自杀行为与色氨酸羟化酶的研究进展

绝大多数抑郁症和自杀的生化研究表明5-羟色胺(5-HT)是与抑郁症和自杀有关的关键性神经递质。色氨酸羟化酶 (TPH) 是5-HT生物合成的限速酶，本文对TPH及其基因多态性在自杀发病机制中所起作用的研究现况和进展作一综述。     

色氨酸羟化酶2在更年期抑郁症模型大鼠中缝核中表达减少

目的 观察更年期抑郁症大鼠模型海马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SD大鼠,在卵巢切除术的基础上,联合孤养和21d慢性不可预见性温和刺激（CUMS）制备更年期抑郁症大鼠模型,以行为学测试进行评价。用高效液相色谱-电化学法（(HPLC-ECD）测定海马5-HT含量;用RT-PCR技术检测中缝核TPH2 mRNA表达量;用荧光免疫组化检测中缝核TPH2蛋白表达。结果 21d应激后,模型组大鼠直立活动得分及水平活动得分均减少,糖水消耗百分比下降;海马5-HT含量下降;中缝核TPH2 mRNA表达量及TPH2阳性神经元数量减少。结论 在卵巢切除术的基础上,联合孤养和21d CUMS可造成更年期抑郁症大鼠模型;模型大鼠海马5-HT含量下降,可能是中缝核TPH2的表达减少所致。     

色氨酸羟化酶2在去卵巢抑郁症模型大鼠中缝核中表达减少

目的 观察去卵巢抑郁症大鼠模型海马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SD大鼠,在卵巢切除术的基础上,联合孤养和21 d慢性不可预见性温和刺激(CUMS)制备去卵巢抑郁症大鼠模型,以行为学测试进行评价.用高效液相色谱-电化学法((HPLC-ECD)测定海马5-HT含量;用RT-PCR技术检测中缝核TPH2 mRNA表达量;用荧光免疫组化检测中缝核TPH2蛋白表达.结果 21 d应激后,模型组大鼠直立活动得分及水平活动得分均减少,糖水消耗百分比下降;海马5-HT含量下降;中缝核TPH2 mRNA表达量及TPH2阳性神经元数量减少.结论 在卵巢切除术的基础上,联合孤养和21 d CUMS可造成去卵巢抑郁症大鼠模型;模型大鼠海马5-HT含量下降,可能是中缝核TPH2的表达减少所致.     

左旋多巴对大鼠中脑5羟色胺能神经元的影响

目的:观察左旋多巴对大鼠脑内5羟色胺(5-HT)能神经元的影响.方法:左旋多巴大鼠灌胃,以免疫细胞化学和流式细胞术显示5-HT及色氨酸羟化酶(TPH)免疫反应物质或含量的变化.结果:免疫细胞化学显示左旋多巴组大鼠中缝背核5-HT能神经元细胞直径明显小于对照组;中缝背核5-HT和TPH免疫反应物质灰度值比对照组分别增高了7.72%和16.57%.流式细胞术显示左旋多巴组5-HT的表达量比对照组减少了18.45%,TPH表达量比对照组减少了19.90%.结论:左旋多巴降低脑内5-HT能神经元5-HT和TPH的表达.     

大鼠多重脑震荡后脑内TPH表达变化

目的:探讨多重脑震荡(multiple cerebral concussion,MCC)后脑内5-HT能神经元内色氨酸羟化酶(tryptophan hydroxylase,TPH)含量的变化。方法:42只雄性大鼠随即分为7组,每组6只,一组为对照组,其余的大鼠用金属单摆式机械打击装置复制MCC大鼠模型,伤后分1~24 d不同时段的6个损伤组,用免疫组化技术和图像分析方法观察基底前脑及脑干5-HT能神经元内TPH含量的变化。结果:多重脑震荡后2~8 d上述脑区TPH免疫阳性表达升高(P<0.05),伤后24 d趋于正常(P>0.05)。结论:多重脑震荡后5-HT神经元TPH表达增强,可能与脑损伤后神经元的应激反应有关。     

增强5-羟色胺能神经元活动对激光穴位刺激镇痛作用的影响

本实验采用5-HT的前体物质L-色氨酸或提高脑内5-HT含量的胰岛索对家兔或绵羊进行静脉注射,然后用CO_2激光或He-Ne激光刺激动物腰荐十字部“百会”穴,应用钾离子透入法测取痛阈,观察它们对激光穴位刺激镇痛作用的影响。结果表明,L-色氨酸和胰岛素均能显著提高家兔或绵羊激光穴位刺激镇痛效果,提示5-羟色胺能神经元及其介质5-HT也参与激光穴位刺激镇痛。     

孕期脂多糖诱导的孤独症样大鼠肠道5-羟色胺相关代谢通路的变化

目的：探讨孕期脂多糖(LPS)诱导的孤独症样子代大鼠肠道5-羟色胺(5-HT)相关代谢通路的变化。方法：将20只SD大鼠随机平分为LPS组和磷酸盐缓冲液(PBS)组(n=10),分别在怀孕9.5 d时腹腔注射LPS(100μg/kg)和等体积PBS,所产子代大鼠即为LPS组(n=60)和PBS组(n=60)。采用三箱社交实验和旷场实验检测子代大鼠社会交往能力和重复刻板行为。检测粪便含水量和胃肠转运时间以评估子代大鼠肠道蠕动功能。ELISA检测子代大鼠血清二胺氧化酶(DAO)、IgA和5-HT含量,以及粪便IgA含量。转录组学及色氨酸靶向代谢组学分析子代大鼠结肠组织、16S多样性检测子代大鼠粪便中肠道微生物菌群变化。Western blot技术测定子代大鼠结肠组织色氨酸羟化酶1(TPH1)和TPH2的表达水平。结果：孕期LPS处理可诱导子代大鼠出现孤独症样行为,并导致粪便含水量增加(P<0.01),胃肠转运时间和结肠转运时间缩短(P<0.01)。同时观察到LPS组子代大鼠血清5-HT、DAO和IgA含量及粪便IgA含量均有升高趋势。转录组学富集到色氨酸代谢通路以及犬尿酸相关通...     

5-羟色胺系统参与学习记忆调节的研究进展

5-羟色胺（5-HT）系统在学习记忆中的调控作用越来越受到关注。5-HT能神经元是学习记忆研究最主要的神经元之一。5-HT释放作用于突触前/后膜各种亚型受体发挥其功能,尤其是对5-HT能神经元投射环路深入研究,将促进对学习记忆的探究。本文对5-HT受体、5-HT能神经元活动水平、5-HT能神经元投射环路参与学习记忆的相关研究进行阐述,为治疗学习记忆障碍提供理论依据。     

新疆维吾尔族群体色氨酸羟化酶1基因T3804A位点多态性与抑郁症的关联

目的探讨新疆维吾尔族群体色氨酸羟化酶1(TPH1)基因T3804A(rs623580)位点多态性与抑郁症的关系。方法采用聚合酶链式反应产物直接测序的方法检测104例抑郁症患者(研究组)和90例正常体检者(对照组)TPH1基因rs623580位点的基因型。应用SPSS10.0分析基因多态性与抑郁症相关性。结果研究组与对照组TPH1基因rs623580位点的基因型频率差异(χ2=6.560,P=0.038)和等位基因频率差异(χ2=5.517,P=0.019)具有统计学意义。研究组与对照组按性别分亚组,女性研究组与对照组基因型频率差异(χ2=8.026,P=0.018)和等位基因频率差异(χ2=7.154,P=0.007)具有统计学意义。男性研究组与对照组基因型频率差异和等位基因频率差异不具有统计学意义。结论新疆维吾尔族群体色氨酸羟化酶1基因T3804A位点与抑郁症的发病可能具有关联性,A等位基因可能是抑郁症的易感基因。     

脑损伤后5-HT能神经变化与认知障碍的研究进展

创伤性脑损伤是仅次于肢体损伤的常见的人体损伤。认知功能障碍是脑损伤后较常见的并发症。研究发现,脑损伤后认知功能的改变与伤后脑内胆碱能、单胺能等神经递质的变化有关。本文就脑损伤对5-羟色胺（5-hydroxytryptamine,5-HT）能神经系统及认识障碍的影响及其相互关系做一综述。     

Immunohistochemistry of tryptophan hydroxylase in the rat brain

An antiserum raised against tryptophan tetrahydropterine oxygen oxidoreductase was used to examine in rat brain the immunohistochemical localization of this rate-limiting enzyme catalysing the biosynthesis of serotonin. Tryptophan tetrahydropterine oxygen oxidoreductase was detected in numerous nerve cell bodies, proximal dendrites and axon varicosities or terminals corresponding to those of serotonin neurons as judged by their anatomical distribution and concomitant immunoreactivity to an antiserum against serotonin. In hypothalamus, a serotonin-containing nerve cell group previously visualized in the pars ventralis of the nucleus dorsomedialis by radioautography after serotonin uptake, and by serotonin immunohistochemistry after tryptamine loading, remained tryptophan tetrahydropterine oxygen oxidoreductase-unreactive even in rats treated with colchicine. On the other hand, a small group of tryptophan tetrahydropterine oxygen oxidoreductase-positive cells was identified in the rostrolateral portion of nucleus dorsomedialis, which could play a part in the intrinsic serotonin innervation of hypothalamus. There was no overlap between tryptophan tetrahydropterine oxygen oxidoreductase immunostaining and the cellular distribution of N-acetyl serotonin as reported in earlier studies. It is therefore likely that the synthesis of N-acetyl serotonin from tryptophan does not take place in N-acetyl serotonin-containing neurons.     

Development by environment interactions controlling tryptophan hydroxylase expression

Tryptophan hydroxylase is the rate-limiting enzyme in the biosynthesis of serotonin (5-hydroxytryptamine; 5-HT). Two isoforms of tryptophan hydroxylase, derived from different genes, tph1 and tph2, have been identified. The tph1 isoform is expressed in peripheral tissues, whereas tph2 is brain and neuron-specific. Recent studies suggest that tph2 expression and brain serotonin turnover are upregulated in depressed suicide patients, and drug-free depressed patients, respectively. Increased tph2 expression could result from genetic influences, early life developmental influences, adverse experience during adulthood, or interactions among these factors. Studies in rodents support the hypothesis that interactions between early life developmental influences and adverse experience during adulthood play an important role in determining tph2 expression. In this review, we highlight the evidence for the effects of adverse early life experience and stressful experience during adulthood on both tph1 and tph2 expression.     

Childhood-onset schizophrenia and tryptophan hydroxylase gene polymorphism.

We explored the relationship between the tryptophan hydroxylase gene polymorphism and susceptibility to childhood-onset schizophrenia in a Japanese sample. Subjects were 51 Japanese patients who met DSM-IV criteria for schizophrenia before age 16 and 148 Japanese healthy controls. DNA was extracted from whole blood and genotyping was performed by PCR-RFLP using Nhe I. The frequency of the A allele was relatively higher in patients with childhood-onset schizophrenia than in controls (odds ratio, OR = 1.47, 95% CI = 0.97-2.37, P = 0.097). There was a nearly doubling of the risk for childhood-onset schizophrenia associated with the AA genotype compared to other genotype groups; OR = 1.97, 95% CI = 0.91-4.22, P = 0.058.     

Immunochemical characterization of brain and pineal tryptophan hydroxylase

Recombinant mouse tryptophan hydroxylase (TPH) was expressed in Escherichia coli, using a bacterial expression vector and has been purified to homogeneity by sonication followed by Sepharose 4B column chromatography and native slab gel electrophoresis. This purified enzymatically active TPH protein was used for production of a specific antiserum. This antiserum identified the predicted TPH band (molecular weight, 54 kDa) on Western blot of crude extracts from the rat and mouse dorsal raphe, and the rat pineal gland. However, this antiserum recognized an additional protein band of lower molecular weight (48 kDa) in pineal extract. It is not clear whether the 48 kDa TPH band represents an isozyme or a protease cleavage product of TPH. Since the pineal gland contains higher TPH mRNA and lower TPH activity when it is compared with dorsal raphe nucleus enzyme, this lower molecular weight TPH may participate in the reduced TPH specific activity. In addition, there are no specific TPH inhibitors in the pineal gland and this lower molecular weight TPH is inactive or has a very low specific activity. This antiserum specifically immunostained serotonergic cell bodies in the dorsal raphe nuclei, some large caliber serotonergic processes in the dorsal raphe area as well as terminals in the olfactory bulb. It also immunolabeled the pineal gland and immunoprecipitated equally well TPH protein from the dorsal raphe nucleus and the pineal gland in a concentration-dependent manner.     

Correlation between brain tryptophan hydroxylase activity and catalepsy in mice

Laboratory of Phenogenetics of Behavior, Institute of Cytology and Genetics, Siberian Branch, Academy of Sciences of the USSR, Novosibirsk. (Presented by Academician of the Academy of Medical Sciences of the USSR V. A. Matyukhin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 108, No. 9, pp. 269–271, September, 1989.     

Association study of tryptophan hydroxylase 2 gene polymorphisms in panic disorder

Experimental studies on serotonin (5-HT) availability suggest a role for 5-HT synthesis rate in panicogenesis. Recently, it has been discovered that the tryptophan hydroxylase gene isoform 2 (TPH2), rather than TPH1, is preferentially expressed in the neuronal tissue and, therefore, is primarily responsible for the regulation of brain 5-HT synthesis. In the present case-control genetic association study we investigated whether panic disorder (PD) phenotypes are related to two single nucleotide polymorphisms (SNP) of TPH2, rs1386494 A/G and rs1386483 C/T. The study sample consisted of 213 (163 females and 50 males) PD patients with or without affective comorbidity and 303 (212 females and 91 males) matched healthy control subjects. The allelic and genotypic analyses in the total sample did not demonstrate significant association of PD with the studied SNPs, suggesting that these polymorphisms may not play a robust role in predisposition to PD. However, an association with rs1386494 SNP was observed in the subgroup of female patients with pure PD phenotype, indicating a possible gender-specific effect of TPH2 gene variants in PD.     

Functional properties of missense variants of human tryptophan hydroxylase 2

Tryptophan hydroxylase 2 (TPH2) catalyzes the rate‐limiting step in serotonin biosynthesis in the nervous system. Several variants of human TPH2 have been reported to be associated with a spectrum of neuropsychiatric disorders such as unipolar major depression, bipolar disorder, suicidality, and attention‐deficit/hyperactivity disorder (ADHD). We used three different expression systems: rabbit reticulocyte lysate, Escherichia coli, and human embryonic kidney cells, to identify functional effects of all human TPH2 missense variants reported to date. The properties of mutants affecting the regulatory domain, that is, p.Leu36Val, p.Leu36Pro, p.Ser41Tyr, and p.Arg55Cys, were indistinguishable from the wild‐type (WT). Moderate loss‐of‐function effects were observed for mutants in the catalytic and oligomerization domains, that is, p.Pro206Ser, p.Ala328Val, p.Arg441His, and p.Asp479Glu, which were manifested via stability and solubility effects, whereas p.Arg303Trp had severely reduced solubility and was completely inactive. All variants were tested as substrates for protein kinase A and were found to have similar phosphorylation stoichiometries. A standardized assay protocol as described here for activity and solubility screening should also be useful for determining properties of other TPH2 variants that will be discovered in the future. Hum Mutat 30:1–8, 2009. © 2009 Wiley‐Liss, Inc.     

Meta-analysis of the association between tryptophan hydroxylase and suicidal behavior

Tryptophan hydroxylase (TPH) has been the candidate gene of focus in many of the association studies of suicidal behavior in recent years. Initial positive findings with respect to an association between the TPH gene and suicidal behavior have been replicated, but not consistently. Typically, individual studies have investigated small samples, and thus they repeatedly had insufficient statistical power to detect a positive association. Meta-analysis is one approach that can be used to achieve greater statistical power and may be helpful in providing a more conclusive understanding. We used meta-analytic techniques to investigate the association between an intron 7 polymorphism in the TPH gene and suicidal behavior. A total of 39 publications were identified and reviewed, 17 of which were selected for inclusion in this study. We performed two meta-analyses. One compared suicide attempters or completers (N = 1,290) with healthy controls (N = 2,295); the other compared suicide attempters (N = 625) with nonattempters (N = 1,475). None of these studies provided evidence for association (odds ratio (OR) = 1.14, 95% confidence interval (CI) = 0.97-1.34 for the former and OR = 0.96, 95% CI = 0.77-1.20 for the latter). The combined results from comparisons within both groups showed no overall association between suicidal behavior and an intron 7 polymorphism of the TPH gene.