Overexpression of BDNF by Astrocytes Targeted Delivery of mRNA Ameliorates Cognitive Impairment in Mouse Model of TBI.

Muscle BDNF: a potential therapeutic target for Kennedy's disease.

Our recent study has indicated that a moderate lesion of the mesostriatal and mesolimbic pathways in rats, modelling preclinical stages of Parkinson’s disease, induces a depressive-like behaviour which is reversed by chronic treatment with pramipexole. The purpose of the present study was to examine the role of brain derived neurotrophic factor (BDNF) signalling in the aforementioned model of depression. Therefore, we investigated the influence of 6-hydoxydopamine (6-OHDA) administration into the ventral region of the caudate-putamen on mRNA levels of BDNF and tropomyosin-related kinase B (trkB) receptor. The BDNF and trkB mRNA levels were determined in the nigrostriatal and limbic structures by in situ hybridization 2 weeks after the operation. Pramipexole (1 mg/kg sc twice a day) and imipramine (10 mg/kg ip once a day) were injected for 2 weeks. The lesion lowered the BDNF and trkB mRNA levels in the hippocampus [CA1, CA3 and dentate gyrus (DG)] and amygdala (basolateral/lateral) as well as the BDNF mRNA content in the habenula (medial/lateral). The lesion did not influence BDNF and trkB expression in the caudate-putamen, substantia nigra, nucleus accumbens (shell and core) and ventral tegmental area (VTA). Chronic imipramine reversed the lesion-induced decreases in BDNF mRNA in the DG. Chronic pramipexole increased BDNF mRNA, but decreased trkB mRNA in the VTA in lesioned rats. Furthermore, it reduced BDNF and trkB mRNA expression in the shell and core of the nucleus accumbens, BDNF mRNA in the amygdala and trkB mRNA in the caudate-putamen in these animals. The present study indicates that both the 6-OHDA-induced dopaminergic lesion and chronic pramipexole influence BDNF signalling in limbic structures, which may be related to their pro-depressive and antidepressant activity in rats, respectively.

BackgroundThe aim of this study was to explore how changes in the expression of BDNF in MLDS change the effect of BDNF on dopamine (DA) neurons, which may have therapeutic implications for heroin addiction.Material/MethodsWe established a rat model of heroin addiction and observed changes in the expression of BDNF, DA, dopamine receptor (DRD), dopamine transporter (DAT), and other relevant pathways in NAc. We also assessed the effect of BDNF overexpression in the NAc, behavioral changes of heroin-conditioned place preference (CPP), and naloxone withdrawal in rats with high levels of BDNF. We established 5 adult male rat groups: heroin addiction, lentivirus transfection, blank virus, sham operation, and control. The PCR gene chip was used to study gene expression changes. BDNF lentivirus transfection was used for BDNF overexpression. A heroin CPP model and a naloxone withdrawal model of rats were established.ResultsExpression changes were found in 20 of the 84 DA-associated genes in the NAc of heroin-addicted rats. Weight loss and withdrawal symptoms in the lentivirus group for naloxone withdrawal was less than in the blank virus and the sham operation group. These 2 latter groups also showed significant behavioral changes, but such changes were not observed in the BDNF lentivirus group before or after training. DRD3 and DAT increased in the NAc of the lentivirus group.ConclusionsBDNF and DA in the NAc are involved in heroin addiction. BDNF overexpression in NAc reduces withdrawal symptoms and craving behavior for medicine induced by environmental cues for heroin-addicted rats. BDNF participates in the regulation of the dopamine system by acting on DRD3 and DAT.

Brain derived neurotrophic factor (BDNF) is an important modulator of neuronal function, capable of mediating long‐term changes in neuronal structure and signaling in the central nervous system (CNS). Increased expression of BDNF in the PVN has been associated with elevated blood pressure (BP) and sympathetic nervous system activity. However, the mechanism mediating this effect of BDNF is unclear. BDNF is a modulator of catecholaminergic (CA‐ergic) neuronal function in the CNS, and could potentially influence CA‐ergic input to the PVN. The majority of CA‐ergic projections to the PVN come from the nucleus of the solitary tract (NTS), and these projections have been shown to exert a hypotensive effect. Here, we tested the hypothesis that increased BDNF expression in the PVN elevates BP in part by diminishing the inhibitory input from NTS CA‐ergic neurons projecting to the PVN by downregulating β‐receptors in the PVN. Sprague‐Dawley (SD) rats received bilateral PVN injections of AAV2 viral vectors expressing either green fluorescent protein (GFP) or BDNF and bilateral NTS injections of phosphate‐buffered saline (PBS) or anti‐dopamine‐β‐hydroxylase‐conjugated saporin (DSAP), a neurotoxin selective to noradrenaline‐ and adrenaline‐synthesizing neurons. BDNF overexpression in the PVN without lesioning NTS CAergic neurons significantly increased mean arterial pressure (MAP) (BDNF+PBS: 115±3 mmHg, p<0.01 vs GFP+PBS: 96±2 mmHg). DSAP treatment increased MAP in the GFP group by ~13 mmHg, whereas DSAP treatment in the BDNF group did not significantly alter MAP. This suggests that BDNF overexpression in the PVN may interfere with CA‐ergic communication between the NTS and PVN. Since previous reports suggested that adrenergic β‐receptors exert an inhibitory effect on PVN neurons and lower BP, we tested whether BDNF overexpression in the PVN diminishes hypotensive effects of β‐receptor activation in the PVN. SD rats received bilateral PVN injections of AAV2 viral vectors expressing either GFP or BDNF. Three weeks later, BP responses to an injection of Isoprenaline (125 μM or 250 μM), a non‐selective β‐adrenergic agonist, into the PVN were recorded under alpha chloralosed‐urethane anesthesia. Our results showed that BDNF treatment significantly attenuated MAP responses to Isoprenaline compared to the GFP group in a dose dependent manner. In the GFP group, peak decrease in MAP in response to 125 μM and 250 μM Iso was −21±4 mmHg and −29±4 mmHg, compared with −4±1 mmHg (p<0.01) and −8±1 mmHg (p<0.001) in the BDNF group. To test if the reduced effect of Isoprenaline is due to a BDNF‐induced change in adrenergic receptor expression in the PVN, we assessed adrenergic receptor expression using quantitative RT‐PCR in PVN brain punches from SD rats previously injected with an AAV2 viral vectors expressing either GFP or BDNF. BDNF treatment significantly reduced the expression of β1 adrenergic receptor mRNA expression, whereas α1a, α1b, α2a, and β2 adrenergic receptors were unaffected by BDNF treatment. In summary, our findings indicate that increased BDNF expression in the PVN may disrupt CA‐ergic signaling between the NTS and PVN by downregulating β‐receptors in the PVN.Support or Funding InformationSupported by R01 HL133211‐01A1, AHA 11SDG7560022, and UVM start‐up funds.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Hypoxia causes depression of synaptic plasticity, hyperexcitation of neuronal networks, and the death of specific populations of neurons. However, brief episodes of hypoxia can promote the adaptation of cells. Hypoxic preconditioning is well manifested in glutamatergic neurons, while this adaptive mechanism is virtually suppressed in GABAergic neurons. Here, we show that brain-derived neurotrophic factor (BDNF) overexpression in neurons enhances the preconditioning effect of brief episodes of hypoxia. The amplitudes of the NMDAR- and AMPAR-mediated Ca2+ responses of glutamatergic and GABAergic neurons gradually decreased after repetitive brief hypoxia/reoxygenation cycles in cell cultures transduced with the (AAV)-Syn-BDNF-EGFP virus construct. In contrast, the amplitudes of the responses of GABAergic neurons increased in non-transduced cultures after preconditioning. The decrease of the amplitudes in GABAergic neurons indicated the activation of mechanisms of hypoxic preconditioning. Preconditioning suppressed apoptotic or necrotic cell death. This effect was most pronounced in cultures with BDNF overexpression. Knockdown of BDNF abolished the effect of preconditioning and promoted the death of GABAergic neurons. Moreover, the expression of the anti-apoptotic genes Stat3, Socs3, and Bcl-xl substantially increased 24 h after hypoxic episodes in the transduced cultures compared to controls. The expression of genes encoding the pro-inflammatory cytokines IL-10 and IL-6 also increased. In turn, the expression of pro-apoptotic (Bax, Casp-3, and Fas) and pro-inflammatory (IL-1β and TNFα) genes decreased after hypoxic episodes in cultures with BDNF overexpression. Inhibition of vesicular BDNF release abolished its protective action targeting inhibition of the oxygen-glucose deprivation (OGD)-induced [Ca2+]i increase in GABAergic and glutamatergic neurons, thus promoting their death. Bafilomycin A1, Brefeldin A, and tetanus toxin suppressed vesicular release (including BDNF) and shifted the gene expression profile towards excitotoxicity, inflammation, and apoptosis. These inhibitors of vesicular release abolished the protective effects of hypoxic preconditioning in glutamatergic neurons 24 h after hypoxia/reoxygenation cycles. This finding indicates a significant contribution of vesicular BDNF release to the development of the mechanisms of hypoxic preconditioning. Thus, our results demonstrate that BDNF plays a pivotal role in the activation and enhancement of the preconditioning effect of brief episodes of hypoxia and promotes tolerance of the most vulnerable populations of GABAergic neurons to hypoxia/ischemia.

Intravitreal delivery of brain-derived neurotrophic factor (BDNF) by injection of recombinant protein or by gene therapy can alleviate retinal ganglion cell (RGC) loss after optic nerve injury (ONI) or laser-induced ocular hypertension (OHT). In models of glaucoma, BDNF therapy can delay or halt RGCs loss, but this protection is time-limited. The decreased efficacy of BDNF supplementation has been in part attributed to BDNF TrkB receptor downregulation. However, whether BDNF overexpression causes TrkB downregulation, impairing long-term BDNF signaling in the retina, has not been conclusively proven. After ONI or OHT, when increased retinal BDNF was detected, a concomitant increase, no change or a decrease in TrkB was reported. We examined quantitatively the retinal concentrations of the TrkB protein in relation to BDNF, in a course of adeno-associated viral vector gene therapy (AAV2-BDNF), using a microbead trabecular occlusion model of glaucoma. We show that unilateral glaucoma, with intraocular pressure ( IOP) increased for five weeks, leads to a bilateral decrease of BDNF in the retina at six weeks, accompanied by up to four-fold TrkB upregulation, while a moderate BDNF overexpression in a glaucomatous eye triggers changes that restore normal TrkB concentrations, driving signaling towards long-term RGCs neuroprotection. We conclude that for glaucoma therapy, the careful selection of the appropriate BDNF concentration is the main factor securing the long-term responsiveness of RGCs and the maintenance of normal TrkB levels.

Objective To investigate the effect of mesenchymal stem cells (MSCs) on the neurological function of rats with traumatic brain injury, and to investigate the mechanism of the effect of MSCs. Methods 60 SD rats models with brain injury established by the modified Feeney method were divided into model group, MSCs group and phosphate buffer (PBS) group by. Another 20 healthy SD rats were chosen as the control group. Rats of MSCs group were transplantated with Umbilical cord mesenchymal stem cells isolated and cultured in vitro. Neurological function of rats in each group were evaluated by improved neurological function score (mNSS) standard at 1, 3, 7, 14, 21, 28 d after transplantation. Neuronal nuclear antigen (NeuN) expression level in the brain tissue of rats was detected with immunohistochemical method. Brain-derived neurotrophic factor (BDNF) mRNA level of in the brain tissue of rats was detected with reverse transcriptase-polymerase chain reaction (RT-PCR) method. The apoptosis level of cerebral tissue cells in rats was detected by TdT-mediated dUTP nick end labeling (TUNEL) method. Results Compared with the control group, mNSS score of rats in model group, MSCs group and PBS group increased, NeuN expression decreased increased (P=0.000). Compared with the model group and PBS group, mNSS score of rats in MSCs group significantly decreased, NeuN expression significantly decreased(P=0.000). Compared with the control group BDNF mRNA level (0.31±0.12), BDNF mRNA level in model group, PBS group and MSCs Group (1.32±0.34, 1.23±0.30, 0.81±0.21) significantly increased (P=0.000). Compared with model group and PBS group, the levels of BDNF mRNA in MSCs group significantly reduced (P=0.014, P=0.019). Compared with the apoptosis level of brain tissue in control group (3.14±1.12), apoptosis level in model group, PBS group and MSCs group (27.84±4.32, 25.35±4.89, 10.33±3.32) significantly increased (P=0.000). Compared with model group and PBS group, the level of apoptosis in brain tissue of MSCs group significantly decreased (P=0.000). Conclusion Mesenchymal stem cells can decreased the apoptosis level of brain injury in rats through the mechanism of repairing damaged neurons and promoting the BDNF secretion. It can promote the repair effect on neural function of rats with traumatic brain injury. Key words: Brain injury; Mesenchymal stem cells; Nerve function

We recently showed that striatal overexpression of brain derived neurotrophic factor (BDNF) by adeno-associated viral (AAV) vector exacerbated L-DOPA-induced dyskinesia (LID) in 6-OHDA-lesioned rats. An extensive sprouting of striatal serotonergic terminals accompanied this effect, accounting for the increased susceptibility to LID. We set to investigate whether the BDNF effect was restricted to LID, or extended to dyskinesia induced by direct D1 receptor agonists. Unilaterally 6-OHDA-lesioned rats received a striatal injection of an AAV vector to induce BDNF or GFP overexpression. Eight weeks later, animals received daily treatments with a low dose of SKF82958 (0.02 mg/kg s.c.) and development of dyskinesia was evaluated. At the end of the experiment, D1 and D3 receptors expression levels and D1 receptor-dependent signaling pathways were measured in the striatum. BDNF overexpression induced significant worsening of dyskinesia induced by SKF82958 compared to the GFP group and increased the expression of D3 receptor at striatal level, even in absence of pharmacological treatment; by contrast, D1 receptor levels were not affected. In BDNF-overexpressing striata, SKF82958 administration resulted in increased levels of D1-D3 receptors co-immunoprecipitation and increased phosphorylation levels of Thr34 DARPP-32 and ERK1/2. Here we provide evidence for a functional link between BDNF, D3 receptors and D1-D3 receptor close interaction in the augmented susceptibility to dyskinesia in 6-OHDA-lesioned rats. We suggest that D1-D3 receptors interaction may be instrumental in driving the molecular alterations underlying the appearance of dyskinesia; its disruption may be a therapeutic strategy for treating dyskinesia in PD patients.

A Role for Retinal Brain-Derived Neurotrophic Factor in Ocular Dominance Plasticity

Brain-derived neurotrophic factor (BDNF) plays an essential regulatory role in the survival and differentiation of various neural cell types during brain development and after injury. In this study, we used neural stem cells (NSCs) genetically modified to encode BDNF gene (BDNF/NSCs) and naive NSCs transplantation and found that BDNF/NSCs significantly improved neurological motor function following traumatic brain injury (TBI) on selected behavioral tests. Our data clearly demonstrate that the transplantation of BDNF/NSCs causes overexpression of BDNF in the brains of TBI rats. The number of surviving engrafted cells and the proportion of engrafted cells with a neuronal phenotype were significantly greater in BDNF/NSCs than in naive NSCs-transplanted rats. The expression of pre- and post-synaptic proteins and a regeneration-associated gene in the BDNF/NSCs-transplanted rats was significantly increased compared to that in NSCs-transplanted rats, especially at the early stage of post-transplantation. These data suggest that neurite growth and overexpression of synaptic proteins in BDNF/NSCs-transplanted rats are associated with the overexpression of BDNF, which is hypothesized to be one of the mechanisms underlying the improved functional recovery in motor behavior at the early stage of cell transplantation following TBI. Therefore, the protective effect of the BDNF-modified NSCs transplantation is greater than that of the naive NSCs transplantation.

Alterations in BDNF and NT-3 mRNAs in rat hippocampus after experimental brain trauma.

The number of FDA-approved protein drugs (biologics), such as antibodies, antibody-drug conjugates, hormones, and enzymes, continues to grow at a rapid rate; most of these drugs are used to treat diseases of the peripheral body. Unfortunately, most of these biologics cannot be used to treat brain diseases such as Alzheimer's disease (AD), multiple sclerosis (MS), and brain tumors in a noninvasive manner due to their inability to permeate the blood-brain barrier (BBB). Therefore, there is a need to develop an effective method to deliver protein drugs into the brain. Here, we report a proof of concept to deliver a recombinant brain-derived neurotrophic factor (BDNF) to the brains of healthy and experimental autoimmune encephalomyelitis (EAE) mice via intravenous (iv) injections by co-administering BDNF with a BBB modulator (BBBM) peptide ADTC5. Western blot evaluations indicated that ADTC5 enhanced the brain delivery of BDNF in healthy SJL/elite mice compared to BDNF alone and triggered the phosphorylation of TrkB receptors in the brain. The EAE mice treated with BDNF + ADTC5 suppressed EAE relapse compared to those treated with BDNF alone, ADTC5 alone, or vehicle. We further demonstrated that brain delivery of BDNF induced neuroregeneration via visible activation of oligodendrocytes, remyelination, and ARC and EGR1 mRNA transcript upregulation. In summary, we have demonstrated that ADTC5 peptide modulates the BBB to permit noninvasive delivery of BDNF to exert its neuroregeneration activity in the brains of EAE mice.

Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by an abnormal expansion of CAG repeats in the Ataxin1 (ATXN1) gene. SCA1 is characterized by motor deficits, cerebellar neurodegeneration, and gliosis and gene expression changes. Expression of brain-derived neurotrophic factor (BDNF), growth factor important for the survival and function of cerebellar neurons, is decreased in ATXN1[82Q] mice, the Purkinje neuron specific transgenic mouse model of SCA1. As this decrease in BDNF expression may contribute to cerebellar neurodegeneration, we tested whether delivery of extrinsic human BDNF via osmotic ALZET pumps has a beneficial effect on disease severity in this mouse model of SCA1. Additionally, to test the effects of BDNF on established and progressing cerebellar pathogenesis and motor deficits, we delivered BDNF post-symptomatically. We have found that post-symptomatic delivery of extrinsic BDNF ameliorated motor deficits and cerebellar pathology (i.e., dendritic atrophy of Purkinje cells, and astrogliosis) indicating therapeutic potential of BDNF even after the onset of symptoms in SCA1. However, BDNF did not alter Purkinje cell gene expression changes indicating that certain aspects of disease pathogenesis cannot be ameliorated/slowed down with BDNF and that combinational therapies may be needed.

An AMPA receptor potentiator modulates hippocampal expression of BDNF: an in vivo study

Brain-derived neurotrophic factor (BDNF) and NGF are both expressed by neurons in the hippocampus. In previous studies, it has been demonstrated that both BDNF and NGF mRNA levels are regulated by neuronal activity. Upregulation is predominantly regulated by the glutamate (NMDA and non-NMDA receptors); downregulation, predominantly by the GABA system (Zafra et al., 1990, 1991). In neuronal cultures of the rat hippocampus, potassium depolarization and kainic acid-mediated increases in BDNF and NGF mRNA were eliminated in a dose-dependent manner by the calcium channel blocker nifedipine. Conversely, calcium ionophores (Bay-K8644 and ionomycin) augmented BDNF and NGF mRNA levels by a calmodulin-mediated mechanism. In view of the fact that many potential modulators (conventional transmitters and neuropeptides) of neuronal and astrocytic BDNF and NGF mRNA synthesis may act via the adenylate cyclase system, we studied the effect of forskolin, an activator of adenylate cyclase. Indeed, forskolin enhanced the effects of calcium ionophores and kainic acid on BDNF and NGF mRNA levels. Cytokines, such as interleukin-1 and transforming growth factor-beta 1, which have previously been shown to increase NGF mRNA markedly in astrocytes, were without effect on neuronal BDNF and NGF mRNA levels. In contrast to neuronal cultures, where the regulation of BDNF and NGF mRNA was generally very similar, the regulation in astrocytes was distinctly different. All the cytokines that produce a marked increase in NGF mRNA were without effect on astrocyte BDNF mRNA levels, which under basic conditions were below the detection limit. However, norepinephrine produced a marked elevation of BDNF mRNA in astrocytes, an effect that was further enhanced by glutamate receptor agonists.(ABSTRACT TRUNCATED AT 250 WORDS)