Verbascoside promotes the regeneration of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra

Tyrosine hydroxylase is a key enzyme in dopamine biosynthesis. Change in tyrosine hydroxylase expression in the nigrostriatal system is closely related to the occurrence and development of Parkinson＇s disease. Verbascoside, an extract from Radix Rehmanniae Praeparata has been shown to be clinically effective in treating Parkinson＇s disease. However, the underlying mechanisms remain unclear. It is hypothesized that the effects of verbascoside on Parkinson＇s disease are related to tyrosine hydroxylase expression change in the nigrostriatal system. Rat models of Parkinson＇s disease were established and verbascoside（60 mg/kg） was administered intraperitoneally once a day. After 6 weeks of verbascoside treatment, rat rotational behavior was alleviated; tyrosine hydroxylase m RNA and protein expression and the number of tyrosine hydroxylase-immunoreactive neurons in the rat right substantia nigra were significantly higher than the Parkinson＇s model group. These findings suggest that the mechanism by which verbascoside treats Parkinson＇s disease is related to the regeneration of tyrosine hydroxylase-immunoreactive neurons in the substantia nigra.

Tyrosine Hydroxylase as a Target for Deltamethrin in the Nigrostriatal Dopaminergic Pathway

Objective To study the effects of deltamethrin on tyrosine hydroxylase in nigrostriatum of male rats. Methods Sprague-Dawley rats were daily treated with deltamethrin at 6.25 or 12.5 mg/kg body weight by gavage for 10 days. Then HPLC-fluorescence detection was used to analyze the contents of dopamine （DA）, 3,4-dihydmxyphenylacetic acid （DOPAC） and homoranillic acid （HVA） in substantial nigra and striatum. The activities of tyrosine hydroxylase （TH） were also detected by HPLC-fluorescence detection. TH mRNA or TH protein levels were measured by RT-PCR and immunohistochemistry method. Results The content of DA in stfiatum was significantly decreased by the treatments, suggesting an inhibition of DA synthesis by deltamethrin. The contents of DA metabolites DOPAC and HVA increased, indicating increased dopamine turnover. Furthermore, deltamethrin significantly decreased the activity, as well as the mRNA and protein levels of TH. Conclusions These findings reveal a novel aspect of deltamethfin neurotoxicity and suggest tyrosine hydroxylase as a molecular target of deltamethin on dopamine metabolism in the nigrostriatal pathway.

Tyrosine hydroxylase expression in the midbrain of Parkinson's disease model rats treated with Xifeng Dingchan decoction

This study showed that abnormal behavioral changes were greatly improved in rats displaying Parkinson＇s disease-like symptoms after intragastric administration of Xifeng Dingchan decoction at 15, 7.5, 3.75 g/kg per day. In addition, tyrosine hydroxylase mRNA expression in the substantia nigra of the midbrain was up-regulated, and tyrosine hydroxylase content in the midbrain ventral tegmentum and substantia nigra pars compacta was also increased. The effect of administration of Xifeng Dingchan decoction at 7.5 g/kg per day was similar to that of Madopar at 67.5 mg/kg per day. These results indicate that the therapeutic effect of Xifeng Dingchan decoction on Parkinson＇s disease is associated with the up-regulated protein and mRNA expression of tyrosine hydroxylase in the midbrain.

Treatment time influences the effects of a low-frequency pulsed electric field on synthesis of tyrosine hydroxylase and dopamine in PC12 cells

BACKGROUND： Electromagnetic radiation can influence dopamine （DA） synthesis in brain tissues or ceils, but electromagnetic frequencies, intensities, and radiation time can produce different effects. In addition, the signal pathway by which electromagnetic radiation influences DA synthesis remains controversial. OBJECTIVE： To determine tyrosine hydroxylase （TH） expression in PC12 cells and DA levels in cell culture media after different periods of low-frequency pulsed electric field （LF-PEF） stimulation, and to determine how LF-PEF signaling stimulates TH synthesis using inhibitors. DESIGN, TIME AND SETTING： A parallel, controlled, cell experiment was performed at the Laboratory of Cell Biology, School of Life Science, East China Normal University, between January and October 2006. MATERIALS： PC12 cells were purchased from the Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, China. Nerve growth factor was purchased from PeproTech, USA. The protein kinase A inhibitor, H-89, and mitogen-activated protein kinase kinase inhibitor, U0126, were purchased from Sigma, USA. METHODS： （1） Following routine culture in Dulbecco＇s modified eagle medium, primary PC12 cells were stimulated under LF-PEF （pulse frequency 50.Hz, pulse width 20 μs, peak field strength 1 V/m） for 5, 10, 15, 20, and 30 minutes. （2） Inhibitors （H-89 or U0126, 1 μmol/L） were added 30 minutes before LF-PEF stimulation for 10 minutes. MAIN OUTCOME MEASURES： （1） TH expression was determined by Western blot in PC12 cells at 0.5, 1,2, 3, and 4 days after LF-PEF stimulation. Similarly, DA was measured by high-performance liquid chromatography in media at 2, 3, 4, or 5 days after LF-PEE （2） TH expression was detected 1 day after H-89 or U0126 treatment and LF-PEE RESULTS： （1） Short-term LF-PEF stimulation （5 and 10 minutes） increased TH expression and media DA levels after short-term culture （2 days） （P 〈 0.01）, but both parameters decreased with longer culture （3 4 days） （P 〈 0.01）. Long-term LF-PEF stimulation （15, 20, or 30 minutes） decreased TH and DA synthesis, followed by a rapid increase （P 〈 0.01）. （2） H89 could completely inhibit TH expression in PC12 cells stimulated by LF-PEF for 10 minutes, while the inhibition rate of U0126 was 53.2%. CONCLUSION： Short-term LF-PEF first promotes then inhibits, while long-term LF-PEF first inhibits then promotes, TH and DA synthesis. LF-PEF stimulation regulates TH expression primarily by activating protein kinase A to regulate DA synthesis.

Tyrosine hydroxylase and Lewy body molecules immunoreactivity in the SNC neurons of an AS/AGU mutantrat

The AS/AGU rat has a recessive single point mutation in the gene coding for the gamma isoform of protein kinase C (PKC-γ) resulting in a failure to release dopamine in the striatum and impaired movement including a staggering gait, difficulty in initiating movement and a slight whole body tremor. This study examined the levels tyrosine hydroxylase, ubiquitin and parkin in individual SNC cell bodies, there was no evidence of a reduction in tyrosine hydroxylase levels although levels of ubiquitin and parkin were elevated in the cytoplasm. The findings support the hypothesis that the initial bar to dopamine availability in the striatum is reduced release, with substantia nigra cell death being a later phenomenon.

COEXISTENCE OF FOS-LIKE PROTEIN IN TYROSINE HYDROXYLASE-LIKE IMMUNOREACTIVE NEURONS IN THE HINDBRAIN OF ARTS FOLLOWING PERIPHERAL ELECTRICAL STIMULATION

In the present study we have found that proto-oncogene c-fos protein can expressin the noradrenergic neurons of rat hindbrain following peripheral electrical stimulation. Ratswere given peripheral electrical stimulation via thin stainless steel pins inserted into the pointsnear knee joint (S36) and ankle joint (Sp6) which mimic the manipulation of electroacupuncture(EA) performed in humans. Animals were perfused for double staining immunohistochemistry 2hafter the termination of EA. In rats subjected to EA stimulation Fos-like protein was found in thetyrosine hydroxylase (TH)-like immunoreactive neurons in rat hindbrain. The Fos and TH coex-isting neurons were distributed in the locus coeruleus, solitary tract nucleus, ventrolateral medul-la, periaqeductal gray, as well as superior colliculus. The percentage of the coexisting neuronscompared with the total number of neurons containing Fos-like protein in these nuclei rangedfrom 6% to 32%. The results suggest that the noradrenergic neurons in these regions may be ac-tivted by acupuncture stimulation.

Tyrosine hydroxylase gene transfections to different sites of striatum in the rat model of Parkinson’s disease

The use of gene therapy has been intensively studied as a potential method to treat Parkinson’s disease (PD) and other degenerative brain diseases. However, the effects of experimental measures and approaches on the outcome of gene delivery or on the physiological state of target tissues have not been analyzed as much and systematically. Therefore, we have infused adenovirus vectors expressing either a therapeutic tyrosine hydroxylase (TH) gene or a lacZ reporter gene into striatum in a rat model of PD. The experimental procedures were tested using the Ad lacZ vector in order to optimize concentrations, volumes, infusion speeds and transfection times. The expression of Ad lacZ vector was lower and declined earlier in the lesioned than unlesioned striatum suggesting that the lesion affects on the transfection efficiency and outcome of gene transfection. The effect of three different approaches of Ad TH vector transfection was compared: 1) the delivery of Ad TH gene vector alone into one single site of striatum, 2) the delivery of Ad TH gene vector alone into multiple sites of striatum, and 3) the delivery of Ad TH gene vector into one site of striatum followed by a continuous infusion of tetrahydrobiopterin (BH4) cofactor with a mini pump. There was a small and transient unsignificant decrease in the turning behavior when the Ad TH vector was delivered into one site of the striatum. Simultaneous infusion into several sites or together with BH4 cofactor did not improve more the effect of gene delivery. Thus, although the effects were unsignificant, the Ad TH transfection seemed to decrease the turning behavior in the rat model of PD and the optimal effect was seen at some specific doses and time points. Furthermore, the outcome of gene therapy could depend in addition to the amount and efficacy of gene vectors also on the physiological state and experimental strategies.

Dark rearing maintains tyrosine hydroxylase expression in retinal amacrine cells following optic nerve transection

The present study examined changes in retinal tyrosine hydroxylase （TH） expression in rats having undergone optic nerve transection and housed under a normal day/night cycle or in the dark. The aim was to investigate the effects of amacrine cells on axonal regeneration in retinal ganglion cells and on the synapses that transmit visual signals. The results revealed that retinal TH expression gradually decreased following optic nerve transection in rats housed under a normal day/night cycle reaching a minimum at 5 days. In contrast, retinal TH expression decreased to a minimum at 1 day following optic nerve transection in dark reared rats, gradually increasing afterward and reaching a normal level at 5 7 days. The number of TH-positive synaptic particles correlated with the TH levels indicating that dark rearing can help maintain TH expression during the synaptic degeneration stage （5 7 days after optic nerve injury） in retinal amacrine cells.

TH基因变异致多巴反应性肌张力障碍二例

例1女性,8岁,主因独立行走不能6年余,于2011年8月10日至我院神经内科门诊就诊。患儿于出生后约15月龄时(2004年10月)受凉后发热(约39℃)而出现肢体活动差,表现为四肢活动减少,独自站立不能,症状呈进行性加重,尤以受凉、上呼吸道感染后症状明显加重。2岁时仍无法独立行走,需他人扶行,并出现四肢关节挛缩,症状有日间波动性,晨轻暮重。曾于外院就诊,具体检查和诊断不详,未予治疗。家属诉患儿出生史及1岁以内语言、运动等生长发育史均正常;父母非近亲婚配,否认家族中有类似疾病病史。

CHCHD2 Thr61Ile mutation impairs F1F0-ATPase assembly in in vitro and in vivo models of Parkinson's disease

Mitochondrial dysfunction is a significant pathological alte ration that occurs in Parkinson's disease(PD),and the Thr61lle(T61I)mutation in coiled-coil helix coiled-coil helix domain containing 2(CHCHD2),a crucial mitochondrial protein,has been reported to cause Parkinson's disease.FIFO-ATPase participates in the synthesis of cellular adenosine triphosphate(ATP)and plays a central role in mitochondrial energy metabolism.However,the specific roles of wild-type(WT)CHCHD2 and T611-mutant CHCHD2 in regulating F1FO-ATPase activity in Parkinson's disease,as well as whether CHCHD2 or CHCHD2 T61I affects mitochondrial function through regulating F1FO-ATPase activity,remain unclea r.Therefore,in this study,we expressed WT CHCHD2 and T61l-mutant CHCHD2 in an MPP^(+)-induced SH-SY5Y cell model of PD.We found that CHCHD2 protected mitochondria from developing MPP^(+)-induced dysfunction.Under normal conditions,ove rexpression of WT CHCHD2 promoted F1FO-ATPase assembly,while T61I-mutant CHCHD2 appeared to have lost the ability to regulate F1FO-ATPase assembly.In addition,mass spectrometry and immunoprecipitation showed that there was an interaction between CHCHD2 and F1FO-ATPase.Three weeks after transfection with AAV-CHCHD2 T61I,we intraperitoneally injected 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine into mice to establish an animal model of chronic Parkinson's disease and found that exogenous expression of the mutant protein worsened the behavioral deficits and dopaminergic neurodegeneration seen in this model.These findings suggest that WT CHCHD2 can alleviate mitochondrial dysfunction in PD by maintaining F1F0-ATPase structure and function.

A RAPID FLUORIMETRIC DETERMINATION OF TYROSINE IN SERUM BY THE REACTION WITH CERIUM (Ⅳ)

A fluorimetric method for the determination of tyrosine in serum was proposed. The fluoriscence intensity is a linear function of tyrosine content in the range 0-1. 44ug/ml. The percentage of recovery was satisfactory.

刮痧对鱼藤酮诱导的帕金森病大鼠行为学及黑质区TH水平和炎症因子的影响

目的观察刮痧对鱼藤酮诱导的帕金森病(PD)模型大鼠行为学及黑质酪氨酸羟化酶(TH)、核因子κB(NF-κB)、γ干扰素(IFN-γ)、白细胞介素-1β(IL-1β)的影响,探究刮痧干预PD可能的作用机制。方法32只SD雄性大鼠随机分为假手术组、模型组、药物组和刮痧组,每组8只。模型组、药物组和刮痧组大鼠采用颈背部皮下注射鱼藤酮(1 mg·kg^(-1))建立PD大鼠模型。药物组每天给予美多芭灌胃(50 mg·kg^(-1)),刮痧组隔日刮痧1次,刮12次,共计23 d。造模前、造模后、干预结束观察大鼠行为学改变;干预结束,采用Western blot和免疫荧光检测黑质区TH表达,免疫组化法检测黑质TH、NF-κB表达,ELISA法检测中脑黑质NF-κB、IFN-γ、IL-1β含量,HE染色观察纹状体区细胞形态。结果与假手术组相比,模型组大鼠行为学评分(3.42±1.248),5 min内运动总距离缩短(P<0.0001),起点停留时间延长(P<0.05),悬尾5 min内静止时间明显延长(P<0.001),中脑黑质TH表达减少(P<0.001),黑质NF-κB、IFN-γ、IL-1β含量均增加(P<0.0001),纹状体区细胞肿胀明显(P<0.05)。与模型组相比,刮痧组大鼠5 min内运动总距离增加(P<0.05)、起点停留时间缩短(P<0.05)、悬尾5 min内静止时间缩短(P<0.05),黑质区TH表达增加(P<0.05),黑质NF-κB、IFN-γ、IL-1β含量均下降(P<0.05),纹状体区细胞肿胀情况改善(P<0.0001)。刮痧组与药物组相比,各项指标差异均无统计学意义。结论刮痧可改善鱼藤酮诱导的PD大鼠的运动功能障碍,其机制可能与下调炎性因子表达,抑制神经炎性反应,减少多巴胺能神经元丢失,发挥神经保护作用有关。

A core-satellite-like nanoassembly reverses a decisive tyrosine hydroxylase loss in degenerative dopaminergic neurons

In recent years,neurodegenerative diseases,such as Parkinson’s or Alzheimer’s diseases,are rapidly rising in prevalence.The main hallmark of Parkinson’s disease is the falling levels of neurotransmitter dopamine in the mid-brain with dopaminergic neurons losing.Typical therapeutic solutions,including drugs,deep brain stimulation,and cell transplantation,can only alleviate the symptoms of Parkinson’s disease.It is a tremendous challenge to reverse the function degeneration of the crucial dopaminergic neurons.Herein,we develop a core-satellite-like nanoassembly(PDA-AFn(by integrating polydopamine nanoparticles and apoferritin))to raise the expression of tyrosine hydroxylase(TH),a rate-limiting enzyme in the formation of the dopamine.Both components in the nanoassembly could cooperate with each other,not only elaborately regulate the iron homeostasis and redox microenvironment,but also utilize excessive reactive oxygen species(ROS)and iron ions in the damaged neurons to supply extra dopamine and enhance TH activity,and consequently restore the function of the degenerated neurons.Remarkably,the nanoassembly-treatment relieves the dyskinesia and dramatical increases the tyrosine hydroxylase and dopamine level in the midbrain of Parkinson’s disease model mice.It is an explicit yet inspiring advance in treatment of the neurodegeneration.

Single-nuclei RNA sequencing uncovers heterogenous transcriptional signatures in Parkinson's disease associated with nuclear receptor-related factor 1 defect

Previous studies have found that deficiency in nuclear receptor-related factor 1(Nurr1),which participates in the development,differentiation,survival,and degeneration of dopaminergic neurons,is associated with Parkinson s disease,but the mechanism of action is perplexing.Here,we first asce rtained the repercussion of knocking down Nurr1 by pe rforming liquid chromatography coupled with tandem mass spectrometry.We found that 231 genes were highly expressed in dopaminergic neurons with Nurr1 deficiency,14 of which were linked to the Parkinson’s disease pathway based on Kyoto Encyclopedia of Genes and Genomes analysis.To better understand how Nurr1 deficiency autonomously invokes the decline of dopaminergic neurons and elicits Parkinson’s disease symptoms,we performed single-nuclei RNA sequencing in a Nurr1 LV-shRNA mouse model.The results revealed cellular heterogeneity in the substantia nigra and a number of activated genes,the preponderance of which encode components of the major histocompatibility Ⅱ complex.Cd74,H2-Ab1,H2-Aα,H2-Eb1,Lyz2,Mrc1,Slc6α3,Slc47α1,Ms4α4b,and Ptprc2 were the top 10 diffe rentially expressed genes.Immunofluorescence staining showed that,after Nurr1knockdown,the number of CD74-immunoreactive cells in mouse brain tissue was markedly increased.In addition,Cd74 expression was increased in a mouse model of Parkinson’s disease induced by treatment with 6-hydroxydopamine.Ta ken togethe r,our res ults suggest that Nurr1 deficiency results in an increase in Cd74 expression,thereby leading to the destruction of dopaminergic neuro ns.These findings provide a potential therapeutic target for the treatment of Parkinson’s disease.

电针结合天麻素对PD模型大鼠黑质TH、TNF-α表达的影响

目的观察电针结合天麻素对帕金森病(PD)大鼠黑质酪氨酸羟化酶(TH)和肿瘤坏死因子-α(TNF-α)表达的影响,探讨电针结合天麻素对PD的保护机制。方法将50只SD大鼠随机分为正常组、模型组、电针组、天麻素组和电针结合天麻素组,每组10只。PD动物模型采用颈背部皮下注射鱼藤酮来造模,天麻素组给予天麻素腹腔注射;电针组给予高频电针治疗;电针结合天麻素组先天麻素腹腔注射,再电针治疗;三组均治疗21 d。采用免疫组织化学法和Western Blot检测黑质TH和TNF-α的表达。结果与正常组相比,模型组大鼠黑质TH表达减少(P<0.01),天麻素、电针和电针结合天麻素治疗后TH表达增加(P<0.01);与天麻素组和电针组相比,电针结合天麻素组TH表达增加(P<0.05)。与正常组相比,模型组大鼠黑质TNF-α表达增加(P<0.01),天麻素、电针和电针结合天麻素治疗后黑质TNF-α表达减少(P<0.01),与天麻素组和电针组相比,电针结合天麻素组TNF-α表达减少(P<0.05)。结论电针结合天麻素可上调PD大鼠黑质TH表达,下调TNF-α表达,且作用强于天麻素或电针。

Effect of Bushen Huoxue Decoction(补肾活血饮) on the Orphan Receptor and Tyrosine Hydroxylase in the Brain of Rats with Parkinson's Disease

Objective：To explore the effect of Bushen Huoxue Decoction（补肾活血饮,BHD） on the orphan receptor（Nurr1） and tyrosine hydroxylase（TH） in the brain of rats with Parkinson＇s disease（PD）.Methods：One hundred and twenty SD rats were divided into 100 in the model group and 20 in the normal control group,fifty-eight SD rats from the model group,established into PD model successfully by injuring their substantia nigra （SSN） with 6-hydroxydopamine,were divided equally into the model group and the test group,and they were treated with saline and BHD,respectively,for eight successive weeks.The change in the rats＇ behavior before and after treatment was observed by counting the cycles of rotation induced by apomorphine injection; the pathology of neurons,level of Nurr1 mRNA expression,and amount of TH positive cells in SSN were observed after treatment.Results：The rats＇ behavior was improved in the tested group significantly,the rotation cycle after treatment being 84.0±20.0 cycles/40 min,which was significantly lower than that in the model group（377.0±62.3 cycles/40 min,P〈0.01）.Besides,the Nurr1 mRNA expression and TH positive cell in the test group were 0.97±0.15 and 49.40±14.72,respectively,which were significantly higher than those in the model group,0.22±0.03 and 5.45±2.58,respectively（all P〈0.01）.Conclusion：BHD could treat PD by enhancing the Nurr1 mRNA expression,increasing the TH content in brain,and promoting the repairing of injured neuron in cerebral SSN.

外周血酪氨酸羟化酶含量与首发抑郁症的相关性研究

目的探讨外周血酪氨酸羟化酶(TH)含量与首发抑郁症的相关性,为阐明抑郁症的临床诊断及发病机制提供科学依据。方法选取2021年7月至2022年9月在我院就诊的40例首发抑郁症患者为病例组,另选取在我院体检中心进行健康体检的46名健康者为对照组。两组研究对象均进行汉密尔顿焦虑量表(HAMA)和汉密尔顿抑郁量表(HAMD)评分,并采集外周血测定TH含量。比较两组的TH含量及在不同性别和不同年龄段中的含量;通过偏相关分析TH含量与HAMA、HAMD评分的相关性;通过受试者工作特征曲线(ROC)的曲线下面积(AUC)来评价TH对抑郁症的诊断价值。结果病例组的TH含量显著低于对照组(P<0.05)。病例组的HAMA、HAMD评分与TH含量呈负相关(P<0.05)。ROC曲线分析显示,TH预测抑郁症的AUC为0.660。结论外周血TH含量降低可能与首发抑郁症的发生和发展有关,可作为抑郁症的生物学标志,对预测抑郁症具有一定的临床价值。

Quanti?cation of Tyrosine Hydroxylase and Erb B4 in the Locus Coeruleus of Mood Disorder Patients Using a Multispectral Method to Prevent Interference with Immunocytochemical Signals by Neuromelanin

The locus coeruleus(LC) has been studied in major depressive disorder(MDD) and bipolar disorder(BD). A major problem of immunocytochemical studies in the human LC is interference with the staining of the immunocytochemical end-product by the omnipresent natural brown pigment neuromelanin. Here, we used a multispectral method to untangle the two colors: blue immunocytochemical staining and brown neuromelanin.We found significantly increased tyrosine hydroxylase(TH) in the LC of MDD patients—thus validating the method—but not in BD patients, and we did not find significant changes in the receptor tyrosine-protein kinase ErbB4 in the LC in MDD or BD patients. We observed clear co-localization of ErbB4, TH, and neuromelanin in the LC neurons. The different stress-related molecular changes in the LC may contribute to the different clinical symptoms in MDD and BD.

CRISPR/Cas9-mediated Tyrosine hydroxylase knockout resulting in larval lethality in Agrotis ipsilon

Tyrosine hydroxylase (TH)is involved in insect melanin and the catecholamine biosynthesis pathway.TH as an enzyme catalyzing the conversion of tyrosine to 3,4- dihydroxyphenylalanine is the first step reaction in the pathway.Although TH has been proven to affect the pigmentation of the epidermis and development in many insects,there is no report about physiological function of the THgene inAgrotis ipsilon.Here we cloned the TH gene from A.ipsilon.Semi-quantitative real-time polymerase chain reaction (PCR) analysis showed that AiTH was expressed at all development stages.Moreover,its high expression levels in the head and epidermis suggest that it is mainly related to pigment deposition and insect development.Then,we used the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9system to target the AiTH gene:deletion events were detected at the target sites.Compared with the control group,a few mutants with the phenomenon of narrowing in the egg shell and embryos can develop but cannot hatch;the other hatched embryos were seriously dehydrated after hatching and died within the first day.Quantitative real-time PCR analysis revealed that THwas down-regulated inAiTHmutants.Here,our work demonstrated thatAiTHplays an important role in growth and development of newly hatched larvae;meanwhile,it would be a promising target to explore a control strategy for A.ipsilon.

蛋白酶体抑制剂MG132对慢性缺氧致小鼠记忆损伤的作用及其机制

目的探讨蛋白酶体抑制剂MG132对慢性缺氧所致小鼠记忆功能损伤的作用及其机制。方法(1)利用低氧工作站构建小鼠中脑多巴胺能神经元MN9D细胞缺氧损伤模型。将MN9D细胞分为常氧组及缺氧12 h、24 h和48 h组,观察缺氧对MN9D细胞中酪氨酸羟化酶(TH)、泛素的K48链(Ub-K48)和Ub-K63表达的影响;将MN9D细胞分为常氧组、缺氧组、缺氧+MG132(25、50、100、200)μmol/L组,观察MG132对缺氧细胞中上述蛋白表达的影响。(2)利用低压舱建立低压缺氧小鼠记忆功能损伤模型。将C57小鼠随机分为常氧组、缺氧3 d组、缺氧21 d组,每组10只,观察低压低氧对小鼠中脑黑质致密部(SNc)TH、Ub-K48和Ub-K63表达的影响;将小鼠随机分为常氧组、缺氧21 d组、缺氧21 d+MG132组,每组8只,观察MG132对缺氧所致小鼠空间记忆损伤的影响。(3)采用Western blotting检测不同缺氧时长及MG132预处理再低氧处理的MN9D细胞中TH、Ub-K48和Ub-K63的蛋白表达水平;采用新物体识别测试检测各组小鼠记忆功能,免疫荧光染色检测SNc区TH阳性免疫反应面积百分比,Western blotting检测小鼠SNc区TH、Ub-K48和Ub-K63表达水平。结果(1)与常氧组比较,缺氧24 h组MN9D细胞中Ub-K48和Ub-K63表达水平增高(P<0.05),TH表达水平降低(P<0.05);各缺氧组Ub-K48/TH和Ub-K63/TH表达水平均增高(P<0.05)。与缺氧组比较,缺氧+MG132100μmol/L组和缺氧+MG132200μmol/L组MN9D细胞中Ub-K48/TH和Ub-K63/TH表达水平降低(P<0.05)。(2)与常氧组比较,缺氧3 d组和缺氧21 d组小鼠中脑SNc区TH表达水平降低(P<0.001),Ub-K48/TH和Ub-K63/TH表达水平升高(P<0.05);缺氧21 d组小鼠新物体识别指数降低(P<0.01),SNc区多巴胺能神经元TH阳性免疫反应面积百分比降低(P<0.05)。与缺氧21 d组比较,缺氧21 d+MG132组小鼠新物体识别指数升高(P<0.01)。结论蛋白酶体抑制剂MG132可改善慢性缺氧所致小鼠记忆损伤,其机制可能与抑制Ub-K48和Ub-K63,上调多巴胺能神经元TH表达有关。