Effects of endogenous neurotrophins on sympathetic sprouting in the dorsal root ganglia and allodynia following spinal nerve injury

Peripheral nerve injury is often complicated by a chronic pain syndrome that is difficult to treat. In animal models of peripheral nerve injury, sympathetic nerve terminals in the dorsal root ganglia (DRG) sprout to form baskets around large diameter neurons, an anatomical change that has been implicated in the induction of neuropathic pain. In the present study, we have investigated whether neurotrophins derived from peripheral sources play any roles in sympathetic sprouting and neuropathic pain in a rat model of peripheral nerve injury. After transection of the left lumbar (L) 5 spinal nerve, antisera specific to neurotrophins were injected intraperitoneally twice a week for 2 weeks. The foot withdrawal response to von Frey hairs was examined on days 1, 3, 7, 10, and 14 postlesion. After completion of behavioral tests, sympathetic sprouting in DRG was examined by tyrosine hydroxylase (TH) immunohistochemistry. The number of TH-immunoreactive (ir) fibers and baskets around large neurons within the lesioned DRG was dramatically increased in the rats treated with control normal sheep serum. Antisera specific to nerve growth factor (NGF), neurotrophin-3 (NT3), and brain-derived neurotrophic factor (BDNF) significantly reduced the sympathetic sprouting and the formation of baskets. L5 spinal nerve lesion induced a significant increase in foot withdrawal responses to von Frey hair stimuli, which was attenuated by treatment of antisera to neurotrophins with a different time sequential. The effect of BDNF antiserum occurred earlier and lasted longer than those of NGF and NT3 antisera. These results implicate that peripherally derived neurotrophins are involved in the induction of sympathetic sprouting and neuropathic pain following peripheral nerve injury.     

Developmental expression of neurotrophins and their receptors in postnatal rat ventral midbrain

Neurotrophins are a group of structurally related polypeptides that support the survival, differentiation, and maintenance of neuronal populations that express the appropriate high-affinity neurotrophin receptors. Two members of the neurotrophin family, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), have been shown to increase the survival of dopaminergic neurons from the ventral midbrain in vitro. Evidence suggests that ventral midbrain neurons might be able to derive support from these trophic factors in vivo through paracrine or autocrine interactions. Both BDNF and NT-3 mRNAs and their receptor mRNAs, trkB and trkC mRNAs, respectively, have been localized to the ventral mesencephalon. However, the relative expression levels of the neurotrophins and their receptor mRNAs throughout ontogeny and in adulthood have not been elucidated. In the present study, the postnatal developmental expression of BDNF, NT-3, trkB, and trkC mRNAs was analyzed via in situ hybridization to gain insight into the possible role of these factors in vivo. We found that there was a developmental decline in the expression of BDNF and NT-3 mRNAs in the ventral mesencephalon. In contrast, no alterations in the expression of midbrain trkB or trkC mRNAs could be discerned. The present results suggest a role for BDNF and NT-3 in the earlier postnatal developmental events of responsive populations. The continued, albeit lower, expression of the neurotrophins in the ventral mesencephalon in adulthood also suggests a role for these factors in mature neuronal systems.     

Developmental expression of neurotrophins and their receptors in postnatal rat ventral midbrain

Neurotrophins are a group of structurally related polypeptides that support the survival, differentiation, and maintenance of neuronal populations that express the appropriate high-affinity neurotrophin receptors. Two members of the neurotrophin family, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), have been shown to increase the survival of dopaminergic neurons from the ventral midbrain in vitro. Evidence suggests that ventral midbrain neurons might be able to derive support from these trophic factors in vivo through paracrine or autocrine interactions. Both BDNF and NT-3 mRNAs and their receptor mRNAs, trkB and trkC mRNAs, respectively, have been localized to the ventral mesencephalon. However, the relative expression levels of the neurotrophins and their receptor mRNAs throughout ontogeny and in adulthood have not been elucidated. In the present study, the postnatal developmental expression of BDNF, NT-3, trkB, and trkC mRNAs was analyzed via in situ hybridization to gain insight into the possible roles of these factors in vivo. We found that there was a developmental decline in the expression of BDNF and NT-3 mRNAs in the ventral mesencephalon. In contrast, no alterations in the expression of midbrain trkB or trkC mRNAs could be discerned. The present results suggest a role for BDNF and NT-3 in the earlier postnatal developmental events of responsive populations. The continued, albeit lower, expression of the neurotrophins in the ventral mesencephalon in adulthood also suggests a role for these factors in mature neuronal systems.     

Effects of glossopharyngeal nerve section on the expression of neurotrophins and their receptors in lingual taste buds of adult mice

The expression of neurotrophins and neurotrophin receptors is essential for the proper establishment and function of many sensory systems. To determine which neurotrophins and neurotrophin receptors are expressed in taste buds, and in taste buds of mice following denervation, antibodies directed against the neurotrophins and their receptors were applied to adult mouse gustatory tissue. Immunohistochemistry reveals that nerve growth factor (NGF)-like immunoreactive (LIR), tyrosine kinase (trk) A-LIR, trkB-LIR, and p75-LIR elongated, differentiated taste cells are present within all lingual taste buds, whereas neither neurotrophin (NT)-3- nor trkC-LIR was detected in taste cells. Double-label immunohistochemistry using markers of different taste cell types in brain-derived neurotrophic factor (BDNF)LacZ mice reveals that BDNF (beta-gal) and trkB colocalize, mainly in type III taste cells. NGF, pro-NGF, and trkA coexist in type II taste cells, i.e., those expressing phospholipase Cbeta2 (PLCbeta2). p75-LIR also is present in both BDNF and NGF taste cell populations. To determine the neural dependence of neurotrophin expression in adult taste buds, glossopharyngeal nerves were cut unilaterally. During the period of denervation (10 days to 3 weeks), taste buds largely disappear, and few neurotrophin-expressing cells are present. Three weeks after nerve transection, nerve fascicles on the operated side of the tongue exhibit BDNF-LIR, NGF-LIR, and ubiquitin carboxyl terminal hydrolase (PGP 9.5)-LIR. However, BDNF-LIR staining intensity but not NGF-LIR or PGP 9.5-LIR is increased in nerve fascicles on the operated compared with the unoperated side. Five weeks following nerve transection, NT and NT receptor expression resumes and appears normal in taste buds and nerves. These results indicate that neurotrophin expression in taste buds is dependent on gustatory innervation, but expression in nerves is not dependent on contact with taste buds.     

Changes in truncated trkB and p75 receptor expression in the rat spinal cord following spinal cord hemisection and spinal cord hemisection plus neurotrophin treatment

Although numerous studies have examined the effects of neurotrophin treatment following spinal cord injury, few have examined the changes that occur in the neurotrophin receptors following either such damage or neurotrophin treatment. To determine what changes occur in neurotrophin receptor expression following spinal cord damage, adult rats received a midthoracic spinal cord hemisection alone or in combination with intrathecal application of brain-derived neurotrophic factor (BDNF) or neurotrophin-3 (NT-3). Using immunohistochemical and in situ hybridization techniques, p75, trkA, trkB, and trkC receptor expression was examined throughout the spinal cord. Results showed that trkA, full-length trkB, and trkC receptors were not present in the lesion site but had a normal expression pattern in uninjured parts of the spinal cord. In contrast, p75 receptor expression occurred on Schwann cells throughout the lesion site. BDNF and NT-3 (but not saline) applied to the lesion site increased this expression. In addition, the truncated trkB receptor was expressed in the border between the lesion and intact spinal cord. Truncated trkB receptor expression was also increased throughout the white matter ipsilateral to the lesion and BDNF (but not NT-3 or saline) prevented this increase. The study is the first to show changes in truncated trkB receptor expression that extend beyond the site of a spinal cord lesion and is one of the first to show that BDNF and NT-3 affect Schwann cells and/or p75 expression following spinal cord damage. These results indicate that changes in neurotrophin receptor expression following spinal cord injury could influence the availability of neurotrophins at the lesion site. In addition, neurotrophins may affect their own availability to damaged neurons by altering the expression of the p75 and truncated trkB receptor.     

Nestin expression defines both glial and neuronal progenitors in postnatal sympathetic ganglia

Sympathetic ganglia are primarily composed of noradrenergic neurons and satellite glial cells. Although both cell types originate from neural crest cells, the identities of the progenitor populations at intermediate stages of the differentiation process remain to be established. Here we report on the identification in vivo of glial and neuronal progenitor cells in postnatal sympathetic ganglia, by using mouse superior cervical ganglia as a model system. There are significant levels of cellular proliferation in mouse superior cervical ganglia during the first 18 days after birth. A majority of the proliferating cells express both nestin and brain lipid-binding protein (BLBP). Bromodeoxyuridine (BrdU) fate-tracing experiments demonstrate that these nestin and BLBP double-positive cells represent a population of glial progenitors for sympathetic satellite cells. The glial differentiation process is characterized by a marked downregulation of nestin and upregulation of S100, with no significant changes in the levels of BLBP expression. We also identify a small number of proliferating cells that express nestin and tyrosine hydroxylase, a key enzyme of catecholamine biosynthesis that defines sympathetic noradrenergic neurons. Together, these results establish nestin as a common marker for sympathetic neuronal and glial progenitor cells and delineate the cellular basis for the generation and maturation of sympathetic satellite cells.     

Brain-derived neurotrophic factors increase the proliferation and differentiation of endogenous neural stem cells in mouse models of cerebral infarction

BACKGROUND： It has been confirmed that brain-derived neurotrophic factor （BDNF） can promote the proliferation of neural stem cells （NSCs） and protect neuron-like cells in vitro. However, its effect on endogenous NSCs in vivo is still unclear. OBJECTIVE： To evaluate whether BDNF can induce the endogenous NSCs to proliferate and differentiate into the neurons in the mice model of cerebral infarction. DESIGN： A synchronal controlled observation. SETTINGS： Department of Neurology, Microbiology Division of the Department of Laboratory, Tianjin First Central Hospital; Howard Florey Institute, Medical College, the University of Melbourne. MATERIALS： Twenty-four pure breed C57BL/6J mice at the age of 10 weeks old （12 males and 12 females） were divided into saline control group and BDNF-treated group, 6 males and 6 females in each group. METHODS： The experiments were performed at the University of Melbourne from July 2004 to February 2005. ① The left middle cerebral artery （MCA） was ligated in both groups to establish models of cerebral infarction and the Matsushita measuring method was used to monitor the blood flow of the lesioned region supplied by MCA. 75% reduction of blood flow should be reached in the lesioned region. ② At 24 hours after infarction, mice in the BDNF-treated group were administrated with BDNF, which was slowly delivered using an ALZET osmium pump design. BDNF was dissolved in saline at the dosage of 500 mg/kg and injected into the pump, which could release the solution consistently in the following 28 days. The mice in the saline control group accepted the same volume of saline at 24 hours after infarction. ③ The Rotarod function test began at 1 week preoperatively, the time stayed on Rotarod was recorded. The mice were tested once a day till the end of the experiment. At 4 weeks post cerebral infarction, double labeling of Nestin and GFAP, BIH tubulin and CNPase immunostaining was performed to observe the differentiation directions of the re-expressed endogenous NSCs, and the percentages of the cells differentiated into astrocytes, neurons and oligodendrocytes were calculated. MAIN OUTCOME MEASURES： ① The differentiation directions of the re-expressed endogenous NSCs, and the percentage of the cells differentiated into astrocytes, neurons and oligodendrocytes.② Comparison of motor function between the two groups. RESULTS： All the 24 pure C57BL/6J mice were involved in the analysis of results. ①Positively expressed endogenous NSCs appeared in the mice of both groups, and they mainly distributed around the focus of lesion, as well as the contralateral side. The expressed cells in the BDNF-treated group were obviously more than those in the saline control group. ②Activations of endogenous NSCs： At 4 weeks after infarction, re-expressions of endogenous NSCs appeared in both groups. The number of the re-expressed cells in the BDNF-treated group was about 4.2 times higher than that in the saline control group. The percentage of the cells differentiated into neurons in the BDNF-treated group was significantly higher than that in the saline control group （36%, 15%）, the percentage of the cells differentiated into astrocytes was lower than that in the saline control group （54%, 77%）, whereas the percentage of the cells differentiated into oligodendrocytes was similar to that in the saline control group （10%, 8%）. ③ Results of motor functional test： Compared with before cerebral infarction, the mice in both groups manifested as obvious decrease in motor function at 1 week after infarction, whereas the recovery of motor function in the BDNF-treated group was significantly superior to that in the saline control group at 2, 3 and 4 weeks （P 〈 0.01）. CONCLUSION： BDNF can promote the proliferation of endogenous NSCs in the brain of mice with cerebral infarction, it can decrease the differentiation rate of astrocytes, and increase the differentiation rate of neurons. BDNF has small influence on the differentiation of endogenous NSCs into oligodendrocytes, which was not benefit for the recovery of neural axon. Endogenous NSCs may improve the motor function of mice through the above pathways.     

Brain-derived neurotrophic factors increase the proliferation and differentiation of endogenous neural stem cells in mouse models of cerebral infarction

BACKGROUND: It has been confirmed that brain-derived neurotrophic factor (BDNF) can promote the proliferation of neural stem cells (NSCs) and protect neuron-like cells in vitro. However, its effect on endogenous NSCs in vivo is still unclear. OBJECTIVE: To evaluate whether BDNF can induce the endogenous NSCs to proliferate and differentiate into the neurons in the mice model of cerebral infarction. DESIGN: A synchronal controlled observation. SETTINGS: Department of Neurology, Microbiology Division of the Department of Laboratory, Tianjin First Central Hospital; Howard Florey Institute, Medical College, the University of Melbourne. MATERIALS: Twenty-four pure breed C57BL/6J mice at the age of 10 weeks old (12 males and 12 females) were divided into saline control group and BDNF-treated group, 6 males and 6 females in each group. METHODS: The experiments were performed at the University of Melbourne from July 2004 to February 2005. ① The left middle cerebral artery (MCA) was ligated in both groups to establish models of cerebral infarction and the Matsushita measuring method was used to monitor the blood flow of the lesioned region supplied by MCA. 75% reduction of blood flow should be reached in the lesioned region. ② At 24 hours after infarction, mice in the BDNF-treated group were administrated with BDNF, which was slowly delivered using an ALZET osmium pump design. BDNF was dissolved in saline at the dosage of 500 mg/kg and injected into the pump, which could release the solution consistently in the following 28 days. The mice in the saline control group accepted the same volume of saline at 24 hours after infarction. ③ The Rotarod function test began at 1 week preoperatively, the time stayed on Rotarod was recorded. The mice were tested once a day till the end of the experiment. At 4 weeks post cerebral infarction, double labeling of Nestin and GFAP, BIII tubulin and CNPase immunostaining was performed to observe the differentiation directions of the re-expressed endogenous NSCs, and the percentages of the cells differentiated into astrocytes, neurons and oligodendrocytes were calculated. MAIN OUTCOME MEASURES: ① The differentiation directions of the re-expressed endogenous NSCs, and the percentage of the cells differentiated into astrocytes, neurons and oligodendrocytes. ② Comparison of motor function between the two groups. RESULTS: All the 24 pure C57BL/6J mice were involved in the analysis of results. ① Positively expressed endogenous NSCs appeared in the mice of both groups, and they mainly distributed around the focus of lesion, as well as the contralateral side. The expressed cells in the BDNF-treated group were obviously more than those in the saline control group. ②Activations of endogenous NSCs: At 4 weeks after infarction, re-expressions of endogenous NSCs appeared in both groups. The number of the re-expressed cells in the BDNF-treated group was about 4.2 times higher than that in the saline control group. The percentage of the cells differentiated into neurons in the BDNF-treated group was significantly higher than that in the saline control group (36%, 15%), the percentage of the cells differentiated into astrocytes was lower than that in the saline control group (54%, 77%), whereas the percentage of the cells differentiated into oligodendrocytes was similar to that in the saline control group (10%, 8%). ③ Results of motor functional test: Compared with before cerebral infarction, the mice in both groups manifested as obvious decrease in motor function at 1 week after infarction, whereas the recovery of motor function in the BDNF-treated group was significantly superior to that in the saline control group at 2, 3 and 4 weeks (P < 0.01). CONCLUSION: BDNF can promote the proliferation of endogenous NSCs in the brain of mice with cerebral infarction, it can decrease the differentiation rate of astrocytes, and increase the differentiation rate of neurons. BDNF has small influence on the differentiation of endogenous NSCs into oligodendrocytes, which was not benefit for the recovery of neural axon. Endogenous NSCs may improve the motor function of mice through the above pathways.     

Differential effects of neurotrophins on ocular dominance plasticity in developing and adult cat visual cortex

In the present study we examine the influence of neurotrophins on experience-dependent synaptic rearrangement in developing and adult visual cortex. Brain-derived neurotrophic factor (BDNF) or nerve growth factor (NGF) was continuously infused into cortical area 18, and the functional architecture of the cortex was examined by use of optical and electrophysiological recording techniques. In kittens, BDNF infusion during monocular deprivation (MD) reversed the normally occurring ocular dominance (OD) shift towards the non-deprived eye so that the deprived eye dominated the BDNF-treated cortex after MD. Under conditions of equal activation of thalamocortical synapses, i.e. when animals were either subject to binocular deprivation (BD) or reared without deprivation, BDNF infusion did not disrupt binocularity of cortical units, but reversed the natural OD bias towards the contralateral eye in favour of the ipsilateral eye. In addition, BDNF treatment in kittens led to a loss of the orientation selectivity of cortical units irrespective of rearing conditions. In adult animals, BDNF influenced neither OD distributions nor orientation selectivity. The effect of NGF was markedly different. It was ineffective in kittens but in adult animals it caused a shift of OD towards the deprived eye when MD was combined with NGF infusion. However, in this case orientation selectivity was preserved. Thus, both neurotrophins have profound activity- and age-dependent effects on the functional architecture of the visual cortex. Moreover, our results indicate that simple substitution of neurotrophins in excess is unlikely to compensate for deprivation effects by preserving or restoring the normal functional architecture of the cortex.     

BDNF预处理急性高眼压大鼠视网膜trkB及p-trkB的表达变化

检测BDNF干预后大鼠视网膜TrkB、磷酸化TrkB的表达变化,为受损后视网膜节细胞的保护及外源性BDNF的应用提供一定的理论基础。方法：成年大鼠部分左眼给予BDNF预处理,右眼均设为正常对照。左眼眼压升高至闪光视网膜电图b波消失的临界眼压并维持60min,分别存活1、3、7、14天后处死,冰冻切片行尼氏染色及TrkB、磷酸化TrkB的免疫组织化学染色。结果：急性高眼压组各时间点节细胞层细胞数目均显著少于BDNF预处理组;急性高眼压组在存活1天、3天时TrkB的表达明显增加,p-TrkB的表达显著下调,7天、14天时TrkB、p-TrkB的表达均下调;BDNF预处理组在存活1天、3天时TrkB的表达明显上调,p-TrkB的表达下调但显著高于同时间点的单纯高眼压组;7天时TrkB的表达下调至正常对照组水平,14天时又再次显著上调;p-TrkB的表达在7、14天时进一步下调,但仍高于同时间点的单纯高眼压组。结论：BDNF对急性高眼压后大鼠视网膜的保护作用依赖于TrkB的激活,根据TrkB的表达变化给予BDNF对急性高眼压后的大鼠视网膜有较好保护作用。     

缺血再灌注大鼠海马的神经干细胞移植：磷脂酰肌醇3/Akt通路激活和脑源性神经营养因子表达增加

背景：PI3K/Akt通路和BDNF在脑缺血动物模型和患者中表达异常,也成为的脑缺血的治疗靶点。神经干细胞在修复的潜在用途包括移植修复丢失的细胞和激活内源性细胞提供“自我修复。” 目的：观察神经干细胞植入对PI3K/Akt和BDNF在海马表达的影响,阐明神经干细胞植入对脑缺血的神经保护机制。 设计：完全随机分组,对照动物实验。 时间及地点：实验于2007-03-2008.09在南方医科大学基因工程研究所完成。 材料：E17的怀孕大鼠和雌性大鼠购自南方医科大学实验动物中心,兔抗PI3K的试剂盒购自北京博奥森生物科技公司,磷酸化Akt（Ser473）由美国Cell Signaling Technology提供,其他试剂由美国sigma和Santa Cruz公司提供。 方法：体外分离、培养大鼠NSCs,进行WTS-8、 BrdU检测。局灶性脑缺血模型,大脑中动脉线栓方法制作大鼠脑缺血再灌注模型。参照Longa氏5分评分方法,得分超过2分大鼠入选实验。2,3,5,氯化三苯基四唑（TTC）染色检测梗死体积。两天后大脑中动脉阻塞大鼠给与50000 E17的立体定向神经干细胞移植或5μgWortmannin至缺血海马旁。使用免疫印迹分析Akt（Ser473）,PI3K和BNDF的表达。 主要观察指标：脑组织神经干细胞移植激活PI3K/Akt通路参与促进神经组织的结构和功能恢复且上调脑源性神经营养因子的功能。 结果：神经干细胞治疗组脑梗死体积显着低于缺血模型组(P<0.01)、Wortmannin干预组(P<0.01)和神经干细胞+Wortmannin干预组(P<0.05)。在神经干细胞治疗组PI3K蛋白的水平比较显着高于脑缺血模型性(P<0.01)。在Akt的蛋白质水平（Ser473）和神经干细胞治疗组BNDF更为显著高于脑缺血模型性(P<0.01)。在治疗组的BNDF蛋白水平比较显着高于Wortmannin干预(P<0.01)神经干细胞+Wortmannin干预组(P<0.05)。 结论：在脑缺血过程中神经干细胞移植激活PI3K/Akt通路参与脑源性神经营养因子的基因表达。     

Expression of neurotrophins BDNF and NT-3, and their receptors in rat brain after administration of antipsychotic and psychotrophic agents

We have investigated the potential role of neurotrophic factors in antipsychotic drug action by examining the effects of antipsychotic and psychotropic treatments on the mRNA expression of brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and their receptors, trkB and trkC, respectively, in rat brain. Neither acute nor chronic clozapine treatment significantly affected the expression of these mRNAs in any brain area investigated, except for a decrease in trkB expression in the granule cells of the olfactory bulb. We then examined the effects of the psychotropic agent MK-801. MK-801 (5 mg/kg; 4h) significantly increased BDNF mRNA in the entorhinal cortex, but did not influence NT-3, trkB, or trkC expression in any brain area except for the olfactory bulb. The induction of BDNF mRNA by MK-801 was attenuated by pre-treatment (1 h prior to MK-801 administration) with the antipsychotics, clozapine (25 mg/kg) and haloperidol (2 mg/kg), but not with the antidepressant desipramine (15 mg/kg). Finally, we confirmed that the effects of MK-801 on BDNF mRNA were reflected in the respective changes in BDNF protein levels: MK-801 significantly increased anti-BDNF reactivity in the entorhinal cortex (126 ± 7% of control) while concomitantly decreasing in the hippocampus (71 ± 2% of control). These data do not support the hypothesis that neurotrophins play an important role in antipsychotic drug action, but rather suggest that induction of BDNF in the entorhinal cortex may play a significant role in the psychotropic action of MK-801.     

Neuronal injury and brain-derived neurotrophic factor expression in a rat model of amygdala kindling seizures Differences in brain regions and kindling courses

BACKGROUND:Studies have demonstrated that brain-derived neurotrophic factor (BDNF) has a dual effect on epilepsy. However, the relationship between epilepsy-induced brain injury and BDNF remains poorly understood.OBJECTIVE:According to ultrastructural and molecular parameters, to detect the degree of neuronal injury and BDNF expression changes at different brain regions and different kindling times to determine the effects of BDNF on epilepsy-induced brain injury.DESIGN, TIME AND SETTING:A randomized, controlled, animal experiment based on neuropathology and molecular biology was performed at the Department of Physiology and Department of Pathology, Basic Medical College of Jilin University in 2003.MATERIALS:UltraSensitiveTM SP kit for immunohistochemistry (Fuzhou Maxim Biotechnology, China), BDNF antibody (concentrated type, Wuhan Boster Biological Technology, China), JEM-1000SX transmission electron microscopy (JEOL, Japan), and BH-2 light microscope (Olympus, Japan) were used in the present study.METHODS:Wistar rats were randomly assigned to control (n = 6), sham-surgery (n = 6), and model (n = 60) groups. The control group rats were not treated; an electrode was embedded into the amygdala in rats from the sham-surgery and model groups; an amygdala kindling epilepsy model was established in the model group.MAIN OUTCOME MEASURES:Pathological changes in the temporal lobe and hippocampus were observed by light and electron microscopy at 1, 3, 7, 14, and 21 days following kindling, and BDNF expression in the various brain regions was determined by immunohistochemistry.RESULTS:In the model group, temporal lobe cortical and hippocampal neurons were swollen and the nuclei were laterally deviated. There were also some apoptotic neurons 3 days after kindling. The nucleoli disappeared and the nuclei appeared broken or lysed, as well as slight microglia hyperplasia, at 7 days. Electron microscopic observation displayed chromatin aggregation in the nuclei and slight mitochondrion swelling 3 days after kindling. Injury changes were aggravated at 7 days, characterized by broken cytoplasmic membrane and pyknosis. With the development of seizure, the number of BDNF-positive neurons in the hippocampus and temporal lobe increased and peaked at 7 days. Moreover, hippocampal and cortical temporal lobe injury continued. Following termination of electrical stimulation after 7 days of kindling, BDNF expression decreased, but continued to be expressed, up to 21 days of kindling. In addition, the number of temporal and hippocampal BDNF-positive neurons was greater than the control group.CONCLUSION:Brain injury and BDNF expression peaked at 7 days after kindling, and hippocampal changes were significant.     

Interventional effect of laser acupoint radiation on the expression of Nissl body and brain-derived neurotrophic factor in newborn rat models with ischemic/hypoxic cerebral injury

BACKGROUND: Some researches report that He-Ne laser can activate function of erythrocytes and increase content of blood and oxygen via bio-stimulating effect; therefore, it suspects that laser radiation at Baihui and Dazhui can partially increase blood circulation for oxygen-supplying content of brain and improve functional status of neurons. OBJECTIVE: To verify the effects of laser radiation at Baihui and Dazhui on the expression of Nissl body of brain tissue neurons and brain-derived neurotrophic factor (BDNF) in newborn rats with ischemic/hypoxic cerebral injury. DESIGN: Randomized controlled animal study. SETTING: Department of Neurological Histochemistry, Xianning University. MATERIALS: Forty Wistar rats of 7–8 days old, weighing 15–20 g and of both genders, were selected from Wuhan Experimental Animal Center. All the rats were randomly divided into sham operation group (n =8), model group (n =16) and radiation group (n =16). The experimental animals were disposed according to ethical criteria. BDNF kit was provided by Wuhan Boster Bioengineering Co., Ltd. METHODS: The experiment was carried out in the Department of Neurological Histochemistry, Xianning University from April 2005 to October 2006. Rats in the radiation group and model group were performed with ligation of left common carotid artery, recovered at room temperature for 1–6 days, maintained in self-made hypoxic cabin under normal pressure and injected mixture gas (0.05 volume fraction of O2 and 0.92 volume fraction of N2) for 2 hours. In addition, rats in the sham operation group were treated with separation of left common carotid artery but not ligation and hypoxia. Rats in the model group were not given any treatment; while, rats in the radiation group were exposed with He-Ne laser of 63.28 nm in the wave length at Baihui and Dazhui acupoints on the second day after ischemia-hypoxia. The radiation was given for 10 minutes per day and once a day. Ten days were regarded as a course and the rats were exposed for 2 courses in total. At 20 days after routine breeding, left hemisphere tissues of rats in the three groups were collected for staining of Nissl body and immunohistochemistry of BDNF. MAIN OUTCOME MEASURES: Nissl body staining in left hemisphere tissue and expression of immune positive cells of BDNF. RESULTS: All 40 rats were involved in the final analysis. ① Nissl body staining: Neuronal cytoplasm of brain tissue was full of blue granule Nissl bodies in the sham operation group; while, Nissl body in neuronal cytoplasm in the model group was stained slightly and had a certain degree of degeneration; meanwhile, there were a lot of blank area in ischemic region. Nissl body in neuron cytoplasm was gradually recovered in the radiation group and relieved as compared with that in the model group. ② Positive cells of BDNF: Number of immune positive cells of BDNF which were ligated in lateral cerebral hemisphere of rats in the model group was higher than that in the sham operation group (P < 0.05); while, BDNF expression in the radiation group was increased as compared with that in the model group (P < 0.05). CONCLUSION: After laser acupoint radiation, Nissl body is increased and BDNF expression is also increased. This suggests that laser acupoint radiation has neuroprotective effect on brain tissue after ischemia-hypoxia injury.     

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 hipp     

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 Trk(B 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.     

Neurotrophins reduce degeneration of injured ascending sensory and corticospinal motor axons in adult rat spinal cord

Spinal cord regeneration in adult mammals is limited by neurite outgrowth inhibitors and insufficient availability of outgrowth-promoting agents. Formation of degenerative swellings at the proximal ends of severed axons (terminal clubs), which starts early after injury, also may hinder recovery and their rupture may contribute to secondary spinal cord damage. We investigated whether neurotrophins would reduce these degenerative processes. Adult rats received a transection of the dorsal column sensory and corticospinal motor tracts at T9 and anterograde tracing of the axons from the sciatic nerve and motor cortex, respectively. The highest number of terminal clubs was found at 1 day and approximately half remained present until at least 28 days. A single injection immediately after injury of a mixture of nerve growth factor, brain-derived neurotrophic factor and neurotrophin-3 into the lesion site, reduced the number of terminal clubs in the sensory system by approximately half at 1 and 7 days (but not 14) after the lesion. Individual or combinations of two neurotrophins were as effective, suggesting that the neurotrophins protected similar axonal populations. The injected neurotrophins did not affect degeneration of corticospinal motor axons. A 7-day continuous intrathecal infusion of neurotrophin-3 was more effective and also reduced terminal club formation of corticospinal axons by approximately 60%. Spinal tissue loss was not affected by the neurotrophin treatments, suggesting that terminal clubs are not major contributors to the pathogenesis of secondary spinal degeneration during the first two weeks. Thus, neurotrophins can reduce axonal degeneration in the spinal cord after traumatic axonal injury.     

Parallel expression of neurotrophic factors and their receptors in chronic inflammatory demyelinating polyneuropathy

The mRNA levels of nerve growth factor (NGF), glial cell line-derived neurotrophic factor (GDNF), ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), and interleukin-6 (IL-6) were examined in sural nerves of 22 patients with chronic inflammatory demyelinating polyneuropathy (CIDP). The mRNAs for NGF, GDNF, LIF, and IL-6 were upregulated, whereas CNTF mRNA was downregulated significantly in the nerves. The NGF, GDNF, and CNTF, but not LIF mRNA expressions were parallel to those of the cognate receptors, suggesting that these cognate soluble receptors effectively present these factors to maintain and regenerate the axons. Furthermore, IL-6 mRNA expression was significantly parallel to both binding and signal-transducing receptor expression, implying a role of the IL-6 signal for non-neuronal cells in CIDP. These findings indicate that multiple neurotrophic growth factors and cytokines are expressed cooperatively with their concomitant receptors in the nerve lesions of CIDP and play an important role particularly in nerve repair.