GSK650394对慢性应激抑郁症模型大鼠行为及海马神经营养的调节作用

目的探讨血清和糖皮质激素调节蛋白激酶1(SGK1)抑制剂GSK650394对抑郁症模型大鼠抑郁样行为及海马神经营养的调节作用。方法将SD大鼠随机分为对照组、抑郁模型(慢性温和不可预见性应激加孤养)组、GSK650394(2.8 g/L,按1 mL/kg腹腔注射)干预组;采用强迫游泳、糖水消耗、Morris水迷宫实验观察模型动物的情绪行为变化;用ELISA检测大鼠海马血浆和血清中皮质酮(CORT)、5-羟色胺(5-HT)、去甲肾上腺素(NE)含量;用Western blot检测海马中脑源性神经营养因子(BDNF)、神经营养素3(NT-3)、神经生长因子(NGF)的表达。结果与对照组比较,模型组大鼠蔗糖水偏食度显著降低、游泳不动时间增加(P<0.01)、逃避潜伏期(EL)、目标象限的潜伏时间(Lat.T)均显著延长(P<0.05或P<0.01);血浆CORT显著升高(P<0.01)、血清5-HT、NE和海马NT-3、BDNF、NGF表达显著降低(P<0.05或P<0.01)。与模型组比较,GSK650394可显著增加蔗糖水偏食度、降低游泳不动时间(P&l...     

慢性皮质酮注射对小鼠抑郁样行为及脑糖原水平的影响

目的:探讨慢性皮质酮注射对小鼠抑郁样行为以及脑糖原水平的影响。方法:将40只雄性C57BL/6N小鼠随机分为正常对照组与模型组,模型组小鼠连续4周给予皮质酮皮下注射,构建慢性应激抑郁障碍小鼠模型。采用强迫游泳实验和旷场实验验证慢性应激模型的建立;放免法测定小鼠血清中皮质酮(CORT)水平;采用蛋白免疫印迹法检测海马突触素(SYP)和脑源性神经营养因子(BDNF)的蛋白表达水平;采用荧光间接测定法检测海马组织的糖原以及糖原合酶和糖原磷酸化酶的水平。结果:与正常对照组相比,模型组强迫游泳静止不动时间延长(P0.01)、自主活动能力降低(P0.01),表明慢性皮质酮注射诱导小鼠产生抑郁样行为。抑郁小鼠的皮质酮明显升高(P0.01)。皮质酮注射降低海马SYP和BDNF的蛋白表达(P0.01),同时海马组织糖原含量减少(P0.05),糖原合酶的活性降低(P0.05),而糖原磷酸化酶活性增加(P0.05)。结论:慢性皮质酮注射引起的海马神经元损伤和诱导小鼠抑郁样行为,可能与皮质酮降低海马糖原水平有关。     

Fluoxetine treatment induces dose dependent alterations in depression associated behavior and neural plasticity in female mice

Antidepressant-induced increases in neurogenesis and neurotrophin mobilization in rodents and primates are proposed to be necessary for behavioral efficacy. The current study examines the relationship between the effects of fluoxetine treatment on behavior, cell proliferation and the neurotrophin BDNF in females. Female MRL/MpJ mice were treated acutely (5 and 10 mg/kg) or chronically (2.5, 5 and 10 mg/kg b.i.d.) with fluoxetine and tested in the tail suspension test (TST) and or novelty-induced hypophagia test (NIH), respectively. Mice treated chronically with fluoxetine received 4 (100 mg/kg) injections of 5-bromo-2′-deoxyuridine (BrdU) on the last 4 days of treatment to measure DNA synthesis. The other half of the hippocampus and the frontal cortex was removed and examined for BDNF levels. Fluoxetine treatment decreased immobility in the TST and latency to eat in the NIH test, but only the highest dose of fluoxetine significantly altered behavior in both tests. Chronic treatment with 5 and 10 mg/kg of fluoxetine significantly increased cell proliferation and BDNF levels in the hippocampus. Only chronic treatment with the highest of fluoxetine increased BDNF levels in the frontal cortex. Behavioral measures in the NIH test correlated with BDNF levels in the frontal cortex but not in the hippocampus or with cell proliferation in the hippocampus. These data suggest that females require high doses of fluoxetine for behavioral efficacy regardless of elevations of neurogenesis and BDNF mobilization in the hippocampus. Elevations in BDNF levels in the frontal cortex are related to the behavioral efficacy of fluoxetine.     

小鼠慢性酒精中毒及戒断过程中抑郁样行为的改变及其共病机制

 目的: 研究小鼠慢性酒精中毒及戒断过程中抑郁样行为的改变,进一步探讨酒精中毒与抑郁症的共病机制。方法: 构建新型慢性酒精中毒小鼠模型;实验分为正常对照组及慢性酒精7 d、14 d、21 d和28 d组。在第6、13、20和27天分别进行酒精偏好度测试,测试后戒断酒精1 d,随后次日进行抑郁行为学测试,测试结束后处死小鼠取海马与额叶皮层,采用高效液相色谱法测定5-羟色胺(5-HT)及去甲肾上腺素(NE)含量,采用免疫印迹法测定cAMP反应元件结合蛋白(CREB)和脑源性神经营养因子(BDNF)的含量。结果: 随着酒精饮酒天数及戒断次数的增加,小鼠表现出明显嗜酒现象,并且在强迫游泳和悬尾测试中,表现出明显的不动时间增加。7 d组小鼠额叶皮层内5-HT水平升高(P < 0.05),海马与额叶5-HT水平在21 d与28 d组降低(P < 0.01);7 d和14 d组小鼠海马与额叶NE水平无明显变化,21 d和28 d组NE水平降低(P < 0.05)。21 d和28 d组小鼠海马与额叶内p-CREB/CREB比值及BDNF表达水平明显下降(P < 0.05),7 d与14 d组无明显变化。结论: 酒精中毒、戒断阶段与抑郁的共病机制涉及5-HT。5-HT-cAMP-CREB-BDNF信号转导通路可能为酒精中毒与抑郁症的共病机制。     

磷酸二酯酶4抑制剂咯利普兰逆转慢性酒精中毒及戒断诱导的小鼠抑郁样行为

目的:研究磷酸二酯酶4(PDE4)抑制剂咯利普兰对酒精中毒戒断诱导的抑郁样行为的作用及对小鼠海马和前额叶皮质脑区环磷酸腺苷(cAMP)、蛋白激酶A(PKA)、cAMP反应元件结合蛋白(CREB)、磷酸化CREB(p-CREB)和脑源性神经营养因子(BDNF)表达的影响。方法:取60只雄性ICR小鼠,随机分为空白对照组、空白+咯利普兰组、慢性酒精模型组和咯利普兰治疗组(0.1、0.5和1 mg/kg)。给予酒精28 d期间每周进行酒精戒断处理。慢性酒精处理后,进行强迫游泳测试(FST)和悬尾测试(TST),观察小鼠抑郁样行为;ELISA检测小鼠海马和前额叶皮质cAMP含量,Western blot检测小鼠海马和额叶皮质PKA、CREB、p-CREB和BDNF的表达。结果:随着饮酒天数及戒断次数的增加,小鼠表现出明显嗜酒现象,饮酒量增加(P0.01),FST和TST测试中的不动时间增加(P0.01)。小鼠给药咯利普兰(0.5和1 mg/kg)28 d后,FST和TST不动时间与模型组相比明显减少(P0.05),且能改善小鼠的嗜酒现象,小鼠饮酒量与模型组相比明显减少(P0.01);相比于正常组,模型组小鼠海马和前额叶皮质cAMP含量明显降低(P0.01),并且海马和额叶皮质PKA、p-CREB和BDNF也明显低于正常水平(P0.01)。咯利普兰(0.5和1 mg/kg)给药28 d后,海马与前额叶皮质cAMP含量明显增加(P0.01),酒精抑制的海马脑区PKA、p-CREB和BDNF表达被逆转(P0.05),且酒精抑制的前额叶皮质PKA和p-CREB表达被逆转(P0.05)。结论:磷酸二酯酶4抑制剂咯利普兰能明显改善酒精中毒及戒断引起的抑郁样症状,且能减轻嗜酒症状,机制可能涉及第二信使cAMP通路。咯利普兰通过抑制PDE4,增加海马与前额叶皮质cAMP水平,进而激活PKA-CREB-BDNF通路,从而产生抗抑郁作用。     

Differential brain,but not serum VEGF levels in a genetic rat model of depression

Compared to the classical monoamine hypotheses focus on neuroplasticity is a major new approach in studies of depression and antidepressants. Recent studies have demonstrated that vascular endothelial growth factor (VEGF) is regulated by antidepressant treatment in rodents. However, in depressive patients no significant changes were found in the serum VEGF levels compared to control subjects. To our knowledge, brain and serum VEGF levels have never been reported in parallel for any psychiatric disease model. That prompted us to examine the levels of VEGF in serum, hippocampus, frontal cortex, corpus striatum, and hypothalamus in male Flinders Sensitive Line (FSL) and Flinders Resistant Line (FRL), a genetic rat model of depression. The VEGF levels were identical in the FSL and the FRL rats in serum, corpus striatum, and hypothalamus. In hippocampus and frontal cortex, the VEGF levels were significantly decreased in the FSL rats compared to the FRL rats. The results may add to the hypothesis that altered expression of growth factors/neurotrophic factors are related to the pathophysiology of depression.     

Inhibitory effects of valproate on impairment of Y-maze alternation behavior induced by repeated electroconvulsive seizures and c-Fos protein levels in rat brains

We previously showed that inhibition of repeated electroconvulsive shock (ECS)-induced seizures through 7-day administration of anti-epileptic drugs suppressed the impairment of spontaneous alternation behavior in the Y-maze test in rats. To clarify the precise mechanism(s), we investigated the effect of valproate on such impairment and examined the levels of brain-derived neurotrophic factor (BDNF) and c-Fos protein in the prefrontal cortex and the hippocampus 24h after the last administration of ECS. Seven-day intraperitoneal (i.p.) administration of valproate (400mg/kg) suppressed the impairment of spontaneous alternation behavior. Repeated ECS increased the BDNF protein levels in the hippocampus and prefrontal cortex in the presence or absence of valproate, indicating that the increase in BDNF protein levels resulted from electrical stimulation. c-Fos protein levels were significantly decreased in the hippocampal dentate gyrus after repeated ECS, but valproate had no significant effect on decreased c-Fos protein levels. Valproate＋ECS significantly increased the c-Fos protein levels of the prefrontal cortex compared with the ECS group. These findings suggest that the inhibitory effect of valproate on repeated ECS-induced impairment of spontaneous alternation behavior may be linked to the prefrontal cortex.     

Chronic corticosterone administration down-regulates metabotropic glutamate receptor 5 protein expression in the rat hippocampus

Several lines of evidence suggest a dysfunctional glutamate system in major depressive disorder (MDD). Recently, we reported reduced levels of metabotropic glutamate receptor subtype 5 (mGluR5) in postmortem brains in MDD, however the neurobiological mechanisms that induce these abnormalities are unclear. In the present study, we examined the effect of chronic corticosterone (CORT) administration on the expression of mGluR5 protein and mRNA in the rat frontal cortex and hippocampus. Rats were injected with CORT (40 mg/kg s.c.) or vehicled once daily for 21 days. The expression of mGluR5 protein and mRNA was assessed by Western blotting and quantitative real-time PCR (qPCR). In addition, mGluR1 protein was measured in the same animals. The results revealed that while there was a significant reduction (−27%, P=0.0006) in mGluR5 protein expression in the hippocampus from CORT treated rats, mRNA levels were unchanged. Also unchanged were mGluR5 mRNA and protein levels in the frontal cortex and mGluR1 protein levels in both brain regions. Our findings provide the first evidence that chronic CORT exposure regulates the expression of mGluR5 and are in line with previous postmortem and imaging studies showing reduced mGluR5 in MDD. Our findings suggest that elevated levels of glucocorticoids may contribute to impairments in glutamate neurotransmission in MDD.     

毛蕊花糖苷通过调控BDNF-TrkB信号通路改善CUMS大鼠的抑郁样行为

目的:观察毛蕊花糖苷(acteoside)对慢性不可预见性温和应激(chronic unpredictable mild stress,CUMS)大鼠抑郁样行为的影响,并探讨脑源性神经营养因子-原肌球蛋白受体激酶B(brain-derived neurotrophic factor-tropomyosin receptor kinase B,BDNF-TrkB)信号通路在其中的作用机制。方法:采用CUMS结合孤养的方式制备抑郁模型大鼠,成模后随机分为模型组、盐酸氟西汀(20 mg/kg)组和毛蕊花糖苷(30 mg/kg、60 mg/kg和120 mg/kg)组,每组18只,另取18只正常大鼠作为对照组,连续灌胃给药3周。采用强迫游泳实验和糖水偏好实验检测大鼠抑郁样行为的变化;免疫荧光和Western blot法检测大鼠海马BDNF-TrkB信号通路相关蛋白的表达情况;ELISA法检测脑组织中单胺类神经递质5-羟色胺(5-HT)、多巴胺(DA)和去甲肾上腺素(NE)的含量。结果:与对照组比较,模型组大鼠强迫游泳不动时间明显延长,糖水偏好量明显下降,海马BDNF和TrkB的表达均明显降低,脑组织中5-HT、DA和NE含量均显著减少;与模型组比较,盐酸氟西汀组和毛蕊花糖苷各剂量组以上各检测指标均得到显著逆转(P0.05)。结论:毛蕊花糖苷可能通过上调海马BDNF-TrkB信号通路、增加脑内单胺类神经递质含量而改善CUMS大鼠的抑郁样行为。     

Chronic corticosterone administration from adolescence through early adulthood attenuates depression-like behaviors in mice

There is evidence that depression may have a different neural basis at different ages. Although chronic stress and elevated glucocorticoid levels have been demonstrated to lead to the emergence of mood disorders, it remains unclear how moderate elevation of glucocorticoid levels in young animals influences depression-like behaviors and brain functions. To address this issue, the present study examines how chronic corticosterone (CORT) administration during adolescence and early adulthood influences depression-like behaviors, hypothalamic-pituitary-adrenal (HPA) axis response and hippocampal cell proliferation. Male mice were chronically administrated with CORT drinking water (20mg/L) during adolescence. After two months of treatment, serum CORT levels were measured using enzyme immunoassay. Hippocampal glucocorticoid and mineralocorticoid receptors were characterized using Western blot. Tail suspension and forced swim tests were used to assess depression-related behaviors in mice. Immunohistochemistry was performed to measure bromodeoxyuridine (BrdU) incorporation in order to assess cell proliferation in the hippocampus. Our results suggest that chronic CORT administration induced a mild but not significant elevation in basal CORT levels and attenuated the physiological responses to stress. Chronic CORT administration also reduced expression of the hippocampal mineralocorticoid receptor and decreased immobility time in both the tail suspension test and the forced swim test. Moreover, chronic CORT administration increased the BrdU immunoreactivities in the hippocampus. Taken together, these findings suggest that chronic mild elevation by CORT administration during the adolescence and early adulthood attenuates depression-like behaviors.     

Voluntary exercise protects against stress-induced decreases in brain-derived neurotrophic factor protein expression

Exercise is increasingly recognized as an intervention that can reduce CNS dysfunctions such as cognitive decline, depression and stress. Previously we have demonstrated that brain-derived neurotrophic factor (BDNF) is increased in the hippocampus following exercise. In this study we tested the hypothesis that exercise can counteract a reduction in hippocampal BDNF protein caused by acute immobilization stress. Since BDNF expression is suppressed by corticosterone (CORT), circulating CORT levels were also monitored. In animals subjected to 2 h immobilization stress, CORT was elevated immediately following, and at 1 h after the cessation of stress, but remained unchanged from baseline up to 24 h post-stress. The stress protocol resulted in a reduction in BDNF protein at 5 and 10 h post-stress that returned to baseline at 24 h. To determine if exercise could prevent this stress-induced reduction in BDNF protein, animals were given voluntary access to running wheels for 3 weeks prior to the stress. Stressed animals, in the absence of exercise, again demonstrated an initial elevation in CORT (at 0 h) and a subsequent decrease in hippocampal BDNF at the 10 h time point. Exercising animals, both non-stressed and stressed, demonstrated circulating CORT and hippocampal BDNF protein levels that were significantly elevated above control values at both time points examined (0 and 10 h post-stress). Thus, the persistently high CORT levels in exercised animals did not affect the induction of BDNF with exercise, and the effect of immobilization stress on BDNF protein was overcome. To examine the role of CORT in the stress-related regulation of BDNF protein, experiments were carried out in adrenalectomized (ADX) animals. BDNF protein was not downregulated as a result of immobilization stress in ADX animals, while there continued to be an exercise-induced upregulation of BDNF. This study demonstrates that CORT modulates stress-related alterations in BDNF protein. Further, exercise can override the negative effects of stress and high levels of CORT on BDNF protein. Voluntary physical activity may, therefore, represent a simple non-pharmacological tool for the maintenance of neurotrophin levels in the brain.     

慢性应激对心肌梗死后大鼠模型行为学及海马BDNF的影响

目的:探讨慢性应激对心肌梗死后大鼠模型行为学及海马BDNF的影响.方法:建立急性心肌梗死模型.结合慢性不可预见的轻度应激和孤养制作心梗并抑郁复合大鼠模型.观察动物的体重变化和行为学指标,用Westernblot方法检测海马BDNF蛋白表达.结果:经过21天慢性不可预见轻度应激.模型组大鼠体重、糖水消耗和糖水偏爱百分比、敞箱试验得分均明显降低,纯水消耗显著增加;海马BDNF蛋白表达减少(P<0.05).结论:对急性心肌梗死大鼠采用21天慢性应激后,模型鼠体重下降、行为学明显异常,符合抑郁动物的行为学改变,且存在海马神经元可塑性降低的表现,这可能是心肌梗死并抑郁发病的机制之一.     

Corticosterone increases depression-like behavior, with some effects on predator odor-induced defensive behavior, in male and female rats

This experiment examined the effect of repeated corticosterone injections on anxiety and depression-like behavior in male and female rats. Rats received either corticosterone or vehicle injections for 21 consecutive days prior to behavioral testing in the forced swim, open-field, and predator odor tests. The corticosterone injections significantly increased depression-like behavior in the forced swim test in both male and female rats but had no significant effect on anxiety in the open-field test. In the predator odor test, the corticosterone injections significantly increased a subset of defensive behaviors in the male rats. These results suggest that repeated exposure to corticosterone increases depression-like behavior, with some effects on anxiety, and that male rats may be more affected than female rats by this manipulation.     

白松片对慢性应激抑郁模型大鼠行为学及血浆CORT、ACTH的影响

目的：观察白松片对慢性应激抑郁大鼠模型行为学和血浆CORT、ACTH含量的影响。方法：SD雄性大鼠28只随机分为空白对照组、模型对照组、氟西汀对照组及白松片试验组，选用慢性轻度不可预见性应激加孤养造模，观察各组大鼠敞箱实验和液体消耗等行为学指标变化，采用放射免疫方法检测大鼠血浆皮质醇(CORT)和促肾上腺皮质激素(ACTH)含量。结果：慢性应激抑郁大鼠体重增加缓慢，敞箱实验中的水平运动、垂直运动得分、清洁动作次数显著减少，中央格停留时间显著延长；糖水消耗明显下降，纯水消耗显著增多，而且其血浆皮质醇和促肾上腺皮质激素含量增加。氟西汀和白松片均显著改善慢性应激抑郁大鼠模型的行为学和神经内分泌变化。结论：慢性轻度不可预见性应激可使大鼠行为及神经内分泌发生异常改变，引起抑郁状态，白松片对此具有一定拮抗作用。     

Chronic high corticosterone reduces neurogenesis in the dentate gyrus of adult male and female rats

Adult neurogenesis in the dentate gyrus of the hippocampus is altered with stress exposure and has been implicated in depression. High levels of corticosterone (CORT) suppress neurogenesis in the dentate gyrus of male rats. However both acute and chronic stress do not consistently reduce adult hippocampal neurogenesis in female rats. Therefore, this study was conducted to investigate the effect of different doses of corticosterone on hippocampal neurogenesis in male and female rats. Rats received 21 days of s.c. injections of either oil, 10 or 40 mg/kg CORT. Subjects were perfused 24 h after the last CORT injection and brains were analyzed for cell proliferation (Ki67-labeling) or immature neurons (doublecortin-labeling). Results show that in both males and females high CORT, but not low CORT, reduced both cell proliferation and the density of immature neurons in the dentate gyrus. Furthermore, high CORT males had reduced density in immature neurons in both the ventral and dorsal regions while high CORT females only showed the reduced density of immature neurons in the ventral hippocampus. The high dose of CORT disrupted the estrous cycle of females. Further, the low dose of CORT significantly reduced weight gain and increased basal CORT levels in males but not females, suggesting a greater vulnerability in males with the lower dose of CORT. Thus we find subtle sex differences in the response to chronic CORT on both body weight and on neurogenesis in the dorsal dentate gyrus that may play a role in understanding different vulnerabilities to stress-related neuropsychiatric disorders between the sexes.     

Effect of Imipramine and Prolyl Endopeptidase Inhibitor Benzyloxycarbonyl-Methionyl-2(S)-Cyanopyrrolidine on Activity of Proline-Specific Peptidases in the Brain of Rats with Experimental Anxious-Depressive Syndrome

Activities of prolyl endopeptidase and dipeptidyl peptidase IV in the frontal cortex, hypothalamus, nucleus accumbens, striatum, and hippocampus were measured in rats with the experimental anxious-depressive syndrome induced by treatment with a dipeptidyl peptidase IV inhibitor during the early postnatal period (days 5-18). Prolyl endopeptidase activity was elevated in the frontal cortex, hypothalamus, and nucleus accumbens. Increased activity of dipeptidyl peptidase IV was observed in the hypothalamus and striatum. Norepinephrine/serotonin reuptake inhibitor, imipramine, and noncompetitive prolyl endopeptidase inhibitor, benzyloxycarbonyl-methionyl-2(S)-cyanopyrrolidine, were shown to abolish depression-like behavior of animals in the forced swimming test. These compounds had a normalizing effect on activities of prolyl endopeptidase and dipeptidyl peptidase IV in brain structures of rats.     

Comparative study of neuroprotective effect of tricyclics vs. trazodone on animal model of depressive disorder

The neurobiological model of depressive disorder may be correlated with the animal model on rat, hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, the increase of cortisol level being specific to the model of depression in women. The neurobiological model of depression in women presents vulnerabilities for some cerebral structures (hippocampus, frontal cortex, cerebral amygdala). A decrease of frontal cortex and hippocampus volumes are recognized in depressive disorder in women, depending on duration of disease and antidepressant therapy. Neurobiological vulnerability may be pronounced through cholinergic blockade. The purpose of the study was to highlight the cytoarchitectural changes in the frontal cortex and hippocampus by comparing two antidepressant substances: amitriptyline with a strong anticholinergic effect and trazodone, without anticholinergic effect. The superior neuroprotective qualities of trazodone for the frontal cortex, hippocampus and dentate gyrus are revealed. The particular neurobiological vulnerability of depression in women requires a differentiated therapeutic approach, avoiding the use of antidepressants with anticholinergic action.     

Involvement of neurotrophic factors in aging of noradrenergic innervations in hippocampus and frontal cortex

In the present study, we investigated the age-dependent changes in the axon terminals of the locus coeruleus (LC) neurons in the frontal cortex and hippocampus, in which a high degree of axonal branching in the middle-aged brain was suggested to occur in our previous electrophysiological study. We used 6-, 13- and 25-month-old male F344/N rats, and performed Western blot analysis of the norepinephrine transporter (NET), brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF). NET expression level increased in the 13-month-old hippocampus, but was not altered by aging in the frontal cortex. BDNF expression level increased in the hippocampus, but did not change with age in the frontal cortex. On the other hand, GDNF expression level was increased with age in the frontal cortex, but was not in the hippocampus. These results suggest that the LC noradrenergic innervations may be locally regulated by different neurotrophic factors that exert their trophic actions at different target sites.