Hippocampal SorCS2 overexpression represses chronic stress-induced depressive-like behaviors by promoting the BDNF-TrkB system.

BACKGROUND: Emerging data has demonstrated that in mature neurons, SorCS2 localizes to the postsynaptic density of dendritic spines and facilitates plasma membrane sorting of TrkB by interacting with it, transmitting positive signaling from BDNF on neurons. Thus, it is possible that SorCS2 plays a role in the pathophysiology of depression by regulating the BDNF-TrkB system. METHODS: In the present study, SorCS2 expression in different brain regions [hippocampus, medial prefrontal cortex (mPFC), hypothalamus, amygdala, ventral tegmental area (VTA), and nucleus accumbens (NAc)] was thoroughly investigated in the chronic social defeat stress (CSDS) and chronic unpredictable mild stress (CUMS) models of depression. The changes in depressive-like behaviors, the hippocampal BDNF signaling cascade, and amounts of hippocampal immature neurons were further investigated after SorCS2 overexpression by microinjection of the adenovirus associated virus vector containing the coding sequence of mouse SorCS2 (AAV-SorCS2) into the hippocampus of mice exposed to CSDS or CUMS. RESULTS: It was found that both CSDS and CUMS significantly decreased the protein and mRNA expression of SorCS2 in the hippocampus but not in other brain regions. Chronic stress also notably downregulated the level of hippocampal SorCS2-TrkB binding in mice. In contrast, AAV-based genetic overexpression of hippocampal SorCS2 fully reversed the chronic stress-induced not only depressive-like behaviors but also decreased SorCS2-TrkB binding, BDNF signaling pathway, and amounts of immature neurons in the hippocampus of mice. CONCLUSION: All these results suggest that enhancing the hippocampal SorCS2 expression protects against chronic stress, producing antidepressant-like actions. Hippocampal SorCS2 may participate in depression neurobiology and be a potential antidepressant target. SIGNIFICANCE STATEMENT: Targeting of proteins to distinct subcellular compartments is essential for neuronal activity and modulated by VPS10P domain receptors which include SorCS2. In mature neurons, SorCS2 localizes to the postsynaptic density of dendritic spines and facilitates plasma membrane sorting of TrkB by interacting with it, transmitting positive signaling from BDNF on neurons. Our study is the first direct evidence preliminarily showing that SorCS2 plays a role in depression neurobiology. It was found that chronic stress induced not only depressive-like behaviors but also decreased SorCS2 expression in the hippocampus. Chronic stress did not affect SorCS2 expression in the mPFC, hypothalamus, amygdala, VTA, or NAc. In contrast, genetic overexpression of hippocampal SorCS2 prevented against chronic stress, producing antidepressant-like actions in mice. Thus, hippocampal SorCS2 is a potential participant underlying depression neurobiology and may be a novel antidepressant target. Our study may also extend the knowledge of the neurotrophic hypothesis of depression.

TrkB-mediated neuroprotection in female hippocampal neurons is autonomous, estrogen receptor alpha-dependent, and eliminated by testosterone: a proposed model for sex differences in neonatal hippocampal neuronal injury.

BACKGROUND: Neonatal hypoxia ischemia (HI) related brain injury is one of the major causes of learning disabilities and memory deficits in children. In both human and animal studies, female neonate brains are less susceptible to HI than male brains. Phosphorylation of the nerve growth factor receptor TrkB has been shown to provide sex-specific neuroprotection following in vivo HI in female mice in an estrogen receptor alpha (ERα)-dependent manner. However, the molecular and cellular mechanisms conferring sex-specific neonatal neuroprotection remain incompletely understood. Here, we test whether female neonatal hippocampal neurons express autonomous neuroprotective properties and assess the ability of testosterone (T) to alter this phenotype. METHODS: We cultured sexed hippocampal neurons from ERα+/+ and ERα-/- mice and subjected them to 4 h oxygen glucose deprivation and 24 h reoxygenation (4-OGD/24-REOX). Sexed hippocampal neurons were treated either with vehicle control (VC) or the TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) following in vitro ischemia. End points at 24 h REOX were TrkB phosphorylation (p-TrkB) and neuronal survival assessed by immunohistochemistry. In addition, in vitro ischemia-mediated ERα gene expression in hippocampal neurons were investigated following testosterone (T) pre-treatment and TrkB antagonist therapy via q-RTPCR. Multifactorial analysis of variance was conducted to test for significant differences between experimental conditions. RESULTS: Under normoxic conditions, administration of 3 µM 7,8-DHF resulted an ERα-dependent increase in p-TrkB immunoexpression that was higher in female, as compared to male neurons. Following 4-OGD/24-REOX, p-TrkB expression increased 20% in both male and female ERα+/+ neurons. However, with 3 µM 7,8-DHF treatment p-TrkB expression increased further in female neurons by 2.81 ± 0.79-fold and was ERα dependent. 4-OGD/24-REOX resulted in a 56% increase in cell death, but only female cells were rescued with 3 µM 7,8-DHF, again in an ERα dependent manner. Following 4-OGD/3-REOX, ERα mRNA increased ~ 3 fold in female neurons. This increase was blocked with either the TrkB antagonist ANA-12 or pre-treatment with T. Pre-treatment with T also blocked the 7,8-DHF- dependent sex-specific neuronal survival in female neurons following 4-OGD/24-REOX. CONCLUSIONS: OGD/REOX results in sex-dependent TrkB phosphorylation in female neurons that increases further with 7,8-DHF treatment. TrkB phosphorylation by 7,8-DHF increased ERα mRNA expression and promoted cell survival preferentially in female hippocampal neurons. The sex-dependent neuroprotective actions of 7,8-DHF were blocked by either ANA-12 or by T pre-treatment. These results are consistent with a model for a female-specific neuroprotective pathway in hippocampal neurons in response to hypoxia. The pathway is activated by 7,8-DHF, mediated by TrkB phosphorylation, dependent on ERα and blocked by pre-exposure to T.

TrkB-mediated sustained neuroprotection is sex-specific and Erα-dependent in adult mice following neonatal hypoxia ischemia.

BACKGROUND: Neonatal hypoxia ischemia (HI) related brain injury is one of the major causes of life-long neurological morbidities that result in learning and memory impairments. Evidence suggests that male neonates are more susceptible to the detrimental effects of HI, yet the mechanisms mediating these sex-specific responses to neural injury in neonates remain poorly understood. We previously tested the effects of treatment with a small molecule agonist of the tyrosine kinase B receptor (TrkB), 7,8-dihydroxyflavone (DHF) following neonatal HI and determined that females, but not males exhibit increased phosphorylation of TrkB and reduced apoptosis in their hippocampi. Moreover, these female-specific effects of the TrkB agonist were found to be dependent upon the expression of Erα. These findings demonstrated that TrkB activation in the presence of Erα comprises one pathway by which neuroprotection may be conferred in a female-specific manner. The goal of this study was to determine the role of Erα-dependent TrkB-mediated neuroprotection in memory and anxiety in young adult mice exposed to HI during the neonatal period. METHODS: In this study, we used a unilateral hypoxic ischemic (HI) mouse model. Erα+/+ or Erα-/- mice were subjected to HI on postnatal day (P) 9 and mice were treated with either vehicle control or the TrkB agonist, DHF, for 7 days following HI. When mice reached young adulthood, we used the novel object recognition, novel object location and open field tests to assess long-term memory and anxiety-like behavior. The brains were then assessed for tissue damage using immunohistochemistry. RESULTS: Neonatal DHF treatment prevented HI-induced decrements in recognition and location memory in adulthood in females, but not in males. This protective effect was absent in female mice lacking Erα. The female-specific improved recognition and location memory outcomes in adulthood conferred by DHF therapy after neonatal HI tended to be or were Erα-dependent, respectively. Interestingly, DHF triggered anxiety-like behavior in both sexes only in the mice that lacked Erα. When we assessed the severity of injury, we found that DHF therapy did not decrease the percent tissue loss in proportion to functional recovery. We additionally observed that the presence of Erα significantly reduced overall HI-associated mortality in both sexes. CONCLUSIONS: These observations provide evidence for a therapeutic role for DHF in which TrkB-mediated sustained recovery of recognition and location memories in females are Erα-associated and dependent, respectively. However, the beneficial effects of DHF therapy did not include reduction of gross tissue loss but may be derived from the enhanced functioning of residual tissues in a cell-specific manner.

Periods of low oxygen delivery and blood flow to the brains of newborns are known to cause life-long impairments to their cognitive ability as adults. Interestingly, male newborns are more susceptible to this injury than females. The mechanisms causing this sex difference are poorly understood. Here we test the role of the nerve growth factor receptor tyrosine kinase B (TrkB) in providing long-term neuroprotection following neonatal hypoxia­ischemia (HI) in mice. We have previously shown that when mice are treated with the TrkB agonist 7,8-dihydroxyflavone (DHF) in the days following neonatal HI, the result is short-term neuroprotection only in females and this protection is dependent on the presence of the estrogen receptor alpha receptor ([Formula: see text]). In this study, we extend these observations by subjecting mice either with or without [Formula: see text] to HI. Some of the mice were then treated with DHF immediately after HI. As adults, we performed tests to assess the mice's memory and anxiety-like behavior. At the end of these tests, we assessed the brains for tissue loss. Our results show that as adults the DHF treatment following HI in neonatal mice preserved memory only in females and this effect was dependent on the presence of [Formula: see text]. In addition, DHF therapy triggered anxiety-like behavior in mice lacking [Formula: see text]. We also show that this neuroprotection is not dependent on preservation of brain tissue following the injury. These results provide insight into the mechanisms behind the female resistance to hypoxic ischemic episodes as newborns.

TrkB-mediated sustained neuroprotection is sex-specific and ERα dependent in adult mice following neonatal hypoxia ischemia.

Background: Neonatal hypoxia ischemia (HI) related brain injury is one of the major causes of life-long neurological morbidities that result in learning and memory impairments. Evidence suggests that male neonates are more susceptible to the detrimental effects of HI, yet the mechanisms mediating these sex-specific responses to neural injury in neonates remain poorly understood. We previously tested the effects of treatment with a small molecule agonist of the tyrosine kinase B receptor (TrkB), 7,8-dihydroxyflavone (DHF) following neonatal HI and determined that females, but not males exhibit increased phosphorylation of TrkB and reduced apoptosis in their hippocampi. Moreover, these female-specific effects of the TrkB agonist were found to be dependent upon the expression of ERα. These findings demonstrated that TrkB activation in the presence of ERα comprises one pathway by which neuroprotection may be conferred in a female-specific manner. The goal of this study was to determine the role of ERα-dependent TrkB-mediated neuroprotection in memory and anxiety in young adult mice exposed to HI during the neonatal period. Methods: In this study we used a unilateral hypoxic ischemic (HI) mouse model. ERα+/+ or ERα-/- mice were subjected to HI on postnatal day (P) 9 and mice were treated with either vehicle control or the TrkB agonist, DHF, for seven days following HI. When mice reached young adulthood, we used the novel object recognition, novel object location and open field tests to assess long-term memory and anxiety like behavior. The brains were then assessed for tissue damage using immunohistochemistry. Results: Neonatal DHF treatment prevented HI-induced decrements in recognition and location memory in adulthood in females, but not in males. This protective effect was absent in female mice lacking ERα. Thus, the female-specific and ERα-dependent neuroprotection conferred by DHF therapy after neonatal HI was associated with improved learning and memory outcomes in adulthood. Interestingly, DHF triggered anxiety like behavior in both sexes only in the mice that lacked ERα. When we assessed the severity of injury, we found that DHF therapy did not decrease the percent tissue loss in proportion to functional recovery. We additionally observed that the presence of ERα significantly reduced overall HI-associated mortality in both sexes. Conclusions: These observations provide evidence for a therapeutic role for DHF in which sustained recovery of memory in females is TrkB-mediated and ERα-dependent. However, the beneficial effects of DHF therapy did not include reduction of gross tissue loss but may be derived from the enhanced functioning of residual tissues in a cell-specific manner.

Cucurbitacin B Exerts Significant Antidepressant-Like Effects in a Chronic Unpredictable Mild Stress Model of Depression: Involvement of the Hippocampal BDNF-TrkB System.

BACKGROUND: Although depression has been a serious neuropsychiatric disorder worldwide, current antidepressants used in clinical practice have various weaknesses, including delayed onset and low rates of efficacy. Recently, the development of new antidepressants from natural herbal medicine has become one of the important research hotspots. Cucurbitacin B is a natural compound widely distributed in the Cucurbitaceae and Cruciferae families and has many pharmacological activities. The present study aimed to investigate whether cucurbitacin B possess antidepressant-like effects in mice. METHODS: The antidepressant-like effects of cucurbitacin B on mice behaviors were explored using the forced swim test, tail suspension test, open field test, sucrose preference test, and a chronic unpredictable mild stress model of depression together. Then, western blotting and immunofluorescence were used to examine the effects of cucurbitacin B on the brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling cascade and neurogenesis in the hippocampus of mice. Furthermore, BDNF-short hairpin RNA, K252a, and p-chlorophenylalanine methyl ester were adopted together to determine the antidepressant mechanism of cucurbitacin B. RESULTS: It was found that administration of cucurbitacin B indeed produced notable antidepressant-like effects in mice, which were accompanied with significant promotion in both the hippocampal BDNF-TrkB pathway and neurogenesis. The antidepressant mechanism of cucurbitacin B involves the hippocampal BDNF-TrkB system but not the serotonin system. CONCLUSIONS: Cucurbitacin B has the potential to be a novel antidepressant candidate.

Early 7,8-Dihydroxyflavone Administration Ameliorates Synaptic and Behavioral Deficits in the Young FXS Animal Model by Acting on BDNF-TrkB Pathway.

Fragile X syndrome (FXS) is the leading inherited form of intellectual disability and the most common cause of autism spectrum disorders. FXS patients exhibit severe syndromic features and behavioral alterations, including anxiety, hyperactivity, impulsivity, and aggression, in addition to cognitive impairment and seizures. At present, there are no effective treatments or cures for FXS. Previously, we have found the divergence of BDNF-TrkB signaling trajectories is associated with spine defects in early postnatal developmental stages of Fmr1 KO mice. Here, young fragile X mice were intraperitoneal injection with 7,8-Dihydroxyflavone (7,8-DHF), a high affinity tropomyosin receptor kinase B (TrkB) agonist. 7,8-DHF ameliorated morphological abnormities in dendritic spine and synaptic structure and rescued synaptic and hippocampus-dependent cognitive dysfunction. These observed improvements of 7,8-DHF involved decreased protein levels of BDNF, p-TrkBY816, p-PLCγ, and p-CaMKII in the hippocampus. In addition, 7,8-DHF intervention in primary hippocampal neurons increased p-TrkBY816 and activated the PLCγ1-CaMKII signaling pathway, leading to improvement of neuronal morphology. This study is the first to account for early life synaptic impairments, neuronal morphological, and cognitive delays in FXS in response to the abnormal BDNF-TrkB pathway. Present studies provide novel evidences about the effective early intervention in FXS mice at developmental stages and a strategy to produce powerful impacts on neural development, synaptic plasticity, and behaviors.

Dysfunction of the Brain-derived Neurotrophic Factor-Tyrosine Kinase B Signaling Pathway Contributes to Learning and Memory Impairments Induced by Neuroinflammation in Mice.

Accumulating evidence suggests that neuroinflammation is the main mechanism in cognitive dysfunction and that brain-derived neurotrophic factor (BDNF) is involved in learning and memory by binding to tyrosine kinase B (TrkB) receptors. Herein, we tested the roles of the BDNF-TrkB signaling pathway and its downstream cascade in lipopolysaccharide (LPS) induced cognitive dysfunction in mice. Mice were treated with LPS (0.25 mg/kg) for 7 days, and learning and memory function was evaluated by the novel object recognition test (NORT). Western blotting was performed to elucidate roles of the BDNF-TrkB signaling pathway and its downstream cascades in LPS mice. The NORT showed that LPS induced learning and memory deficits in mice. The levels of IL-1ß, IL-6, and TNF-α in the serum and central nervous system decreased in LPS mice. In addition, LPS reduced the protein levels of BDNF, p-TrkB, Bcl-2, p-ERK1/2, p-CaMK2, p-CREB and p-GluR1 and increased the expression of Bax in the hippocampus and medial prefrontal cortex regions. In the entorhinal cortex, the protein levels of BDNF, p-TrkB, Bcl-2, p-CaMK2 and p-CREB were decreased, and the protein level of Bax was increased in LPS mice. Interestingly, 7,8-DHF alleviated these disorders in LPS mice and improved learning and memory function; however, the TrkB antagonist ANA12 effectively reversed effects of 7,8-DHF. Therefore, we conclude that the BDNF-TrkB signaling pathway and its downstream cascades disorders in different regions are main mechanisms of cognitive dysfunction, and 7,8-DHF maybe useful as a new treatment for preventing or treating cognitive dysfunction induced by neuroinflammation in neurodegenerative diseases.

Retinal vascular recovery revealed by retinal imaging following neonatal hypoxia ischemia in mice: Is there a role for tyrosine kinase receptor modulation?

OBJECTIVE: Hypoxic ischemic encephalopathy (HIE) secondary to perinatal asphyxia leads to long-term visual disabilities. Dilated retinal exams in human newborns with HIE is an emerging diagnostic tool, but phenotypes of hypoxia ischemia (HI) related retinal vascular injury are unclear. 7,8-Dihydroxyflavone (7,8-DHF) is a TrkB agonist with protective effects on HI-related brain damage. We studied retinal vessels in a mouse model of neonatal HIE and the efficacy of 7,8-DHF in ameliorating HI-related retinal vascular injury. METHODS: C57BL6/J mice at post-natal day (P) 9 received unilateral left carotid artery ligation followed by exposure to 10 % oxygen for 50 min. Phosphate buffered saline or 7,8-DHF (5 mg/kg) were administered daily for 7 days intraperitoneally. Control groups of naïve or carotid artery ligation only mice were studied. Fluorescein angiography was performed in acute (two weeks post-exposure) and chronic (four weeks post-exposure) time points. Retinal artery width, retinal vein width, and collateral vessel length were quantified. RESULTS: Ligation of the common carotid artery alone caused retinal artery dilation in acute and chronic time points, but had no effect on retinal veins. At acute time point, HI caused increased retinal artery vasodilation, but was reversed by 7,8-DHF. HI caused short collateral vessel formation in ipsilateral eyes, rescued by 7,8-DHF treatment. CONCLUSION: Retinal artery vasodilation and collateral vessel formation due to HI were rescued by 7,8-DHF treatment. Retinal and collateral vessel monitoring could be diagnostic biomarkers for HI severity. Studies to elucidate mechanisms of 7,8-DHF action on retinal vessels could aid development of therapies for neonatal HI.

Cardiovascular Disease in Duchenne Muscular Dystrophy: Overview and Insight Into Novel Therapeutic Targets.

Duchenne muscular dystrophy (DMD) is a devastating disease affecting approximately 1 in every 3,500 male births worldwide. Multiple mutations in the dystrophin gene have been implicated as underlying causes of DMD. However, there remains no cure for patients with DMD, and cardiomyopathy has become the most common cause of death in the affected population. Extensive research is under way investigating molecular mechanisms that highlight potential therapeutic targets for the development of pharmacotherapy for DMD cardiomyopathy. In this paper, the authors perform a literature review reporting on recent ongoing efforts to identify novel therapeutic strategies to reduce, prevent, or reverse progression of cardiac dysfunction in DMD.

Electroacupuncture treatment improves motor function and neurological outcomes after cerebral ischemia/reperfusion injury.

Electroacupuncture (EA) has been widely used for functional restoration after stroke. However, its role in post-stroke rehabilitation and the associated regulatory mechanisms remain poorly understood. In this study, we applied EA to the Zusanli (ST36) and Quchi (LI11) acupoints in rats with middle cerebral artery occlusion and reperfusion. We found that EA effectively increased the expression of brain-derived neurotrophic factor and its receptor tyrosine kinase B, synapsin-1, postsynaptic dense protein 95, and microtubule-associated protein 2 in the ischemic penumbra of rats with middle cerebral artery occlusion and reperfusion. Moreover, EA greatly reduced the expression of myelin-related inhibitors Nogo-A and NgR in the ischemic penumbra. Tyrosine kinase B inhibitor ANA-12 weakened the therapeutic effects of EA. These findings suggest that EA can improve neurological function after middle cerebral artery occlusion and reperfusion, possibly through regulating the activity of the brain-derived neurotrophic factor/tyrosine kinase B signal pathway. All procedures and experiments were approved by the Animal Research Committee of Shanghai University of Traditional Chinese Medicine, China (approval No. PZSHUTCM200110002) on January 10, 2020.

Brain-derived neurotrophic factor in autoimmune inflammatory diseases (Review).

Numerous recent studies reported that brain-derived neurotrophic factor (BDNF) also exists in the peripheral blood to regulate the proliferation, differentiation and survival of lymphocytes. Besides the role of BDNF in neuron repair, circulatory BDNF also enhances the proliferation and reduces apoptosis of lymphocytes. Peripheral lymphocytes express both BDNF and its receptors. Increasing evidence has indicated that altered BDNF serum levels significantly affect patients with autoimmune inflammatory diseases and may also be linked to the pathogenesis of diseases. For instance, systemic lupus erythematosus, an autoimmune inflammatory disease involving multiple organs, is frequently linked to altered B lymphocyte function, imbalance of T-cell subpopulations and loss of immune tolerance, which dysregulates the immune regulatory network with excessive secretion of inflammatory cytokines. The present review summarized studies that suggest a potential link between circulatory BDNF and autoimmune inflammatory diseases.

Neuroprotective effect and mechanism of butylphthalide after cerebral ischemia-reperfusion injury in rats.

INTRODUCTION: To investigate the neuroprotective effect and mechanism of DL-3-n-butylphthalide (NBP) on the brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) and its downstream signalling pathway after cerebral ischemia/reperfusion injury (CIRI) in rats. MATERIAL AND METHODS: The middle cerebral artery occlusion/reperfusion (MCAO/R) model was used. Reperfusion was performed 2 h after ischemia, and 20 mg/kg of NBP was intraperitoneally injected. Neurological defect score and pathological changes were performed. Apoptotic cells were detected using in situ end-labelling with TUNEL. The expression of BDNF and TrkB proteins was measured by Western blot and immunohistochemical staining. BDNF mRNA, TrkB mRNA, protein kinase B (AKT) mRNA and caspase-3 mRNA expression were measured using real-time polymerase chain reaction (qPCR). RESULTS: After 24 h of reperfusion, the neurological defect score and the percentage of apoptotic cells in the ischemia/reperfusion group (I/R group) were higher than those in the ischemia/reperfusion + drug group (I/R + d group). The positive expressions of BDNF and TrkB mRNA and protein in the I/R + d group were obviously higher than those in the I/R group (p < 0.05). After intervention with the TrkB receptor inhibitor (K252a), the expression levels of BDNF and TrkB and AKT mRNA were significantly decreased in the ischemia/reperfusion + drug + TrkB receptor inhibitor group (I/R + d + R group) compared with the I/R + d group, however the caspase-3 mRNA expression level showed the reverse trend. The expressions of BDNF, TrkB and p-Akt proteins in the I/R + d group were remarkably higher than those in the I/R group at each time point, and reached the peak at 24 hours after reperfusion, which were earlier than that in the I/R group. CONCLUSIONS: Butylphthalide represents a neuroprotective effect after CIRI in rats and used within 24 h of early onset contributes to better prognosis. The underlying mechanism may be related to reducing the apoptosis of nerve cells through BDNF/TrkB signalling pathway.

Estrogen administration attenuates post-stroke depression by enhancing CREB/BDNF/TrkB signaling in the rat hippocampus.

A previous study demonstrated that 17ß-estradiol (E2), which is an antidepressant, can ameliorate post-stroke depression (PSD); however, the underlying mechanisms governing this remain largely unknown. Therefore, the present study developed a PSD model in rats, which was induced by left middle cerebral artery occlusion followed by exposure to chronic mild stress for 2 weeks. The results revealed that the activity of the cAMP response element-binding protein (CREB), a cellular transcription factor, and the associated brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) signaling were all attenuated in the hippocampus in PSD rats. The depression-like behaviors were significantly improved after treatment with E2, along with increased CREB and the BDNF/TrkB signaling activity. These results provide novel insight into the molecular basis of PSD, and suggest the potential involvement of CREB/BDNF/TrkB signaling in E2-mediated improvement of PSD in rats.

Effect and Mechanism of Chaihu Jia Longgu Muli Tang on Hippocampus of Rats with Chronic Stress Depression Based on BDNF/TrkB/CREB Pathway / 中国实验方剂学杂志

Objective:To explore the effect of Chaihu Jia Longgu Muli Tang on the hippocampus of rats with chronic stress depression based on the brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB)/cyclic adenosine phosphate response element-binding protein (CREB) pathway. Method:Sixty SD rats were divided into a blank group (<italic>n</italic>=10) and an experimental group (<italic>n</italic>=50) for the induction of the chronic stress depression model. The rats in the experimental group were further divided into the following five groups: a model group， a fluoxetine hydrochloride group (0.003 g·kg^-1), and low-(1.625 g·kg^-1), medium-(3.25 g·kg^-1), and high-dose (6.5 g·kg^-1) Chaihu Jia Longgu Muli Tang groups. The rats were administered correspondingly by gavage once a day for eight weeks. Behavioral tests were performed to evaluate the depression state of the rats before modeling， after modeling， and after drug administration. Hematoxylin-eosin (HE) staining was used to observe the morphological changes in the hippocampus of rats. The immunohistochemical (IHC) staining was used to quantitatively detect BDNF protein expression in the rat hippocampus. The mRNA and protein expression of BDNF， TrkB， and CREB in the rat hippocampus was detected by the real-time fluorescence-based quantitative PCR (Real-time PCR) and Western blot， respectively. Result:Compared with the blank group， the model group showed decreased sucrose preference rate (<italic>P</italic><0.05)， declining horizontal and vertical scores (<italic>P</italic><0.05)， and prolonged immobility time and floating time (<italic>P</italic><0.05). Additionally， HE staining results revealed that hippocampal neuron structure was damaged. IHC staining showed that the mRNA and protein expression of BDNF， TrkB， and CREB was significantly decreased (<italic>P</italic><0.05). Compared with the model group， the fluoxetine hydrochloride group and the Chaihu Jia Longgu Muli Tang groups displayed elevated sucrose preference rate (<italic>P</italic><0.05)， increased horizontal and vertical scores (<italic>P</italic><0.05)， and shortened immobility time and floating time (<italic>P</italic><0.05). Furthermore, the hippocampal neuron structure was significantly repaired. IHC staining showed that the mRNA and protein expression of BDNF， TrkB， and CREB was significantly increased (<italic>P</italic><0.05). Conclusion:Chaihu Jia Longgu Muli Tang can significantly improve the depression-like behaviors of rats after chronic stress stimulation and enhance the regeneration and repair of neurons in the hippocampus. The underlying mechanism may be related to the up-regulation of the BDNF/TrkB/CREB signaling pathway in the hippocampus of rats.

Effects of Vortioxetine on depression model rats and expression of BDNF and Trk B in hippocampus.

Effects of Vortioxetine on the expression of brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (Trk B) in hippocampus of depressive rats were investigated. Forty-five SD rats were randomly divided into three groups: model control, Vortioxetine and normal control group, with 15 rats in each group. The changes of body mass were recorded within 5 weeks, and the open field test, sugar water preference test and Morris water maze test were performed to evaluate the behavior and mental status of the rats. The expression of BDNF and Trk B in rat hippocampus was detected by enzyme-linked immuno sorbent assay. Compared with the model control group, the body mass, horizontal and vertical movement, sugar and water preference rate of the vortioxetine group in the 5th week were significantly higher than those of the model control group (P<0.05), and significantly lower than those of the normal control group (P<0.05). The escape latency of the Vortioxetine group within 4 days was significantly lower than that of model control group (P<0.05), but higher than that of normal control group (P<0.05). The target quadrant residence time of the Vortioxetine group was significantly lower than that of the model control group (P<0.05), but higher than that of the normal control group (P<0.05). Expression of BDNF and Trk B in the Vortioxetine group was significantly higher than that in the model control group (P<0.05), but lower than that of the normal control group (P<0.05). Collectively, Vortioxetine can effectively alleviate the symptoms of autonomous and exploratory behavior, and reduce the decrease of learning and memory in depressive rats. Vortioxetine can increase the expression of BDNF and Trk B in depressive rats and alleviate their depressive behavior.

Study on Protection Effect of Mulberry Anthocyanin- 3-glucoside on Epilepsy Model Mice and the Effect of Hippocampal BDNF/TrkB Pathway / 中国药房

OBJECTIVE：To study the protection ef fects of mulberry anthocyanin- 3-glucoside on epilepsy model mice and the effect of hippocampal brain derived neurotrophic factor （BDNF）/tyrosine kinase B （TrkB）pathway. METHODS ：Totally 120 C57BL/6 mice were randomly divided into normal group ，model group ，single medication group （mulberry anthocyanin- 3- glucoside），agonist combination group（mulberry anthocyanin- 3-glucoside+TrkB agonist LM 22B-10），with 30 mice in each group. single medication group and agonist combination group were given mulberry anthocyanin- 3-glucoside 600 μg/kg intragastrically once a day ，for consecutive 6 weeks. The agonist combination group was given LM22B-10（5 mg/kg）via the lateral ventricle once a day at 6th week. Normal group and model group were given constant volume of normal saline intragastrically. After last medication，except for normal group ，other groups were given lithium chloride-pilocarpine to establish epilepsy model. After modeling，10 mice in each group were taken to record the latency ，frequency and duration of spontaneous recurrent epilepsy ， observed for 6 hours a day for 4 weeks；EEG was recorded on the 14th，28th and 36th day after modeling ，and the abnormal frequency of EEG in 1 h was counted . On the 6th day of modeling ，other 10 mice in each group were taken to detect the serum calcium level ，and the remaining 10 mice in each group were taken to detect the expressions of BDNF mRNA and protein in the hippocampus. RESULTS ：Compared with normal group ，latency，frequency and duration of spontaneous recurrent epilepsy and the times of abnormal brain wave on the 14th，28th and 36th day after modeling were increased significantly in model group （P＜ 0.05）. The serum calcium level ， mRNA and proteinexpression of BDNF in hippocampus were increased E-mail：wangfang7699@126.com significantly （P＜0.05）. Compared with model group ，the latency，frequency，duration of spontaneous recurrent epilepsy and the times of abnormal brain wave on the 28th and 36th day after modeling were decreased significantly in single medication group（P＜0.05），while serum calcium level ，mRNA and protein expression of BDNF in hippocampus were decreased significantly （P＜0.05）. Compared with single medication group ，the latency，frequency and duration of spontaneous recurrent epilepsy and the times of abnormal brain wave on the 28th and 36th day after modeling were increased significantly in agonist combination group （P＜0.05），while serum calcium level ，mRNA and protein expressions of BDNF in hippocampus were increased significantly （P＜0.05）. CONCLUSIONS ：Mulberry anthocyanin- 3- glucoside has a good protection effect on epilepsy model mice ，the mechanism of which may be associated with inhibiting the activation of hippocampal BDNF/TrkB pathway.

Peripheral blood brain-derived neurotrophic factor level and tyrosine kinase B expression on T lymphocytes in systemic lupus erythematosus: Implications for systemic involvement.

OBJECTIVE: Brain-derived neurotrophic factor (BDNF) has been reported to be involved in the pathogenesis of autoimmune diseases and tyrosine kinase B (TrkB) is the specific receptor for BDNF. Our aim in this study was to investigate serum BDNF level and TrkB expression on peripheral blood T cell surface in patients with systemic lupus erythematosus (SLE) and explore potential relationship between serum BDNF and SLE. METHODS: Samples from fifty SLE patients and thirty healthy controls were evaluated. Serum BDNF level was measured by enzyme-linked immunosorbent assay (ELISA) and the percentages of TrkB expression on the surface of CD3 + CD4 + and CD3 + CD8 + T lymphocytes were measured by flow cytometry. The SLE patients were divided into subgroups according to whether they exhibited brain, kidney or lung involvement, and whether the disease was active or inactive. RESULTS: Serum BDNF levels in SLE patients were decreased when compared to the controls (p < 0.001). Comparing with the SLE individuals without systemic involvement, the BDNF levels were decreased in SLE patients with lupus nephritis (p = 0.042) and in SLE patients with neuropsychiatric manifestations (p = 0.04). On the other hand, the BDNF level was significantly increased in the inactive SLE group (p < 0.001) compared to the active SLE group. In addition, the percentages of TrkB expression on CD3 + CD4 + and CD3 + CD8 + T cell surface in SLE were significantly higher (p < 0.001; p < 0.001, respectively) than that in the controls. CONCLUSIONS: Serum BDNF level combined with TrkB expression on T cell surface can reflect SLE activity. It is possible that BDNF may be used as a potential serological biomarker for disease activity of SLE. In addition, the significant decrease in serum BDNF level may imply systemic involvement of SLE, as well as, possibly, differentiate neuropsychiatric SLE from hormone-induced mental disorders.

Downregulated hippocampal expression of brain derived neurotrophic factor and tyrosine kinase B in a rat model of comorbid epilepsy and depression.

OBJECTIVE:  To investigate the expression of brain-derived neurotrophic factor(BDNF) and tyrosine kinase B (TrkB) protein in the hippocampus of model rats of comorbid epilepsy and depression. METHODS: A rat model of epilepsy was established using lithium chloride.pilocarpine. Among these epileptic rats, those with comorbid depression were selected by a battery of behavioral tests starting on the 14th day after establishing the epilepsy model. A depression group was established by unpredicted chronic mild stress (UCMS) and separate housing. These treatment groups were compared to an untreated control group. Thirteen rats per group were examined by immunofluorescence staining with optical density quantitation to determine the distribution of BDNF- and TrkB-positive cells in the hippocampus and by western blotting to estimate total protein expression levels during the 4th week after establishing the models. Immunofluorescence staining for NeuN was also conducted in hippocampus to evaluate neuronal survival. Depression-like behaviors were also assessed. RESULTS:  Compared to the untreated control group and the epilepsy alone group, the comorbid group exhibited lower average optical densities of BDNF- and TrkB-immunopositive cells as well as lower total BDNF and TrkB protein expression levels (all P = 0.000). The comorbid group exhibited lower behavioral scores compared to all other groups (all P=0.000). Numbers of NeuN-positive cells were lower in the hippocampus of all three experimental groups compared to the untreated control group (all P = 0.000). CONCLUSIONS:  These results suggest that hypofunctional BDNF-TrkB signaling may contribute to depression in epilepsy. ABBREVIATIONS: BDNF: Brain-derived neurotrophic factor; TrkB: tyrosine kinase B; UCMS: unpredicted chronic mild stress; PBS: phosphate-buffered saline; HS: Hippocampal sclerosis.

Brain-derived neurotrophic factor induces thioredoxin-1 expression through TrkB/Akt/CREB pathway in SH-SY5Y cells.

Brain-derived neurotrophic factor (BDNF) is one of the neurotrophic factors that are vital to the survival and proliferation of neuron. Thioredoxin-1 (Trx-1) is a redox regulating protein and plays various roles in regulating transcript factors and inhibiting apoptosis. It has been reported that Trx-1 is required for nerve growth factor-mediated signal transduction and neurite outgrowth, and is involved in synaptic protein expression induced by BDNF. However, the molecular mechanism on BDNF inducing Trx-1 expression has not been fully verified. The present study investigated the expression of Trx-1 after treatment with BDNF in SH-SY5Y cells. We first demonstrated that cell viability and the expression of Trx-1 were increased by BDNF in SH-SY5Y cells, which were inhibited by the tyrosine kinase B (TrkB) inhibitor, K252a, and the phosphatidylinositol 3-kinase (PI3-K) inhibitor, LY294002. Moreover, BDNF increased the activity of cAMP response element-binding protein (CREB) through TrkB/PI3-K/Akt pathway. Whereas the expression of Trx-1 induced by BDNF was suppressed by CREB siRNA. Thus, our data suggest that BDNF induces the expression of Trx-1 through the TrkB/Akt/CREB pathway.

Consuming egg yolk decreases body weight and increases serum HDL and brain expression of TrkB in male SD rats.

BACKGROUND: Egg yolks contain large amounts of cholesterol and are suspected to be harmful after long-term consumption. In this experiment, 63 rats were used to evaluate the effect of egg white (EW) and egg yolk (EY) supplementation on serum lipids and brain cognition. The feeding time lasted 4 weeks after a 1-week acclimation. RESULTS: Body weight was significantly higher in rats fed 132.0 g kg-1 EW and significantly lower when fed 40 g kg-1 EY (P < 0.05). Total cholesterol and low-density lipoprotein increased in rats fed 72.0 g kg-1 EW compared with rats from NC and EY groups (P < 0.05). High-density lipoprotein (HDL) was higher in rats fed 40 g kg-1 EY and decreased when fed 72.0 g kg-1 EW (P < 0.05). Rats fed a diet with EY exhibited abundant neurons in the CA1 hippocampus and complete subcellular structures. Rats fed 132 g kg-1 EW exhibited shrunken cells and swollen mitochondria. Brain-derived neurotrophic factor had constitutively low expression among groups, while tyrosine kinase B (TrkB) exhibited higher expression levels in rats fed a diet containing EY compared with other groups (P < 0.05). CONCLUSION: EY consumption reduced body weight and increased HDL levels. Diet containing EY could improve cognition through enhanced trkB expression. © 2019 Society of Chemical Industry.