermann and Kronenberg) can be a kind of recapitulation of research on the role of neurotrophins in depression. However many issues related to the role of neurotrophic factors in affective disorders are still unclear and determine areas of future scientific interests in this field.     

Brain-derived neurotrophic factor (BDNF) serum level in women with first-episode depression,correlation with clinical and metabolic parameters

Background: Brain-derived neurotrophic factor (BDNF) influences neuron differentiation during development, as well as the synaptic plasticity and neuron survival in adulthood. BDNF has been implicated in the pathogenesis of psychiatric disorders and its serum level is a potential biomarker for depression. The aim of this study was to examine serum levels of BDNF in first-episode depression and its correlation with clinical and metabolic parameters.

Materials and methods: The study was performed on a group of 60 women: 30 diagnosed with a first-episode of depression and 30 healthy controls. 17-Item Hamilton Depression Rating Scale (HDRS-17) was used to assess the severity of depression. Patients were randomly chosen for treatment with sertraline or venlafaxine. BDNF serum levels and metabolic parameters: fasting serum glucose, cholesterol, triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C) were measured at baseline and week 8 of treatment.

Results: There were no differences between BDNF level in depressed patients compared with the healthy controls. Lack of differences in medication effect of sertraline or venlafaxine on HDRS-17 scores during 8 weeks of treatment was observed. Correlation of BDNF at baseline and fasting serum glucose at baseline and week 8 was detected.

Conclusions: Correlations of BDNF serum levels with metabolic parameters were observed.     

Effects of antidepressant treatment on mice lacking brain‐derived neurotrophic factor expression through promoter IV

Brain‐derived neurotrophic factor (BDNF) is implicated in the pathophysiology of major depression; mice lacking BDNF expression through promoter IV (BDNF‐KIV) exhibit a depression‐like phenotype. We tested our hypothesis that deficits caused by promoter IV deficiency (depression‐like behavior, decreased levels of BDNF, and neurogenesis in the hippocampus) could be rescued by a 3‐week treatment with different types of antidepressants: fluoxetine, phenelzine, duloxetine, or imipramine. Each antidepressant reduced immobility time in the tail suspension test without affecting locomotor activity in the open field test in both BDNF‐KIV and control wild type mice, except that phenelzine increased locomotor activity in wild type mice and anxiety‐like behavior in BDNF‐KIV mice. The antidepressant treatments were insufficient to reverse decreased BDNF levels caused by promoter IV deficiency. No antidepressant treatment increased the hippocampal progenitors of either genotype, whereas phenelzine decreased the surviving progenitors in both genotypes. The antidepressant treatments differently affected the dendritic extension of hippocampal immature neurons: fluoxetine and imipramine increased extension in both genotypes, duloxetine increased it only in BDNF‐KIV mice, and phenelzine decreased it only in wild type mice. Interestingly, a saline‐only injection increased neurogenesis and dendrite extensions in both genotypes. Our results indicate that the behavioral effects in the tail suspension test by antidepressants do not require promoter IV‐driven BDNF expression and occur without a detectable increase in hippocampal BDNF levels and neurogenesis but may involve increased dendritic reorganisation of immature neurons. In conclusion, the antidepressant treatment demonstrated limited efficacy; it partially reversed the defective phenotypes caused by promoter IV deficiency but not hippocampal BDNF levels.     

The roles of BDNF in the pathophysiology of major depression and in antidepressant treatment

Neurotrophic factors are critical regulators of the formation and plasticity of neuronal networks. Brain-derived neurotrophic factor (BDNF) is abundant in the brain and periphery, and is found in both human serum and plasma. Animal studies have demonstrated that stress reduces BDNF expression or activity in the hippocampus and that this reduction can be prevented by treatment with antidepressant drugs. A similar change in BDNF activity occurs in the brain of patients with major depression disorder (MDD). Recently, clinical studies have indicated that serum or plasma BDNF levels are decreased in untreated MDD patients. Antidepressant treatment for at least four weeks can restore the decreased BDNF function up to the normal value. Therefore, MDD is associated with impaired neuronal plasticity. Suicidal behavior can be a consequence of severe impaired neuronal plasticity in the brain. Antidepressant treatment promotes increased BDNF activity as well as several forms of neuronal plasticity, including neurogenesis, synaptogenesis and neuronal maturation. BDNF could also play an important role in the modulation of neuronal networks. Such a neuronal plastic change can positively influence mood or recover depressed mood. These alterations of BDNF levels or neuronal plasticity in MDD patients before and after antidepressant treatment can be measured through the examination of serum or plasma BDNF concentrations. BDNF levels can therefore be useful markers for clinical response or improvement of depressive symptoms, but they are not diagnostic markers of major depression.     

Serum brain-derived neurotrophic factor levels in patients with major depression: effects of antidepressants

This study tried to investigate the relationships between serum brain-derived neurotrophic factor (BDNF) protein levels and major depressive patients and discuss the effects of antidepressants on the serum BDNF protein levels. A total of 218 participants, including 111 patients with major depression (91 women) and 107 healthy controls (65 women), were recruited in this study. Serum BDNF protein levels were measured using an ELISA kit. Psychiatric diagnoses were made according to DSM-IV criteria. Severity of major depression was assessed by the 17-item Hamilton Depression Rating Scale. Using analysis of covariance with age adjustment, there were significantly low serum BDNF protein levels in depressive patients than healthy controls in women (F=7.530, p=0.007), but not in men. Additionally, changes in serum BDNF protein levels were significantly increased in 79 patients taking antidepressants during a period of 4 weeks (t=2.116, p=0.038), especially in 61 women (t=2.542, p=0.014). Age-adjusted ANCOVA revealed no significant differences in serum BDNF protein levels between 58 responders and 21 non-responders (F=0.008, P=0.928). In responders, there were significantly increased changes in serum BDNF protein levels in 44 women (t=2.501, p=0.016), but not in 14 men (t=-0.767, p=0.457). These analytical results suggest that low serum BDNF may play an important role in depressive women and antidepressant treatment significantly increase serum BDNF. However, further studies of larger populations are necessary to confirm these results and further elucidate the effects of different classes of antidepressants on serum BDNF protein levels.     

文拉法辛对慢性应激抑郁大鼠前额区可塑性相关蛋白mRNA表达的影响

目的：探讨文拉法辛对慢性应激抑郁大鼠前额区3种可塑性相关蛋白mRNA表达的影响。方法：用慢性不可预见应激（CUS）方法建立抑郁大鼠模型，给予2种剂量（5mg／kg和10mg／kg）的抗抑郁药物文拉法辛14d或28d，用逆转录-聚合酶链反应检测大鼠前额区脑源性神经营养因子（BDNF）、转录因子环磷腺苷反应元件结合蛋白（CREB）和神经细胞粘附分子（NCAM）mRNA表达的变化。结果：抑郁模型大鼠体质量增加量，蔗糖水消耗量和行为学测试均较正常组明显下降，提示抑郁模型大鼠在第28天建立成功。CUS28d后前额区BDNF、CREB和NCAM mRNA表达均较正常组明显降低（P〈0．05），5mg／kg文拉法辛组明显增加抑郁模型大鼠前额区3种可塑性相关蛋白mRNA的表达，10mg／kg文拉法辛组轻度降低抑郁模型大鼠前额区3种可塑性相关蛋白mRNA的表达。结论：文拉法辛在调节前额区神经可塑性时具有剂量依赖性，BDNF、CREB和NCAM在抑郁症病因和治疗中可能发挥着重要作用。     

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.     

Serum concentrations of nerve growth factor and brain-derived neurotrophic factor in depressed patients before and after antidepressant treatment

INTRODUCTION: Stress, glucocorticoids and anti-depressant treatment have been found to modulate the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Recent research suggests that serum BDNF concentration is reduced in depression and that successful antidepressant treatment leads to an increase in serum BDNF concentration. METHODS: We studied depressed patients receiving a standardized antidepressant treatment with either 150 mg amitriptyline (n=20) or 40 mg paroxetine (n=20) for 36 days in a prospective design. Changes in the concentrations of serum neurotrophins and salivary cortisol in response to antidepressant treatment were assessed. RESULTS: Independent of clinical efficacy there was a significant 'treatment' by 'medication' interaction effect on BDNF serum concentrations that indicated a decline of BDNF by 12% in paroxetine-treated patients while there was an increase by 13% in amitriptyline-treated patients. Neither antidepressant altered NGF concentrations. The changes in cortisol and neurotrophin concentrations were not related. DISCUSSION: Changes in BDNF serum concentrations as a result of antidepressant therapy depend on the antidepressant instead of being a general characteristic of response to antidepressant treatment.     

Brain-derived neurotrophic factor and subcallosal deep brain stimulation for refractory depression

Objectives. Subcallosal cingulate (SCC) deep brain stimulation (DBS) is a promising experimental treatment for treatment-resistant depression (TRD). Given the role of brain-derived neurotrophic factor (BDNF) in neuroplasticity and antidepressant efficacy, we examined the effect of SCC-DBS on serum BDNF in TRD. Methods. Four patients with TRD underwent SCC-DBS treatment. Following a double-blind stimulus optimization phase of 3 months, patients received continuous stimulation in an open label fashion for 6 months. Clinical improvement in depressive symptoms was evaluated bi-weekly for 6 months using the Hamilton Depression Rating Scale (HDRS). Mature serum BDNF levels were measured before and 9–12 months after surgery. Results. Three patients responded to SCC-DBS: two showed full clinical response (50% reduction in HDRS scores) and one had partial response (35% reduction in HDRS scores) at the clinical endpoint. Interestingly, all four patients showed reduction in serum BDNF concentration from pre-DBS baseline. Conclusions. SCC-DBS for TRD may be associated with decreased levels of serum BDNF. Longitudinal studies with multiple measurements in a larger sample are required to determine the role of BDNF as a biomarker of SCC-DBS antidepressant efficacy.     

Chronic restraint stress causes anxiety- and depression-like behaviors, downregulates glucocorticoid receptor expression, and attenuates glutamate release induced by brain-derived neurotrophic factor in the prefrontal cortex

Stress and the resulting increase in glucocorticoid levels have been implicated in the pathophysiology of depressive disorders. We investigated the effects of chronic restraint stress (CRS: 6hours×28days) on anxiety- and depression-like behaviors in rats and on the possible changes in glucocorticoid receptor (GR) expression as well as brain-derived neurotrophic factor (BDNF)-dependent neural function in the prefrontal cortex (PFC). We observed significant reductions in body weight gain, food intake and sucrose preference from 1week after the onset of CRS. In the 5th week of CRS, we conducted open-field (OFT), elevated plus-maze (EPM) and forced swim tests (FST). We observed a decrease in the number of entries into open arms during the EPM (anxiety-like behavior) and increased immobility during the FST (depression-like behavior). When the PFC was removed after CRS and subject to western blot analysis, the GR expression reduced compared with control, while the levels of BDNF and its receptors remained unchanged. Basal glutamate concentrations in PFC acute slice which were measured by high performance liquid chromatography were not influenced by CRS. However, BDNF-induced glutamate release was attenuated after CRS. These results suggest that reduced GR expression and altered BDNF function may be involved in chronic stress-induced anxiety- and depression-like behaviors.     

Antidepressant-like behavioral, neurochemical and neuroendocrine effects of naringenin in the mouse repeated tail suspension test

Our previous study demonstrated that the citrus bioflavonoid naringenin ameliorated behavioral alterations via the central serotonergic and noradrenergic systems in the tail suspension test (TST) induced mice. To better understand its pharmacological activity, mice were submitted to three 6min-TSTs one week apart (Day 1: test, Day 7: retest 1, Day 14: retest 2) followed by hippocampal glucocorticoid receptor (GR), monoamine neurotransmitters and serum corticosterone measurement. The results suggested that repeated TST detected the gradual increase in the efficacy of naringenin over time, additionally 1-day (20mg/kg), 7-day (10, 20mg/kg) and 14-day (5, 10, 20mg/kg) naringenin treatment markedly decreased the immobility time. Moreover, administration of naringenin for 14days (20mg/kg) increased hippocampal serotonin (5-HT), norepinephrine (NE) and GR levels, and reduced serum corticosterone levels in mice exposed to the repeated TST. Overall, the present study indicated that the re-exposure would facilitate the detection of the anti-immobility effects of antidepressant drugs in the mouse TST, and clearly demonstrated that the antidepressant-like effect of naringenin may be mediated by an interaction with neuroendocrine and neurochemical systems.     

Characterization and functional significance of glucocorticoid receptors in patients with major depression: modulation by antidepressant treatment

Hyperactivity of the hypothalamic pituitary adrenal (HPA) axis in patients with major depression is one of the most consistent findings in biological psychiatry. Experimental data support the idea that glucocorticoid-mediated feedback via glucocorticoid receptors (GR) is impaired in major depression. The aim of the present work was to assess the putative changes in GR density of peripheral blood mononuclear cells (PBMCs) in a group of patients with major depression and to determine modulation of these GR sites by antidepressant treatment. In addition, susceptibility of PBMCs to glucocorticoid effects was also studied using a functional end-point analysis in vitro, such as cortisol inhibition of mitogen-induced lymphocyte proliferation. Cortisol levels were also measured before and after dexamethasone suppression test (DST). The results showed a decrease in GR density in depressed patients compared with healthy subjects, mainly in those patients that showed basal cortisol levels in the upper normal range and were refractory to DST. Regarding the functional significance of this variation, two representative groups emerged from our study: a) free-medication patients with GR function comparable to healthy controls, and b) patients showing diminished GR activity. These results suggest a lack of relationship between GR density and cortisol-induced inhibition of lymphocyte proliferation. Patients treated with different antidepressant drugs showed a marked increase in the number of GR sites per cell compared to non-treated. Interestingly, this increase was even higher than in normal subjects. Hence, restoration of GR density after an efficient antidepressant treatment could be an index of an effective modulatory action of drugs on GR expression and highlights the possibility that GR levels might be used as markers of a successful treatment.