抑郁症大鼠海马5-羟色胺含量及中缝核色氨酸羟化酶-2表达变化的研究

目的 观察抑郁症模型大鼠海马5-羟色胺(5-HT)含量及其合成限速酶--色氨酸羟化酶-2(TPH2)表达的变化.方法 雌性Sprngue-Dawley大鼠20只,随机分为正常组和模型组;模型组给予孤养加21 d慢性不可预见性温和应激(以下简称应激).采用旷场试验测试大鼠的行为学变化;高效液相色谱-电化学法测定大鼠海马5-HT的含量;逆转录聚合酶链反应技术检测中缝核TPH2mBNA的表达量;荧光免疫组化检测中缝核TPH2蛋白的表达.结果 应激第21天,模型组大鼠直立活动[(0.43±1.13)分]及水平活动得分[(5.86±8.26)分]均低于正常组[分别为(1.75±2.44)分和(13.75±19.02)分],P<0.05;海马5-HT含量[(2340±426)ng/s组织]明显低于正常组[(3569±652)ng/g组织],P<0.01;中缝核TPH2 mRNA相对表达量(0.89±0.15)低于正常组(1.12±0.19).P<0.05;中缝核TPH2阳性细胞数[(75±29)个]低于正常组[(171±113)个],P<0.05.结论 孤养加21 d应激可造成大鼠抑郁症模型;模型组大鼠海马5-HT含量下降,可能是由于中缝核TPH2的表达减少,使5-HT合成减少所致.     

慢性应激抑郁大鼠脑内5-羟色胺受体mRNA表达

目的探讨慢性应激抑郁模型大鼠脑内前额叶、海马、中缝核、伏隔核5—羟色胺1A(5—HT1A)与5—羟色胺2A(5—HT2A)受体m RNA表达的变化。方法将成年雄性SD大鼠适应性喂养1w后随机分为实验组和对照组,每组10只。实验组连续28d,随机给予强迫游泳、夹尾、潮湿垫料、鼠笼倾斜、食物和水的剥夺等其中一种刺激,建立慢性轻度不可预知应激动物模型。对照组正常饲养,不予以实验性处理。采用旷场实验及糖水偏好实验评定其行为学改变;应用逆转录聚合酶链反应检测并比较两组大鼠大脑中前额叶、海马、中缝核、伏隔核5—HT1A与5—HT2A受体m RNA的表达水平。结果 1实验组5—HTl A受体m RNA表达在前额叶、海马、中缝核、伏隔核中分别为1.35±0.05、1.76±0.35、0.84±0.67、2.17±0.56,对照组分别为1.57±0.38、2.04±0.71、0.92±0.12、2.25±0.09。2组比较差异无统计学意义(P0.05);2实验组5—HT2A受体m RNA表达在前额叶、海马、中缝核、伏隔核中分别为1.24±0.80、0.37±0.75、0.34±0.14、0.45±0.41,对照组分别为1.66±0.43、2.02±0.12、1.90±0.56、1.28±0.31,2组比较在海马,中缝核,伏隔核中差异有统计学意义(P0.05)。结论 1慢性应激抑郁模型大鼠脑内前额叶、海马、中缝核、伏隔核中5—HT1A受体m RNA表达均无变化;2慢性应激抑郁模型大鼠脑内海马、中缝核、伏隔核中5—HT2A受体m RNA表达均减少;在前额叶表达无变化。     

大鼠抑郁模型的脑磁共振成像研究

目的研究大鼠抑郁模型脑磁共振成像（ＭＲＩ）的变化。方法选择ＯＰＥＮＦＩＥＬＤ法评分相近的５０只成年ＳＤ雄性大鼠随机分为对照组和抑郁组,每组各２５只。应用分养和长期不可预见性中等强度应激所造成的大鼠抑郁模型。以敞箱实验等方法测定动物行为;ＭＲＩＴ２加权象对照研究抑郁大鼠脑内整体形态学及各脑区信号强度的改变。结果与对照组比较,抑郁组大鼠大脑纵裂深度加深［抑郁组（２．０５±０．１６）ｍｍ,对照组（１．８３±０．２１）ｍｍ,Ｐ＜０．０５］、体积扩大［抑郁组（３４３．００±７８．８７）ｍｍ３,对照组（２５８．００±１３．５９）ｍｍ３,Ｐ＜０．０５］。抑郁大鼠边缘系统各脑区Ｔ２加权象信号强度增加。结论提示抑郁大鼠存在脑萎缩,边缘系统各脑区水的流动性增加。     

脑卒中后抑郁大鼠海马齿状回5-羟色胺1A受体的表达

目的 观察脑卒中后抑郁(PSD)大鼠海马齿状回5-羟色胺1A(5-HT1A)受体的表达.方法 将SD雄性大鼠分为正常对照组、卒中组、应激抑郁对照组和PSD组,每组6只.应用左侧大脑中动脉阻塞(MCAO)联合不可预见的慢性温和应激(CMS)刺激及孤养法建立PSD大鼠模型,采用荧光实时定量聚合酶链反应和Western印迹法检测并比较各组大鼠CMS第19天和第28天齿状回5-HT1A受体(mRNA)和蛋白表达水平.结果 (1)CMS第19天,PSD组5-HT1A受体mRNA表达(O.012±0.001)低于正常对照组(0.361±0.010)和卒中组(0.039±0.002;P＜0.001);其5-HT1A受体蛋白表达(0.400±0.030)低于正常组(1.320±0.060)和卒中组(0.610±0.060;均P＜0.001).(2)CMS第28天,PSD组5-HT1A受体mRNA(0.013±0.001)低于正常对照组(0.336±0.011)、卒中组(0.063±0.006;均P＜0.001);其5-HT1A受体蛋白表达(0.080±0.020)低于正常组(0.620 ±0.030)、卒中组(0.260±0.040)和应激抑郁组(0.320±0.020;均P＜0.001).结论 PsD大鼠海马齿状回5-HT1A受体表达水平降低,此改变可能是PSD发病的分子机制之一.     

慢性应激大鼠中枢5-羟色胺含量及色氨酸羟化酶-2的表达变化

目的 探讨慢性不可预知轻度刺激（CUMS）大鼠模型中枢5-羟色胺（5-HT）含量和色氨酸羟化酶-2（TPH-2）的表达变化以及抗抑郁药的影响.方法 24只大鼠被随机分成3组,每组8只,A组为对照组,不给予刺激;B组为刺激不给药组,即CUMS应激鼠;C组为刺激给药组,即CUMS应激＋西酞普兰治疗组.实验为期6周,每周为大鼠称重,每3周测大鼠的糖水偏爱性,造模前后通过旷场试验评价大鼠行为,6周后对大鼠进行处死.处死后脑组织取样测定各脑区5-HT浓度及TPH-2 mRNA的表达水平.结果 经过6周干预,与A组比较,B组和C组体重明显降低（P＜0.05）;与A组及C组比较,B组糖水偏爱度显著降低（P＜0.05）,同时行为增多;B组5-HT浓度在海马中高于A组和C组,差异有统计学意义（P＜0.05）;在纹状体中,B组和C组5-HT浓度低于A组,差异有统计学意义（P＜0.05）;B组大鼠TPH2 mRNA在中缝核中表达低于A组,差异有统计学意义（P＜0.05）.结论 慢性应激可能引起中枢海马5-HT浓度增高及中缝核TPH-2表达降低,抗抑郁药可能引起中枢海马5-HT浓度降低,但未能影响中枢TPH-2的表达.     

慢性应激大鼠抑郁模型心肌纤维化改变及场电位变化的研究

目的 探讨慢性应激抑郁大鼠模型的心脏局部组织的病理及场电位变化.方法 Sprague-Dawley雄性大鼠20只,体质量180～250 g,随机分为抑郁组(10只)和对照组(10只).用Cronli方法 建立慢性轻度不可预见性应激抑郁模型,并对抑郁组大鼠在慢性应激前后进行糖水消耗试验和旷场行为测试.应用微电极阵记录技术观察大鼠的心率、心房及心室肌组织局部场电位时程(fAPD)的变化规律及左心室心尖部苏木素伊红HE染色和Massion染色.结果 (1)抑郁组大鼠慢性应激后心率[(107±18)次/min]显著高于对照组[(99±9)次/min]、心房肌组织fAPD[(83.1±4.6)ms]显著长于对照组[(45.8±3.7)ms],场电位离散度[(628±90)ms]大于对照组[(349±69)ms];(2)抑郁组心室肌局灶性炎症细胞浸润,心肌纤维间质胶原纤维增生.结论慢性应激大鼠抑郁模型心率、心房组织fAPD及其离散度的改变,是慢性应激致大鼠心肌炎症及心肌纤维化进而增加心肌组织电兴奋的离散度,这可能慢性抑郁性心律失常的基础.     

大鼠脑损伤后脑与血清中5—羟色胺和5—羟吲哚醋酸改变及…

本实验选用Ｗｉｓｔａｒ大鼠１００只，用荧光分光仪检测大鼠脑落体伤后不同时间脑皮质和血清中５－羟色胺（５－ＨＴ）及其代谢产物５－羟吲哚醋酸（５－ＨＩＡＡ）含量。并采用免疫组化（ＡＢＣ）法研究脑干中缝核群５－ＨＴ能神经元中５－ＨＴ合成及释放过程。同时，选择５－ＨＴ受体阻断剂赛庚啶治疗，观察其对５－ＨＴ及５－ＨＩＡＡ变化的影响。结果：脑损伤后脑皮质中５－ＨＴ和５－ＨＩＡＡ含量均明显升高。伤后６小时，５…     

卒中后抑郁大鼠模型的建立及评估

目的 建立卒中后抑郁（poststroke depression，PSD）有效动物模型。方法 大脑中动脉闭塞（MCAO）制备大鼠局灶脑缺血模型，加以慢性不可预见的温和刺激结合孤养建立PSD模型并予氟西汀干预。分为对照组、卒中组、抑郁组、PSD组和PSD+氟西汀组。分别采用糖水消耗试验、旷野试验（open-field test，OFT)、强迫游泳评估大鼠快感缺失、活动减少、行为绝望等行为。结果 应激14 d时，与对照组及卒中组相比，PSD组体重增长幅度显著降低（P<0.05），经氟西汀干预后体重增长幅度明显增加（P<0.01）。PSD组水平得分在应激第7天时与对照组相比显著降低（P<0.05）；到应激14 d时，PSD组与对照组及卒中组相比水平得分进一步下降（P<0.01），并持续到应激18 d（P<0.01）。PSD组垂直得分在应激14 d时与对照组、卒中组相比均显著下降（P<0.05或P<0.01），强迫游泳的不动时间明显延长（P<0.05）；而氟西汀干预后水平得分与垂直得分均显著增加（P<0.05或P<0.01），不动时间明显缩短（P<0.01）。结论 PSD模型大鼠较充分而持续表现快感缺乏、活动减少等“抑郁”核心症状，可操作性和重复性较好，是研究PSD较为理想的大鼠模型。氟西汀能改善PSD模型大鼠行为学异常。     

氯氮平对牛脑内多巴胺,5—羟色胺受体的药理学研究

为探索氯氮平抗精神病疗效的作用机制，采用放射配基受体结合分析法，以氚标记螺环哌啶酮为放射配基，通过受体饱和实验和竞争性抑制实验，分别研究小牛脑尾状核细胞膜Ｄ２受体和皮层额叶细胞膜５－羟色胺２（５－ＨＴ２）受体的最大结合容量、平衡解离常数、抑制药物５０％的浓度和竞争性抑制常数。实验结果表明，Ｓｃａｔｃｈａｒｄ和Ｈｉｌｌ分析提示，小牛尾状细胞膜Ｄ２受体结合位点有两处，相互间呈负协同作用，Ｓｒａｔｃｈａ     

色氨酸代谢对卒中后抑郁影响的研究

卒中后抑郁(PSD)是脑卒中患者常见的并发症,是一种以抑郁、情绪低落、认知功能障碍和兴趣下降为特征的精神疾病。PSD是由多种因素引起的,包括生物、心理和社会因素,但其发病机制尚不清楚。近年来,色氨酸代谢异常与PSD的相关性引起了广泛关注,卒中后在促炎细胞因子介导下调节色氨酸代谢被认为对PSD的发生中起着重要作用。本文就卒中后炎症反应对色氨酸分解代谢中的酶表达和活性及代谢产物的影响进而导致PSD的病理机制的研究进行综述。     

Involvement of hippocampal serotonin and neuropeptide Y in depression induced by chronic unpredicted mild stress

Accumulated evidence indicates a role of the hippocampal 5-hydroxy-tryptamine (5-HT) and neuropeptide Y (NPY) in the response to stress and modulation of depression, but it is unclear whether and how the hippocampal 5-HT and NPY systems make contributions to chronic unpredicted mild stress (CUMS)-induced depression. Here we observed that rats receiving a variety of chronic unpredictable mild stressors for 3 weeks showed a variety of depression-like behavioral changes, including a significant reduction in body weight, sucrose preference, and locomotion, rearing and grooming in open field test, and a significant increase in immobility time in forced swimming test. These CUMS-induced behavioral changes were suppressed or blocked by intra-hippocampal injection of 5-HT (31.25 μg/μl) or NPY (10 μg/μl). These data suggest a critical role of reduced hippocampal 5-HT and NPY neurotransmission in CUMS-induced depression.     

Effect of a chronic tryptophan dietary deficiency on the rat's sleep-wake cycle

The deep-wake cycle of 12 tiyptophan dietary deficient rats and their non-deficient paired controls were observed for a 8:00 a.m. to 8:00 p.m. period. EEG, EMG and body activity were continuously monitored on polygraphic recordings throughout the 12 hr observation period. The results indicate no significant difference between the tryptophan deficient and sufficient animals in time spent awake, slow-wave or paradoxical sleep. There was a non-significant trend among the tryptophan deficient animals to be less active and spend more time in both slow-wave and paradoxical sleep, which is in contrast to an expected insomnia effect. The results do not support the suggested relationship between reduced serotonin levels and the occurrence of insomnia, questioning the serotonergic theory of sleep.     

Changes in brain amines associated with cancer anorexia

Analysis of indole amine metabolism within acute (Walker 256 carcinosarcoma) and chronic (methycholanthrene-induced sarcoma) animal models of cancer anorexia demonstrated elevated levels of plasma free tryptophan, whole brain tryptophan, serotonin and 5-hydroxyindoleacetic acid in anorectic tumor-bearing rats. Whole brain levels of catecholamines were not changed within either tumor line. Regional central nervous system determination of tryptophan metabolism in rats bearing Walker 256 tumors revealed elevated tryptophan in the hypothalamus, corpus striatum, mesencephalon, diencephalon, cerebellum and cortex, increased serotonin in the diencephalon and cerebellum and elevated 5-hydroxyindoleacetic acid in the diencephalon, hippocampus, pons-medulla, cerebellum and cortex. Although tryptophan was significantly increased only in the corpus striatum and diencephalon of the more chronic methycholanthrene tumor model, serotonin concentration was elevated in the corpus stiratum, diencephalon, hippocampus, pons-medulla, cerebellum and cortex, while levels of 5-hydroxyindoleacetic acid were significantly increased in all these areas as well as in the mesencephalon. Since similar changes in indole activity were not observed in pair-fed control rats, it is concluded that the elevated serotonin and 5-hydroxyindoleacetic acid levels in tumor-bearing rats did not result from undernutrition alone. Assay of regional catecholamines revealed few food-relevant changes, with norepinephrine being elevated in the corpus striatum and decreased in the pons-medulla of tumor-bearing rats. Therefore, these experiments suggest that the increased serotonin metabolism observed in tumor-bearing rats may be involved in the etiology of the anorexia of cancer.     

Changes in brain amines associated with cancer anorexia

Analysis of indole amine metabolism within acute (Walker 256 carcinosarcoma) and chronic (methycholanthrene-induced sarcoma) animal models of cancer anorexia demonstrated elevated levels of plasma free tryptophan, whole brain tryptophan, serotonin and 5-hydroxyindoleacetic acid in anorectic tumor-bearing rats. Whole brain levels of catecholamines were not changed within either tumor line. Regional central nervous system determination of tryptophan metabolism in rats bearing Walker 256 tumors revealed elevated tryptophan in the hypothalamus, corpus striatum, mesencephalon, diencephalon, cerebellum and cortex, increased serotonin in the diencephalon and cerebellum and elevated 5-hydroxyindoleacetic acid in the diencephalon, hippocampus, pons-medulla, cerebellum and cortex. Although tryptophan was significantly increased only in the corpus striatum and diencephalon of the more chronic methycholanthrene tumor model, serotonin concentration was elevated in the corpus stiratum, diencephalon, hippocampus, pons-medulla, cerebellum and cortex, while levels of 5-hydroxyindoleacetic acid were significantly increased in all these areas as well as in the mesencephalon. Since similar changes in indole activity were not observed in pair-fed control rats, it is concluded that the elevated serotonin and 5-hydroxyindoleacetic acid levels in tumor-bearing rats did not result from undernutrition alone. Assay of regional catecholamines revealed few food-relevant changes, with norepinephrine being elevated in the corpus striatum and decreased in the pons-medulla of tumor-bearing rats. Therefore, these experiments suggest that the increased serotonin metabolism observed in tumor-bearing rats may be involved in the etiology of the anorexia of cancer.     

Effect of food restriction on the circadian rhythms of circulating tryptophan and serotonin in rats

Summary Male rats, kept under a lighting condition of 14 hours light and 10 hours dark were subjected to either ad libitum feeding or 50 per cent caloric restriction. At the end of 3 weeks, body weight and serum tryptophan (TRP) and serotonin (5 HT) were determined over a 24 hours period. It was found that the 40 per cent reduction in body weight was accompanied by a 10 per cent and a 39 per cent reduction in 24 hours mean serum TRP and 5 HT levels respectively. The timing of peak TRP and peak 5 HT levels was probably influenced by the timing of food presentation. Reduced food consumption led to lower peak and trough 5 HT levels but had no effect on peak or trough TRP levels.     

Tryptophan increases extracellular serotonin in the lateral hypothalamus of food-deprived rats

Although it is well established that increases in tryptophan availability can increase brain serotonin synthesis, the effect of tryptophan loads on serotonin release is not as clear. We have used in vivo microdialysis in order to monitor extracellular serotonin in the lateral hypothalamus to examine this issue. Tryptophan methyl ester (100 mg/kg IP) was administered to ad lib-fed and 48-h food-deprived rats. The results suggest that a peripheral tryptophan load can elevate extracellular serotonin in food-deprived subjects more effectively than in food-replete subjects.     

Expression analysis of genes responsible for serotonin signaling in the brain

To thoroughly understand the function and regulation of neurotransmitter systems in the brain, as well as the underlying disease mechanisms, it is important to comprehensively analyze the expression patterns of genes participating in such systems. Using functional annotated cDNA clones (FANTOM), we examined the gene expression patterns of the serotonin neurotransmitter system, which is involved in psychiatric diseases such as depression. We chose 24 gene products and visualized their endogenous localizations using in situ hybridization (ISH). We were able to fine-tune an automated ISH method to obtain high-resolution cell-based figures within 24 h. We also measured the amounts of mRNAs with quantitative RT-PCR. The outline of the in situ gene expression pattern viewed under low magnification agreed with the results of the RT-PCR. In the high-resolution view obtained with ISH, we could document novel localizations of the several genes critically related to serotonin activity.     

Evidence for decreased transport of tryptophan hydroxylase in Alzheimer''s disease

Tryptophan hydroxylase (TPH) is the rate-limiting enzyme in the synthesis of serotonin and a specific marker for serotonergic neurons. These neurons are affected in Alzheimer's disease (AD) in several ways: serotonin is decreased in axon terminals, serotonin neurons accumulate neurofibrillary protein, and these neurons are lost in AD brains. One subcellular mechanism which may underlie degeneration of neurons in AD is decreased axonal transport with accumulation of enzymes and their potentially toxic metabolites in the cell body. To determine whether there is a defect in axonal transport in serotonin neurons in AD we measured TPH activity, serotonin and its oxidative metabolite 5-hydroxyindoleacetic acid (5-HIAA) in dorsal raphe cell bodies from Alzheimer and control cases. TPH activity is increased 4.7-fold in raphe neuron cell bodies in Alzheimer brains. Serotonin and 5-HIAA are increased by 4.0- and 2.0-fold, respectively in Alzheimer compared to control raphe cell bodies. In contrast, in synaptic terminals of the amygdala 5-HT and 5-HIAA were decreased by 41% and 50%, respectively in the same AD cases. We propose that the accumulation of TPH and its products in the raphe perikarya in AD results from a diminished transport of TPH to axon terminals. The accumulation of oxidative metabolites of serotonin may contribute to the degeneration of serotonergic neurons in AD.     

Traumatic brain injury decreases serotonin transporter expression in the rat cerebrum

Objectives: An association has been postulated between traumatic brain injury (TBI) and depression. The serotonin transporter (SERT) regulates the concentration of serotonin in the synaptic cleft and represents a molecular target for antidepressants. We hypothesized that SERT expression in the brain changes following TBI.

Methods: We performed immunohistochemistry, real-time polymerase chain reaction analysis for mRNA and western blot analysis for protein to examine the time-dependent changes in SERT expression in the cerebrum during the first 14 days after TBI, using a controlled cortical impact model in rats.

Results: SERT immunoreactivity in neuronal fibres within the area adjacent to the cortical contusion decreased 1 to 14 days after injury. Significantly decreased SERT mRNA and protein expression were noted in the area adjacent to the cortical contusion 7 days after injury. There were no significant changes in SERT expression in the cingulum of the injured brain.

Discussion: The findings of this study indicate that TBI decreases SERT expression in the cerebral cortex. The decreased levels of SERT expression after TBI may result in decreased serotonin neurotransmission in the brain and indicate a possible relationship with depression following TBI.     

Low plasma tryptophan in carcinoid patients is associated with increased urinary cortisol excretion

BACKGROUND: Previously we observed in patients suffering from a metastatic carcinoid tumor that irritability, aggression and lack of impulse control are associated with low levels of plasma tryptophan and presumably with low brain serotonin function. In rats we showed that a diet of low tryptophan resulted in higher stress responses and higher corticosterone production. Here we tested in carcinoid patients whether tryptophan depletion due to tumor 5-HT overproduction is associated with high cortisol production. METHODS: Urinary excretion of cortisol, serotonin, 5-hydroxyindole acetic acid (the main metabolite of serotonin a marker of tumor activity), plasma levels of tryptophan and platelet content of serotonin (index of peripheral serotonin synthesis) were determined in metastatic midgut carcinoid patients. Patients (N=25) were divided into two groups based on their plasma tryptophan levels (/=49mumol/l, n=13). RESULTS: Carcinoid patients with low plasma tryptophan levels had significantly higher urinary excretion of free cortisol (p<0.01), independent of tumor activity. The inter-individual differences in the low tryptophan group, however, were substantial. CONCLUSIONS: In a subgroup of the patients suffering from metastatic carcinoid disease the cerebral access of plasma tryptophan is impaired, thus rendering cerebral serotonin neurotransmission suboptimal and leading to hypercortisolism. The present study provides further support to the idea that low serotonergic function is a risk for developing stress-associated psychopathology.