Are TrkB receptor agonists the right tool to fulfill the promises for a therapeutic value of the brain-derived neurotrophic factor?

Brain-derived neurotrophic factor signaling via its receptor tro pomyosin receptor kinase B regulates several crucial physiological processes.It has been shown to act in the brain,promoting neuronal survival,growth,and plasticity as well as in the rest of the body where it is involved in regulating for instance aspects of the metabolism.Due to its crucial and very pleiotro pic activity,reduction of brain-derived neurotrophic factor levels and alterations in the brain-derived neurotrophic factor/tropomyosin receptor kinase B signaling have been found to be associated with a wide spectrum of neurological diseases.Howeve r,because of its poor bioavailability and pharmacological properties,brain-derived neurotrophic factor itself has a very low therapeutic value.Moreover,the concomitant binding of exogenous brain-derived neurotrophic factor to the p75 neurotrophin receptor has the potential to elicit several unwanted and deleterious side effects.Therefo re,developing tools and approaches to specifically promote tropomyosin receptor kinase B signaling has become an important goal of translational research.Among the newly developed tools are different categories of tropomyosin receptor kinase B receptor agonist molecules.In this review,we give a comprehensive description of the diffe rent tro pomyosin receptor kinase B receptor agonist drugs developed so far and of the res ults of their application in animal models of several neurological diseases.Moreover,we discuss the main benefits of tropomyosin receptor kinase B receptor agonists,concentrating especially on the new tropomyosin receptor kinase B agonist antibodies.The benefits observed both in vitro and in vivo upon application of tropomyosin receptor kinase B receptor agonist drugs seem to predominantly depend on their general neuroprotective activity and their ability to promote neuronal plasticity.Moreover,tro pomyosin receptor kinase B agonist antibodies have been shown to specifically bind the tropomyosin receptor kinase B receptor and not p75 neurotrophin receptor.Therefore,while,based on the current knowledge,the tropomyosin receptor kinase B receptor agonists do not seem to have the potential to reve rse the disease pathology per se,promoting brainderived neurotrophic factor/tro pomyosin receptor kinase B signaling still has a very high therapeutic relevance.

Effects of ginsenoside on brain-derived neurotrophic factor and tyrosine kinase B mRNA expression in the hippocampal formation of aged rats

BACKGROUND： There are a limited number of studies involving the effects of ginsenosides, the active component of ginseng, on expression of hippocampal TrkB mRNA in aged rats. OBJECTIVE： To observe expression of brain-derived neurotrophic factor （BDNF） and tyrosine kinase B （TrkB） mRNA in the hippocampal formation of aged rats, as well as changes after ginsenoside administrated. DESIGN, TIME AND SETTING： A randomized, controlled experiment was performed at the Department of Anatomy, College of Basic Medical Sciences, China Medical University in March 2005. MATERIALS： A total of 39 female, Wistar rats were randomly divided into 3 groups （n = 13 each）： young （3-5 months old）, aged （27 months old）, and ginsenoside group （received 25mg/kg/d ginsenoside in the drinking water between 17 and 27 months of age）. METHODS： Following anesthesia, the rats were exsanguinated and perfused transcardially with chilled, heparinized, 0.9% saline. The brains were removed and post-fixed in 40 g/L paraformaldehyde/phosphate buffer for 20 minutes, and further incubated in 30% sucrose/phosphate buffer overnight. MAIN OUTCOME MEASURES： In situ hybridization, immunohistochemistry, and image analysis were used to investigate expression of BDNF and TrkB mRNA in the hippocampal formation. RESULTS： The expression levels of BDNF in the hippocampal CA3 and CA1 of aged rats was significantly less than the young group （t = 2.879, 1.814, 1.984, P 〈 0.05）. BDNF expression was significantly greater in the dentate gyrus of the ginsenoside group, compared with the aging group （t = 1.943, P 〈 0.01）. The expression of TrkB mRNA in the hippocampal CA3, CA1, and dentate gyrus of aged rats was less than the young group （t = 3.540, 3.629, 17.905, P 〈 0.01）. TrkB mRNA expression in the CA3 region and dentate gyrus of the ginsenoside group was significantly greater compared with the aging group （t = 1.293, 3.386, P 〈 0.05, 0.01 ）. CONCLUSION： BDNF and TrkB mRNA expression in the hippocampal formation were reduced in the aged group. However, ginsenosides can increase BDNF and TrkB mRNA expression in the hippocampal formation.

Auditory deprivation modifies the expression of brain-derived neurotrophic factor and tropomyosin receptor kinase B in the rat auditory cortex

The development and plasticity of central auditory system can be influenced by the change of peripheral neuronal activity. However, the molecular mechanism participating in the process remains elusive. Brain-derived neurotrophic factor(BDNF) binding with its functional receptor tropomyosin receptor kinase B(TrkB) has multiple effects on neurons. Here we used a rat model of auditory deprivation by bilateral cochlear ablation, to investigate the changes in expression of BDNF and Trk B in the auditory cortex after auditory deprivation that occurred during the critical period for the development of central auditory system. Reverse transcription-quantitative polymerase chain reaction(RTqPCR) and immunohistochemistry methods were adopted to detect the m RNA and protein expression levels of BDNF and TrkB in the auditory cortex at 2, 4, 6 and 8 weeks after surgery, respectively. The change in the expression of BDNF and TrkB mRNAs and proteins followed similar trend. In the bilateral cochlear ablation groups, the BDNF-TrkB expression level initially decreased at 2 weeks but increased at 4 weeks followed by the reduction at 6 and 8 weeks after cochlear removal, as compared to the age-matched sham control groups. In conclusion, the BDNF-TrkB signaling is involved in the plasticity of auditory cortex in an activity-dependent manner.

Neuroprotective effects of exogenous brain-derived neurotrophic factor on amyloid-beta 1-40-induced retinal degeneration

Amyloid-beta(Aβ)-related alterations,similar to those found in the brains of patients with Alzheimer's disease,have been observed in the retina of patients with glaucoma.Decreased levels of brain-derived neurotrophic factor(BDNF)are believed to be associated with the neurotoxic effects of Aβpeptide.To investigate the mechanism underlying the neuroprotective effects of BDNF on Aβ_(1-40)-induced retinal injury in Sprague-Dawley rats,we treated rats by intravitreal administration of phosphate-buffered saline(control),Aβ_(1-40)(5 nM),or Aβ_(1-40)(5 nM)combined with BDNF(1μg/mL).We found that intravitreal administration of Aβ_(1-40)induced retinal ganglion cell apoptosis.Fluoro-Gold staining showed a significantly lower number of retinal ganglion cells in the Aβ_(1-40)group than in the control and BDNF groups.In the Aβ_(1-40)group,low number of RGCs was associated with increased caspase-3 expression and reduced TrkB and ERK1/2 expression.BDNF abolished Aβ_(1-40)-induced increase in the expression of caspase-3 at the gene and protein levels in the retina and upregulated TrkB and ERK1/2 expression.These findings suggest that treatment with BDNF prevents RGC apoptosis induced by Aβ_(1-40)by activating the BDNF-TrkB signaling pathway in rats.

Tropomyosin-related kinase B/brain derived-neurotrophicfactor signaling pathway as a potential therapeutic targetfor colorectal cancer

Colorectal cancer(CRC) is the second most common cause of cancer-related death in western countries. Approximately one-quarter of newly diagnosed patients for CRC have metastases, and a further 40%-50% experience disease recurrence or develop metastases after all standard therapies. Therefore, understanding the molecular mechanisms involved in the progression of CRC and subsequently developing novel therapeutic targets is crucial to improve management of CRC and patients' long-term survival. Several tyrosine kinase receptors have been implicated in CRC development, progression and metastasis, including epidermal growth factor receptor(EGFR) and vascular EGFR. Recently, tropomyosin-related kinase B(Trk B), a tyrosine kinase receptor, has been reported in CRC and found to clearly exert several biological and clinical features, such as tumor cell growth and survival in vitro and in vivo, metastasis formation and poor prognosis. Here we review the significance of Trk B and its ligand brain derived-neurotrophic factor in CRC. We focus on their expression in CRC tumor samples, and their functional roles in CRC cell lines and in in vivo models. Finally we discuss therapeutic approaches that can lead to the development of novel therapeutic agents for treating Trk B-expressing CRC tumors.

Therapeutic potential of brain-derived neurotrophic factor(BDNF)and a small molecular mimics of BDNF for traumatic brain injury

Traumatic brain injury（TBI） is a major health problem worldwide.Following primary mechanical insults,a cascade of secondary injuries often leads to further neural tissue loss.Thus far there is no cure to rescue the damaged neural tissue.Current therapeutic strategies primarily target the secondary injuries focusing on neuroprotection and neuroregeneration.The neurotrophin brain-derived neurotrophic factor（BDNF） has significant effect in both aspects,promoting neuronal survival,synaptic plasticity and neurogenesis.Recently,the flavonoid 7,8-dihydroxyflavone（7,8-DHF）,a small Trk B agonist that mimics BDNF function,has shown similar effects as BDNF in promoting neuronal survival and regeneration following TBI.Compared to BDNF,7,8-DHF has a longer half-life and much smaller molecular size,capable of penetrating the blood-brain barrier,which makes it possible for non-invasive clinical application.In this review,we summarize functions of the BDNF/Trk B signaling pathway and studies examining the potential of BDNF and 7,8-DHF as a therapy for TBI.

Brain-derived neurotrophic factor prevents beta-amyloid-induced apoptosis of pheochromocytoma cells by regulating Bax/Bcl-2 expression

Brain-derived neurotrophic factor was utilized in the present study to treat cell injury models induced by aggregated β-amyloid（25 35）. Methylthiazolyldiphenyl-tetrazolium bromide assay and western blot analysis showed that brain-derived neurotrophic factor provided neuroprotection against cellular apoptosis by suppressing the decline in β-amyloid（25 35）-induced cell activity and the increasing ratio of Bax/Bcl-2. After treating pheochromocytoma cells with tyrosine kinase receptor B receptor inhibitor K252a, brain-derived neurotrophic factor reverses the above- mentioned changes. The experimental findings suggested that brain-derived neurotrophic factor prevented β-amyloid peptide-induced cellular apoptosis by modulating Bax/Bcl-2 expression, and this effect was associated with binding to the specific tyrosine kinase receptor B receptor.

TrkB and p-trkB expression in brain-derived neurotrophic factor-pretreated rat retina following acute high intraocular pressure

BACKGROUND： Exogenous brain-derived neurotrophic factor （BDNF） promotes retinal ganglion cell survival. However, the protective mechanisms remain unclear. OBJECTIVE： To investigate changes in retinal tyrosine kinase receptor B （trkB） expression and effects of exogenous BDNF on trkB activation in a rat model of acute high intraocular pressure （HtOP）. DESIGN, TIME AND SETTING： A randomized, controlled, animal experiment was performed at the Department of Anatomy and Neurobiology, Xiangya Medical School, Central South University from January 2004 to August 2006. MATERIALS： Rabbit anti-BDNF and anti-trkB.FL（full-length） polyclonal antibodies were purchased from Santa Cruz Biotechnology, USA; rabbit anti-p-trkB polyclonal antibodies were purchased from Cellsignal, USA. METHODS： A total of 48 healthy, adult, Sprague Dawiey rats were randomly assigned to acute HIOP （without BDNF pre-treatment） and BDNF pre-treated groups, with 24 animals in each group. In the BDNF pre-treated group, the left eyes were intravitreally injected with 3 pg/kg BDNF 2 days prior to HIOP. Rats in the acute HIOP group were not pre-treated with BDNE HIOP models were established by increased intraocular pressure in the left eyes until the b-wave of flash electroretinogragh disappeared and pressure was maintained for 60 minutes. The right eyes of all rats were not treated and served as the normal controls. MAIN OUTCOME MEASURES： Retinal structure and cell numbers in the ganglion cell layer （GCL） were detected by Nissl staining; expression of trkB and phosphorylated trkB in the rat retina were determined by immunohistochemistry. RESULTS： A greater number of GCL neurons were observed in the pre-treated group compared to the acute HIOP group （P 〈 0.05）. TrkB expression was significantly increased following HIOP at days 1 and 3 （P 〈 0.05）, but expression varied between retinal areas. Although trkB expression decreased at 7 days, phosphorylated trkB dramatically decreased with increasing time （P 〈 0.05）. TrkB expression in BDNF pre-treated rats was similar to the acute HIOP group at early injury time points. Nevertheless, trkB expression was significantly decreased compared to the acute HIOP group at 7 days （P 〈 0.05）, and phosphorylated trkB expression was significantly greater compared to the acute HIOP group at each time point （P〈 0.05）. CONCLUSION： TrkB expression displayed temporal and spatial changes in the rat retina following acute HIOP, and trkB up-regulation suggested that more BDNF was required for treating the injured retina. Exogenous BDNF partially ameliorated decreased expression of phosphorylated trkB and provided protection to the injured retina, to a certain degree, following HIOP.

Levetiracetam induces tyrosine kinase receptor B expression in SH-SY5Y cells

Tyrosine kinase receptor B （TrkB） plays an important role in long-term potentiation and memory formation.The present study used all-trans retinoic acid to induce TrkB expression in SH-SY5Y cells,and observed the effects of levetiracetam （LEV） on TrkB expression.Following exposure to 10,50,and 100 μg/mL LEV,the number of TrkB-positive cells,and average absorbance value were increased.Results demonstrated that LEV can induce TrkB expression in SH-SY5Y cells.

Express=on of Brain-derived Neurotrophic Factor and Tyrosine Kinase B in Cerebellum of Poststroke Depression Rat Model

Background： The pathophysiology of poststroke depression （PSD） remains elusive because of its proposed multifactorial nature. Accumulating evidence suggests that brain-derived neurotrophic factor （BDNF） plays a key role in the pathophysiology of depression and PSD. And the cerebellar dysfunction may be important in the etiology of depression; it is not clear whether it also has a major effect on the risk of PSD. This study aimed to explore the expression of BDNF and high-affinity receptors tyrosine kinase B （TrkB） in the cerebellum of rats with PSD. Methods： The rat models with focal cerebral ischemic were made using a thread embolization method. PSD rat models were established with comprehensive separate breeding and unpredicted chronic mild stress （UCMS） on this basis. A normal control group, depression group, and a stroke group were used to compare with the PSD group. Thirteen rats were used in each group. Immunohistochemistry and reverse transcription-polymerase chain reaction （RT-PCR） for detecting the expression of BDNF and TrkB protein and mRNA in the cerebellum were used at the 29th day following the UCMS. Results： Compared with the normal control group and the stroke group, the number of BDNF immunoreactive （IR） positive neurons was less in the PSD group （P 〈 0.05）. Furthermore, the number ofTrkB 1R positive cells was significantly less in the PSD group than that in the normal control group （P 〈 0.05）. The gene expression of BDNF and TrkB in the cerebellum of PSD rats also decreased compared to the normal control group （P 〈 0.05）. Conclusions： These findings suggested a possible association between expression of BDNF and TrkB in the cerebellum and the pathogeuesis of PSD.

基于BDNF/TrkB/CREB通路研究六味地黄丸对丙戊酸钠诱导的孤独症谱系障碍模型仔鼠的作用机制

目的基于脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)/酪氨酸激酶受体B(tyrosine kinase receptor B,TrkB)/cAMP反应元件结合蛋白(cAMP response element binding protein,CREB)通路,探讨六味地黄丸对丙戊酸钠(sodium valproate,VPA)诱导的孤独症谱系障碍(autism spectrum disorder,ASD)仔鼠的作用机制。方法将13只SD孕鼠随机分为两组,其中10只孕鼠在第12.5天时腹腔注射VPA溶液(600 mg·kg^(-1))为VPA组,另外3只孕鼠注射等体积生理盐水为对照组。第21天对两组雄性仔鼠开展行为学检测,筛选出符合ASD疾病模型的仔鼠30只,随机分为模型组(等体积生理盐水),维生素D组(1480 IU·kg^(-1)),六味地黄丸高(3 g·kg^(-1))、中(1.5 g·kg^(-1))、低(0.75 g·kg^(-1))剂量组,每组6只。正常雄性仔鼠6只,设为空白组(等体积生理盐水)。各组仔鼠连续灌胃14 d,1次/d,给药后再次开展行为学检测。尼氏染色观察各组仔鼠海马组织神经元形态学变化,比色法检测各组仔鼠海马组织中谷氨酸(glutamic acid,GLU)、γ-氨基丁酸(gamma-aminobutyric acid,GABA)含量;qRT-PCR检测各组仔鼠海马组织中BDNF、TrkB、CREB mRNA相对表达。结果与对照组比较,VPA组仔鼠体质量、身长、尾长更小(P<0.05)。与空白组比较,模型组社交障碍症状明显(P<0.01),焦虑障碍症状明显(P<0.01),重复刻板行为增多(P<0.05或P<0.01),海马神经元结构损伤,GLU升高(P<0.01)、GABA下降(P<0.01),BDNF、TrkB、CREB mRNA表达降低(P<0.05或P<0.01);与模型组比较,维生素D组及六味地黄丸中、低剂量组仔鼠社交能力增强(P<0.05或P<0.01),焦虑障碍减轻(P<0.05或P<0.01),重复刻板行为减少(P<0.01或P<0.05),海马神经元结构明显复原,GLU下降(P<0.01),BDNF、TrkB、CREB mRNA表达增加(P<0.05或P<0.01),六味地黄丸中、低剂量组GABA上升(P<0.05或P<0.01)。结论六味地黄丸能显著改善VPA诱导的ASD仔鼠行为表现,增强海马组织神经元的再生与修复,其机制可能与平衡GLU、GABA水平,上调仔鼠海马组织中BDNF/TrkB/CREB的表达有关。

卡马西平对三叉神经痛大鼠三叉神经节及血清中BDNF表达变化的影响

目的:三叉神经痛(trigeminal neuralgia,TN)是一种严重的慢性神经病理性疼痛,主要影响三叉神经分布区域,临床治疗效果不佳。TN的治疗方法众多,但目前临床上主要是通过服用卡马西平(carbamazepine,CBZ)来抑制疼痛。脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)和慢性痛密切相关。本研究通过慢性压迫性损伤眶下神经(chronic constriction injury of the infraorbital nerve,ION-CCI)大鼠模型观察CBZ处理对TN大鼠三叉神经节(trigeminal ganglion,TG)和血清中BDNF表达的影响。方法:建立雄性SD大鼠ION-CCI模型,并将其随机分为假手术(sham)组、TN组、TN+低剂量(20 mg/kg)CBZ处理组、TN+中剂量(40 mg/kg)CBZ处理组、TN+高剂量(80 mg/kg)CBZ处理组。在手术前后定时测量各组大鼠的面部机械痛阈(mechanical pain threshold)。使用实时聚合酶链反应技术测定各组大鼠TG中BDNF及酪氨酸激酶受体B(tyrosine kinase receptor B,TrkB)的mRNA含量,免疫荧光技术观察各组大鼠TG中BDNF蛋白质在神经元上的表达情况,蛋白质印迹法检测各组大鼠TG中BDNF、TrkB、细胞外调节蛋白激酶(extracellular regulated protein kinases,ERK)及磷酸化的细胞外调节蛋白激酶(phospho-extracellular regulated protein kinases,p-ERK)的蛋白质表达变化,酶联免疫吸附试验(enzyme-linked immunosorbent assay,ELISA)检测各组大鼠血清中BDNF的表达变化。结果:行为学检测结果表明:手术前,各组大鼠右侧面部感觉区域的机械痛阈差异均无统计学意义(均P>0.05);术后第3天开始,TN组大鼠机械痛阈与sham组相比均明显降低(均P<0.01),TN+80 mg/kg CBZ处理组、TN+40 mg/kg CBZ处理组和TN+20 mg/kg CBZ处理组与TN组相比均升高(均P<0.05)。实时聚合酶链反应和蛋白质印迹法结果显示:TN组大鼠TG中的BDNF、TrkB的mRNA及蛋白质表达量均较sham组升高(均P<0.05),TN+20 mg/kg CBZ处理组、TN+40 mg/kg CBZ处理组、TN+80 mg/kg CBZ处理组均较TN组降低(均P<0.05);与TN组相比,TN+20 mg/kg CBZ处理组、TN+40 mg/kg CBZ处理组、TN+80 mg/kg CBZ处理组大鼠TG中的p-ERK水平均显著降低(均P<0.05)。免疫荧光双标结果表明:TN组TG中的BDNF和神经元特异性核蛋白(neuron-specific nuclear protein,NeuN)主要共表达在神经元上,与sham组比较BDNF和NeuN水平升高(P<0.05),TN+20 mg/kg CBZ处理组、TN+40 mg/kg CBZ处理组、TN+80 mg/kg CBZ处理组与TN组大鼠比较二者表达均降低(均P<0.05)。ELISA检测结果显示:TN组大鼠血清中BDNF的水平较sham组显著升高(P<0.05),TN+20 mg/kg CBZ处理组、TN+40 mg/kg CBZ处理组、TN+80 mg/kg CBZ处理组均较TN组大鼠降低(均P<0.05)。Spearman相关分析显示血清中BDNF水平与机械痛阈呈负相关(r=−0.650,P<0.01)。结论:CBZ处理可以抑制TN大鼠TG中BDNF及其受体TrkB的表达,降低TN大鼠血清中BDNF水平及ERK信号通路磷酸化水平,进而抑制TN。可以考虑将血清中BDNF水平作为诊断TN和评估预后的指标。

针灸通过阻断BDNF/TrkB信号通路改善肠易激综合征大鼠的肠道屏障功能和内脏疼痛

目的:探究针灸是否通过调节脑源性神经营养因子(BDNF)及其下游酪氨酸激酶受体B(TrkB)对肠易激综合征(IBS)大鼠的肠道屏障和内脏疼痛产生影响,探究BDNF/TrkB信号通路作为针灸治疗新靶点的可能性。方法:将60只SD大鼠随机分为健康组、IBS组、针灸组、阳性对照组、针灸+TrkB激活组,每组12只。建立IBS大鼠模型,腹部撤回反射(AWR)检测各组大鼠内脏疼痛;检测各组大鼠结肠TNF-α、IL-1β水平;免疫组化检测结肠黏膜胞质紧密黏连蛋白1(ZO-1)、闭合蛋白(occludin)表达水平;荧光定量PCR及Western blot检测各组大鼠结肠BDNF、TrkB mRNA及蛋白表达水平。结果:与健康组相比,IBS组大鼠结肠黏膜出现破损,ZO-1、occludin表达显著降低,大鼠AWR评分、粪便含水量、TNF-α、IL-1β含量、结肠BDNF、TrkB mRNA及BDNF蛋白表达量、TrkB磷酸化程度显著升高(P<0.05);与IBS组相比,针灸组、阳性对照组大鼠结肠黏膜逐渐恢复,ZO-1、occludin表达显著升高,大鼠AWR评分、粪便含水量、TNF-α、IL-1β含量、结肠BDNF、TrkB mRNA及BDNF蛋白表达量、TrkB磷酸化程度显著降低(P<0.05);与针灸组相比,针灸+TrkB激活组大鼠结肠黏膜仍有病变,ZO-1、occludin表达显著降低,大鼠AWR评分、粪便含水量、TNF-α、IL-1β含量、结肠BDNF、TrkB mRNA及BDNF蛋白表达量、TrkB磷酸化程度显著升高(P<0.05)。结论:针灸可通过调控BDNF/TrkB通路,抑制相关蛋白表达,改善肠道屏障功能,减轻内脏疼痛及炎症反应,缓解IBS。

腧穴“解郁方”对慢性不可预测轻度应激抑郁大鼠下丘脑-垂体-肾上腺轴及BDNF/TrkB/CREB通路的影响

目的:观察腧穴“解郁方”对慢性不可预测轻度应激(CUMS)抑郁大鼠下丘脑-垂体-肾上腺(HPA)轴和脑源性神经营养因子(BDNF)/酪氨酸激酶B受体(TrkB)/环磷酸腺苷反应元件结合蛋白(CREB)信号通路的影响。方法:40只无特定病原体(SPF)级Sprague Danley(SD)雄性大鼠随机分为空白组(10只)、模型组(10只)、西药组(10只)、针刺组(10只),除空白组外,其余3组连续28 d构建CUMS抑郁大鼠模型,造模成功后,西药组连续14 d灌胃盐酸帕罗西汀混悬液,每日1次;针刺组针刺百会、太冲、神门,每日1次,每次20 min,连续针刺14 d。苏木素-伊红(HE)染色观察大鼠海马病理变化,酶联免疫吸附法(ELISA)测定血清促肾上腺皮质激素释放激素(CRH)、促肾上腺皮质激素(ACTH)、皮质醇(CORT)水平;免疫组化(IHC)检测海马BDNF、TrkB表达情况,蛋白质免疫印迹法(Western Blot)及实时荧光定量-聚合酶链式反应(PCR)测定海马BDNF、TrkB、CREB蛋白及mRNA的表达。结果:与空白组比较,模型组血清CRH、ACTH和CORT含量上升(P<0.01),海马病理损伤严重,海马BDNF、TrkB平均光密度降低(P<0.01),BDNF、TrkB、CREB蛋白及mRNA明显下降(P<0.05或P<0.01)。与模型组比较,针刺组血清CRH、ACTH、CORT含量下降(P<0.05),海马病理损害明显减轻,BDNF、TrkB平均光密度明显增加(P<0.05),BDNF、CREB、TrkB蛋白及mRNA表达水平上升(P<0.05)。结论:腧穴“解郁方”可能通过调节HPA轴和调控BDNF/TrkB/CREB信号通路,改善CUMS诱导的大鼠抑郁样行为。

柴胡加龙骨牡蛎汤对肿瘤后抑郁模型大鼠海马BDNF/TrkB/CREB信号通路的影响

目的探讨柴胡加龙骨牡蛎汤(CLM)对肿瘤后抑郁模型大鼠海马脑源性神经营养因子/酪氨酸激酶受体B/环磷酸腺苷反应元件结合蛋白(BDNF/TrkB/CREB)信号通路的影响。方法采用接种腹水癌细胞系S180细胞建立肿瘤大鼠模型,再通过慢性不可预知温和刺激(CUMS)诱导肿瘤后抑郁大鼠模型。将12只模型大鼠分为模型对照组、CLM组(每10 g体质量给药0.1 mL),各6只;另设正常对照组(6只)。采用旷场实验(OFT)、悬尾实验(TST)、强迫游泳实验(FST)检测大鼠的抑郁样行为,酶联免疫吸附试验(ELISA)试剂盒检测大鼠血清超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)水平,以及海马组织白细胞介素(IL)-1β、肿瘤坏死因子-α(TNF-α)与IL-10的水平,免疫印迹(Western blot)法检测BDNF,TrkB,CREB及磷酸化环腺苷酸应答元件结合蛋白(p-CREB)的水平。结果与模型对照组比较,CLM组大鼠OFT距离、时间及TST,FST静止时间均显著减少(P<0.01),血清SOD和GSH-Px水平均显著升高(P<0.01),海马组织中IL-1β和TNF-α水平均显著升高(P<0.01),IL-10水平显著降低(P<0.01),BDNF和TrkB蛋白表达及p-CREB/CREB均显著上调(P<0.01)。结论CLM可显著改善肿瘤后抑郁模型大鼠的抑郁样行为,抑制海马神经炎性反应,可能与上调BDNF/TrkB/CREB信号通路有关。

BDNF/TrKB介导的突触丢失对创伤性脑损伤小鼠远期认知障碍的影响及机制

目的探究脑源性神经营养因子(BDNF)/酪氨酸激酶受体(TrK)B介导的突触丢失对创伤性脑损伤(TBI)小鼠远期认知障碍的影响及机制。方法采用改良的Allen重锤打击法制作TBI模型,将小鼠分为Sham组、TBI组、TBI_OE_NC组、TBI_OE_BDNF组、TBI_Sh_NC组、TBI_Sh_BDNF组,每组40只。Sham组、TBI组分别在造模后1、3、5、7 d检测神经元突触后致密物厚度和突触体密度、BDNF、TrkB mRNA及蛋白表达。将OE_NC和OE_BDNF组腺病毒载体3μl注入承受单侧大脑皮质重锤打击的小鼠海马体,免疫荧光法检测BDNF、突触素(Synaptophysin)在小鼠海马体中的表达,Western印迹检测TrkB、p-TrkB、突触蛋白(SYN)1、SYNA、突触后致密蛋白(PSD)95等蛋白表达水平,Morris水迷宫实验检测小鼠定位航行和空间探索能力。将TBI_Sh_NC和TBI_Sh_BDNF组腺病毒载体3μl注入正常小鼠海马体,免疫荧光法检测Synaptophysin在海马体中的表达,Morris水迷宫实验检测定位航行和空间探索能力。TUNEL法检测Sham、OE_NC和OE_BDNF组脑组织细胞凋亡水平,Western印迹检测磷脂酰激酶-3激酶(PI3K)、蛋白激酶B(AKT)、p-PI3K、p-AKT、B细胞淋巴瘤(Bcl)-2、Bcl-2相关X蛋白(Bax)、cleaved-半胱天冬蛋白酶(caspased)3等蛋白水平。结果与Sham组比较,TBI组脑海马体神经元突触后致密物厚度(5、7 d)和突触体密度(3、5、7 d)显著降低(P<0.05)。TBI组BDNF、TrkB mRNA和蛋白水平随时间逐渐降低(P<0.05)。相较于TBI_OE_NC组,TBI_OE_BDNF组脑海马体中BDNF、TrkB、p-TrkB、SYN1、SYNA、PSD95表达提高,细胞凋亡水平降低,p-PI3K、p-AKT、Bcl-2蛋白表达增加,Bax、cleaved-caspased3蛋白表达减少,差异有统计学意义(P<0.05)。结论TBI诱导BDNF-TrkB表达减少,进而抑制PI3K/Akt通路开启细胞凋亡途径,导致突触数量减少,损伤小鼠的远期认知能力。

奥氮平介导环磷酸腺苷反应元件结合蛋白/脑源性神经营养因子/酪氨酸蛋白激酶受体B通路对精神分裂模型大鼠的神经修复作用

目的 探讨奥氮平通过对环磷酸腺苷反应元件结合蛋白(CREB)/脑源性神经营养因子(BDNF)/酪氨酸蛋白激酶受体B(TrkB)通路的影响对精神分裂模型大鼠的神经修复作用。方法 将60只大鼠纳入对照组、模型组、奥氮平低、中、高剂量组,各组均10只。模型组、奥氮平低、中、高剂量组大鼠进行MK-801腹腔注射0.2 mg/(kg·d),对照组注射等量生理盐水。模型建立成功24 h后,奥氮平低、中、高剂量组分别以0.5、1.0、1.5 mg/(kg·d)奥氮平溶液灌胃,对照组、模型组同剂量生理盐水灌胃。按照共济失调和刻板行为标准对大鼠行为学进行评分;Morris水迷宫实验评定大鼠认知功能及学习能力;ELISA法检测大鼠血清肿瘤坏死因子α(TNF-α)和白细胞介素6(IL-6)水平;观察海马组织病理学变化;检测海马区细胞凋亡及CREB/BDNF/TrkB通路相关蛋白表达。结果 与对照组比较,模型组大鼠共济失调、刻板行为评分、TNF-α、IL-6表达、细胞凋亡率极显著增加(P<0.01),奥氮平低、中剂量组显著增加(P<0.05)。与对照组比较,模型组大鼠跨越平台次数、目标象限停留时间、CREB、磷酸化CREB(p-CREB)、磷酸化TrkB(p-TrkB)、TrkB、BDNF蛋白相对表达极显著减少(P<0.01),奥氮平低、中剂量组显著减少(P<0.05)。与模型组比较,奥氮平低、中剂量组跨越平台次数、目标象限停留时间显著增加(P<0.05),奥氮平高剂量组极显著增加(P<0.01)。模型组以及奥氮平低剂量组中海马细胞肿大明显、细胞核破碎分裂、固缩,组织排列杂乱;奥氮平中、高剂量组大鼠海马细胞中少见破碎分裂以及核固缩现象,整体组织与对照组大鼠相似。结论 奥氮平对精神分裂症模型大鼠的神经修复作用机制涉及到改善大鼠认知功能受损、保护大鼠海马神经细胞以及激活CREB/BDNF/TrkB信号通路的表达。

右美托咪定对癫痫大鼠海马神经元凋亡及BDNF/TrκB信号通路的影响

目的探究右美托咪定对癫痫大鼠海马神经元凋亡及脑源性神经营养因子(BDNF)/酪氨酸激酶受体B(Trκ狟)信号通路的影响。方法腹腔注射氯化锂-硫酸阿托品-盐酸匹罗卡品构建癫痫大鼠模型。将建模成功的36只大鼠随机分为模型组、右美托咪定(50μg/kg)组、右美托咪定(50μg/kg)+LM22B-10(BDNF/TrκB狟通路激活剂,5 mg/kg)组,每组12只,另取12只大鼠作为对照组。建模结束后各组大鼠给予对应药物干预,每天1次,连续1周。给药结束24 h后,观察记录各组大鼠癫痫发作频率和持续时间;TUNEL染色观察海马神经元细胞凋亡情况;免疫荧光染色检测海马CA_(1)区脑组织中β-微管蛋白Ⅲ(Tuj1)阳性细胞情况;酶联免疫吸附法检测海马CA_(1)区脑组织中肿瘤坏死因子(TNF)-α、白介素(IL)-6水平;蛋白印迹法检测海马CA_(1)区脑组织中BDNF、TrκB、B细胞淋巴瘤-2相关X蛋白(Bax)、B细胞淋巴瘤-2(Bcl-2)蛋白表达。结果与对照组相比,模型组大鼠癫痫发作频率、持续时间、海马神经元凋亡细胞数目、海马CA_(1)区脑组织TNF-α、IL-6水平、BDNF、TrκB、Bax蛋白表达水平显著升高(P<0.05);海马CA_(1)区脑组织Tuj1阳性细胞数目、Bcl-2蛋白表达水平显著降低(P<0.05);与模型组相比,右美托咪定组大鼠癫痫发作频率、持续时间、海马神经元凋亡细胞数目、海马CA_(1)区脑组织TNF-α、IL-6水平、BDNF、TrκB、Bax蛋白表达水平显著降低(P<0.05);海马CA_(1)区脑组织Tuj1阳性细胞数目、Bcl-2蛋白表达水平显著升高(P<0.05);LM22B-10能部分逆转右美托咪定对癫痫大鼠各项指标的改善作用(P<0.05)。结论右美托咪定能降低癫痫大鼠的癫痫发作以及抑制海马神经元的凋亡,减轻大鼠炎症反应,其机制可能与抑制BDNF/TrκB信号通路的激活有关。

胃癌组织中Survivin、TrkB和BDNF的表达及意义

目的观察生存素基因蛋白（Survivin）、酪氨酸激酶受体B（TrkB）及其配体脑源性神经营养因子（BDNF）在胃癌组织和癌旁黏膜中的表达情况，探讨和分析Survivin、TrkB和BDNF与胃癌临床病理学参数的关系。方法采用免疫组化sP法检测64例原发性胃癌组织、癌旁黏膜组织和34例淋巴结癌转移组中对应的阳性淋巴结Survivin、TrkB和BDNF蛋白的表达，分析其与临床病理学特征的关系。结果胃癌组织中Survivin、TrkB和BDNF蛋白的阳性表达率分别为71．87％（46／64）、60．93％（39／64）和59．37％（38／64），而癌旁黏膜组织无一例表达。Survivin、TrkB和BDNF蛋白表达与患者性别、年龄、肿瘤分化程度等无关（P〉0．05），而与浸润深度、淋巴结转移和TNM分期有关。浸润至胃壁全层组、有淋巴结转移组和TNM分期Ⅲ～Ⅳ组的Survivin、TrkB和BDNF阳性表达率明显高于未浸润至胃壁全层组、无淋巴结转移组和TNM分期Ⅰ～Ⅱ组（分别P〈0．01）。研究还显示，Survivin与TrkB和BDNF的阳性表达率随着肿瘤不同浸润深度、有无淋巴结转移呈现相同的变化趋势，相关分析表明，Survivin阳性表达与TrkB和BDNF呈正相关（P〈0．05）。胃癌转移组Survivin、TrkB和BDNF蛋白在淋巴结转移癌中的阳性表达率（82．35％，28／34；76．47％，26／34；70．58％，24／34）均较原发癌（88．23％，30／34；85．29％，29／34；82．35％，28／34）低，但两者差异无显著性（分别P〉0．05）。结论Survivin、TrkB和BDNF表达与胃癌发生发展密切相关，联合检测Survivin、TrkB和BDNF可有助于判断胃癌局部侵袭和远处转移的能力。

AMPA受体介导氯胺酮抗抑郁大鼠海马BDNF及TrkB变化

目的观察α-氨基-3-羟基-5-甲基-4-异恶唑(AMPA)受体介导氯胺酮抗抑郁过程中大鼠海马脑源性神经营养因子(BDNF)及酪氨酸受体激酶B(TrkB)的表达变化。方法 80只Wistar雄性大鼠随机均分为八组:第一部分包括二甲基亚砜(DMSO)+生理盐水(V1组)、DMSO+氯胺酮(V2组)、AMPA受体阻断剂(NBQX)5mg/kg+氯胺酮(N5组)、NBQX10mg/kg+氯胺酮(N10组);第二部分包括DMSO+酒精+生理盐水(V3组)、DMSO+酒精+氯胺酮(V4组)、AMPA受体激动剂(CX546)1mg/kg+生理盐水(C0组)、CX5461mg/kg+氯胺酮组(C1组)。干预前1d大鼠强迫游泳15min,干预当天分别进行DMSO、NBQX及CX546预处理,30min后给予1ml生理盐水或氯胺酮10mg/kg。第2次给药后30min强迫游泳,记录5min内不动时间,随后取海马组织检测BDNF及TrkB表达。结果与V2组比较,N5组及N10组大鼠强迫游泳不动时间增加,海马BD-NF、TrkB表达减少(P<0.05)。与V4组比较,C1组大鼠强迫游泳不动时间减少,海马BDNF、TrkB表达增加(P<0.05)。结论 AMPA受体介导氯胺酮抗抑郁作用,这可能与海马组织中BDNF和TrkB表达上调有关。