Brain-derived Neurotrophic Factor Protein Expression Research Articles

Asiaticoside improves depressive-like behavior in mice with chronic unpredictable mild stress through modulation of the gut microbiota.

Asiaticoside, the main active ingredient of Centella asiatica, is a pentacyclic triterpenoid compound. Previous studies have suggested that asiaticoside possesses neuroprotective and anti-depressive properties, however, the mechanism of its anti-depressant action not fully understood. In recent years, a growing body of research on anti-depressants has focused on the microbiota-gut-brain axis, we noted that disruption of the gut microbial community structure and diversity can induce or exacerbate depression, which plays a key role in the regulation of depression. Behavioral experiments were conducted to detect depression-like behavior in mice through sucrose preference, forced swimming, and open field tests. Additionally, gut microbial composition and short-chain fatty acid (SCFA) levels in mouse feces were analyzed 16S rRNA sequencing and gas chromatography-mass spectrometry (GC-MS). Hippocampal brain-derived neurotrophic factor (BDNF) and 5-hydroxytryptamine receptor 1A (5-HT1A) expression in mice was assessed by western blotting. Changes in serum levels of inflammatory factors, neurotransmitters, and hormones were measured in mice using ELISA. This study revealed that oral administration of asiaticoside significantly improved depression-like behavior in chronic unpredictable mild stress (CUMS) mice. It partially restored the gut microbial community structure in CUMS mice, altered SCFA metabolism, regulated the hypothalamic-pituitary-adrenal axis (HPA axis) and inflammatory factor levels, upregulated BDNF and 5-HT1A receptor protein expression, and increased serum serotonin (5-hydroxytryptamine, 5-HT) concentration. These findings reveal that asiaticoside exerts antidepressant effects via the microbiota-gut-brain axis. These results suggested that asiaticoside exerts antidepressant effects through the microbiota-gut-brain axis in a CUMS mouse model.

Working Memory Performance Predicts, but Does Not Reduce, Cocaine and Cannabinoid Seeking in Adult Male Rats.

Cognitive deficits reflecting impaired executive function are commonly associated with psychiatric disorders, including substance use. Cognitive training is proposed to improve treatment outcomes for these disorders by promoting neuroplasticity within the prefrontal cortex, enhancing executive control, and mitigating cognitive decline due to drug use. Additionally, brain derived neurotrophic factor (BDNF) can facilitate plasticity in the prefrontal cortex and reduce drug-seeking behaviors. We investigated whether working memory training could elevate BDNF levels in the prefrontal cortex and if this training would predict or protect against cocaine or cannabinoid seeking. Adult male rats were trained to perform a "simple" or "complex" version of a delayed-match-to-sample working memory task. Rats then self-administered cocaine or the synthetic cannabinoid WIN55,212-2 and were tested for cued drug seeking during abstinence. Tissue from the prefrontal cortex and dorsal hippocampus was analyzed for BDNF protein expression. Training on the working memory task enhanced endogenous BDNF protein levels in the prelimbic prefrontal cortex but not the dorsal hippocampus. Working memory training did not impact self-administration of either drug but predicted the extent of WIN self-administration and cocaine seeking during abstinence. These results suggest that working memory training promotes endogenous BDNF but does not alter drug-seeking or drug-taking behavior. However, individual differences in cognitive performance before drug exposure may predict vulnerability to future drug use.

Effects and mechanisms of electroacupuncture on fear extinction and sleep phase in single prolonged stress mice

To observe the effects of electroacupuncture (EA) on fear extinction and sleep phase in single prolonged stress (SPS) mice, and explore its mechanism in view of the expression of relevant synaptic proteins. Thirty-two C57BL/6J male mice were randomly divided into a control group, a model group, an EA group and a paroxetine (PRX) group, with 8 mice in each one. Modified SPS method was used to establish PTSD model in the model group, the EA group and the PRX group. Seven days after modeling completion, in the EA group, the intervention was delivered at "Baihui" (GV 20) and bilateral "Zusanli" (ST 36), with disperse-dense wave, 3 Hz/15 Hz in frequency and 1 mA in current intensity, for 30 min. In the PRX group, paroxetine solution (2.5 g/L) was administered intragastrically (10 mg/kg). The intervention was given once daily and for consecutive 10 days in the above two groups. The fear conditioning task and the elevated plus-maze test were adopted to evaluate the fear extinction and anxiety of the mice in each group. Using Medusa electroencephalogram (EEG) and electromyography (EMG) recording system from rats and mice, the sleep phase was determined in the mice. With Western blot method adopted, the protein expression of the postsynaptic density protein 95 (PSD95), activity-regulated cytoskeleton-associated protein (ARC), brain-derived neurotrophic factor (BDNF), N-methyl-D-aspartic acid receptor 2A (GluN2A), N-methyl-D-aspartic acid receptor 2B (GluN2B) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor 1 (GluA1) in the hippocampus was detected in the mice. Compared with the control group, the freezing time for the fear re-exposure in 3 min to 15 min and the fear extinction in 0 min to 3 min were prolonged (P<0.05), the fear extinction index decreased (P<0.05), and the open arm time (OT) of the elevated plus-maze was shortened (P<0.05) in the model group. When compared with the model group, in the EA group and the PRX group, the freezing time for the fear re-exposure in 3 min to 6 min and 12 min to 15 min, as well as the fear extinction in 0 min to 3 min was shortened (P<0.05), the fear extinction index increased (P<0.05); the OT in elevated plus-maze was longer in the mice of the EA group (P<0.05). The period of wake (Wake) was prolonged (P<0.05), the non-rapid eye movement period (NREM) and the total sleep time (Sleep) were reduced in the model group (P<0.05) in comparison with the control group. Compared with the model group, the Wake was declined (P<0.05), and the NREM and Sleep increased in the EA group and the PRX group (P<0.05). When compared with the control group, the protein expression of PSD95, ARC, BDNF, GluN2A and GluA1 in the hippocampus decreased (P<0.05), and that of GluN2B increased (P<0.05) in the model group. In the EA group and the PRX group, the protein expression of PSD95, ARC, BDNF, GluN2A and GluA1 in the hippocampus was elevated (P<0.05), and that of GluN2B reduced (P<0.05) when compared with the model group. Electroacupuncture at "Baihui" (GV 29) and "Zusanli" (ST 36) can ameliorate anxiety-like behavior, fear extinction disorder and abnormal sleep phase in SPS mice, which may be related to the regulation of synaptic transmission and synaptic plasticity expression in the hippocampus.

Regional-specific changes in rat brain BDNF in a model of methamphetamine abuse

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, plays key roles in neuronal protection and synaptic plasticity. Changes in BDNF are associated with various pathological conditions, including methamphetamine (meth) addiction, although the effects of meth on BDNF expression are not always consistent. We have previously demonstrated region-specific effects of a chronic meth regime on BDNF methylation and expression in the rat brain. This study aims to determine the effect of chronic meth administration on the expression of BDNF protein using immunohistochemistry in the rat frontal cortex and hippocampus. Novel object recognition (NOR) as a measure of cognitive function was also determined. Male Sprague Dawley rats were administered a chronic escalating dose (0.1–4 mg/kg over 14 days) (ED) of meth or vehicle; a subgroup of animals receiving meth were also given an acute “binge” (4x6mg) dose on the final day before NOR testing. The results showed that hippocampal CA1 BDNF protein was significantly increased by 72 % above control values in the ED-binge rats, while other hippocampal regions and frontal cortex were not significantly affected. Meth-administered animals also demonstrated deficits in NOR after 24 h delay. No significant effect of the additional binge dose on BDNF protein or NOR findings was apparent. This finding is consistent with our previous results of reduced DNA methylation and increased expression of the BDNF gene in this region. The hippocampal BDNF increase may reflect an initial increase in a protective factor produced in response to elevated glutamate release resulting in neurodegenerative excitotoxicity.

Working memory performance predicts, but does not reduce, cocaine- and cannabinoid-seeking in adult male rats.

Cognitive deficits reflecting impaired executive function are commonly associated with psychiatric disorders, including substance use. Cognitive training is proposed to improve treatment outcomes for these disorders by promoting neuroplasticity within the prefrontal cortex, enhancing executive control, and mitigating cognitive decline due to drug use. Additionally, brain derived neurotrophic factor (BDNF) can facilitate plasticity in the prefrontal cortex and reduce drug-seeking behaviors. We investigated whether working memory training could elevate BDNF levels in the prefrontal cortex and if this training would predict or protect against cocaine or cannabinoid seeking. Adult male rats were trained to perform a 'simple' or 'complex' version of a delayed- match-to-sample working memory task. Rats then self-administered cocaine or the synthetic cannabinoid WIN55,212-2 and were tested for cued drug-seeking during abstinence. Tissue from the prefrontal cortex and dorsal hippocampus was analyzed for BDNF protein expression. Training on the working memory task enhanced endogenous BDNF protein levels in the prelimbic prefrontal cortex but not the dorsal hippocampus. Working memory training did not impact self-administration of either drug but predicted the extent of WIN self-administration and cocaine seeking during abstinence. These results suggest that working memory training promotes endogenous BDNF but does not alter drug-seeking or drug-taking behavior. However, individual differences in cognitive performance prior to drug exposure may predict vulnerability to future drug use.

Improving dietary patterns in obese mice: Effects on body weight, adiposity, anhedonia-like behavior, pro-BDNF expression and 5-HT system

IntroductionThe excessive fat accumulation in obesity, resulting from an unbalanced diet, can lead to metabolic and neurological disorders and increase the risk of developing anxiety and depression. AimAssess the impact of dietary intervention (DI) on the serotonergic system, brain-derived neurotrophic factor (BDNF) expression and behaviors of obese mice. MethodsMale C57BL/6 mice, 5 weeks old, received a high-fat diet (HFD) for 10 weeks for the induction of obesity. After this period, for 8 weeks, half of these animals received a control diet (CD), group obese (OB) + control diet (OB + CD, n = 10), and another half continued being fed HFD, group obese + HFD (OB + HFD, n = 10). At the end of the eighth week of intervention, behavioral tests were performed (sucrose preference test, open field, novel object recognition, elevated plus maze and tail suspension). Body weight and food intake were assessed weekly. Visceral adiposity, the hippocampal and hypothalamic protein expression of BDNF, 5-HT1A (5-HT1A serotonin receptor) and TPH2 (key enzyme in serotonin synthesis), were evaluated after euthanasia. ResultsThe dietary intervention involved changing from a HFD to a CD over an 8-week period, effectively reduced body weight gain, adiposity, and anhedonia-like behavior. In the OB + HFD group, we saw a lower sucrose preference and shorter traveled distance in the open field, along with increased pro-BDNF expression in the hypothalamus compared to the OB + CD mice. However, the levels of TPH2 and 5-HT1A remained unchanged. ConclusionThe HFD model induced both obesity and anhedonia, but the dietary intervention successfully improved these conditions.

Brain Derived Neurotrophic Factor (BDNF) Immunolabeling in C4-C5 Spinal Cord of Adult Female Rats Following Acute Intermittent Hypoxia (AIH) Exposure Composed of 5,3-min Hypoxic Episodes (AIH5x3min) at 4-weeks After mid-thoracic SCI

Acute intermittent hypoxia (AIH) induces spinal neural plasticity in both respiratory and non-respiratory somatic motor systems. AIH-induced neural plasticity has been best studied in the respiratory neural control system, where exposure to moderate AIH (9-15% inspired O2), typically composed of 3,5-min hypoxic episodes (AIH3x5min), has been shown to consistently elicit a robust increase in phrenic motor activity due to a serotonin-dependent mechanism that promotes de novo synthesis of BDNF and activation of high affnity BDNF-TrkB receptors to initiate ERK MAP kinase signaling in phrenic motoneurons. Whether other protocols that use a total duration of 15 min of hypoxic exposure, but with an increased number of shorter duration hypoxic episodes ( e.g, AIH5x3min) similarly elicit serotonin-dependent BDNF pathway-mediated neural plasticity mechanisms in this region remains to be determined. To begin to assess this possibility, we evaluated BDNF expression in C4-C5 spinal cord segments containing the phrenic motor nucleus following single exposure to AIH5x3min (12% O2) in urethane-anesthetized spontaneously breathing adult female rats at 4-weeks after mid-thoracic SCI. Experiments using AIH3x5min (12% O2) exposure and intermittent normoxia (Nx, 21% O2) exposure served as controls. At ~60-90 min after the AIH or Nx exposure protocol, the rats were transcardially perfused with saline followed by 4% PFA, and various regions of the CNS, including the C3-C5 spinal cord were removed, post-fixed, and cryoprotected. 20 μm thick transverse sections were then cut to obtain sets of slides for single- or double-label fluorescence IHC staining to localize BDNF protein expression in the C4-C5 spinal cord, including the region containing the phrenic motor nucleus. Preliminary analyses show that both AIH5x3min and AIH3x5min exposures elicit increased BDNF expression when compared to Nx exposure, with both diffuse cytosolic and punctate immunofluorescence labeling in and around neurons within the phrenic motor nucleus region, including labeling of presumptive phrenic motoneurons. No labeling was seen in adjacent tissue sections that were incubated without the primary antibody. Immunofluorescence labeling was also seen in the more medial regions of lamina VIII in the ventral horn, the medial regions of laminae VI and VII, and throughout lamina X; these regions have been reported to contain the V0-V3 classes of spinal interneurons (SpINs) albeit we did not verify BDNF labeling of specific classes of presumptive SpINs. These preliminary observations suggest that AIH5x3min exposure likely recruits a serotonin-dependent BDNF pathway-mediated mechanism for neural plasticity in a manner similar to that seen for AIH3x5min exposure. APS Summer Undergraduate Research Fellowship; DOD CDMRP W81XWH-17-1-0260; NYS DOH SCIRB C37711GG. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of carbamazepine on BDNF expression in trigeminal ganglia and serum in rats with trigeminal neuralgia.

Trigeminal neuralgia (TN) is a severe chronic neuropathic pain that mainly affects the distribution area of the trigeminal nerve with limited treating efficacy. There are numerous treatments for TN, but currently the main clinical approach is to suppress pain by carbamazepine (CBZ). Brain-derived neurotrophic factor (BDNF) is closely related to chronic pain. This study aims to determine the effects of CBZ treatment on BDNF expression in both the trigeminal ganglion (TG) and serum of TN via a chronic constriction injury of the infraorbital nerve (ION-CCI) rat model. The ION-CCI models were established in male Sprague-Dawley rats and were randomly divided into a sham group, a TN group, a TN+low-dose CBZ treatment group (TN+20 mg/kg CBZ group), a TN+medium-dose CBZ treatment group (TN+40 mg/kg CBZ group), and a TN+high-dose CBZ treatment group (TN+80 mg/kg CBZ group). The mechanical pain threshold in each group of rats was measured regularly before and after surgery. The expressions of BDNF and tyrosine kinase receptor B (TrkB) mRNA in TGs of rats in different groups were determined by real-time PCR, and the expression of BDNF protein on neurons in TGs was observed by immunofluorescence. Western Blotting was used to detect the protein expression of BDNF, TrkB, extracellular regulated protein kinases (ERK), and phospho-extracellular regulated protein kinases (p-ERK) in TGs of rats in different groups. The expression of BDNF in the serum of rats in different groups was detected by enzyme-linked immunosorbent assay (ELISA). The results of mechanical pain sensitivity showed that there was no significant difference in the mechanical pain threshold in the right facial sensory area of the experimental rats in each group before surgery (all P>0.05). From the 3rd day after operation, the mechanical pain threshold of rats in the TN group was significantly lower than that in the sham group (all P<0.01), and the mechanical pain threshold of rats in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 CBZ mg/kg group was higher than that in the TN group (all P<0.05). The BDNF and TrkB mRNA and protein expressions in TGs of rats in the TN group were higher than those in the sham group (all P<0.05), and those in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than the TN group (all P<0.05). The p-ERK levels in TG of rats in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were significantly decreased compared with the TN group (all P<0.05). The BDNF and neuron-specific nuclear protein (NeuN) were mainly co-expressed in neuron of TGs in the TN group and they were significantly higher than those in the sham group (all P<0.05). The co-labeled expressions of BDNF and NeuN in TGs of the TN+ 80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than those in the TN group (all P<0.05). The results of ELISA showed that the level of BDNF in the serum of the TN group was significantly higher than that in the sham group (P<0.05). The levels of BDNF in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than those in the TN group (all P<0.05). Spearman correlation analysis showed that the BDNF level in serum was negatively correlated with mechanical pain threshold (r=-0.650, P<0.01). CBZ treatment can inhibit the expression of BDNF and TrkB in the TGs of TN rats, reduce the level of BDNF in serum of TN rats and the phosphorylation of ERK signaling pathway, so as to inhibit TN. The serum level of BDNF can be considered as an indicator for the diagnosis and prognosis of TN.

Dentate Gyrus Granule Cells Show Stability of BDNF Protein Expression in Mossy Fiber Axons with Age, and Resistance to Alzheimer's Disease Neuropathology in a Mouse Model.

Brain-derived neurotrophic factor (BDNF) is important in the development and maintenance of neurons and their plasticity. Hippocampal BDNF has been implicated in Alzheimer's disease (AD) because hippocampal levels in AD patients and AD animal models are often downregulated, suggesting that reduced BDNF contributes to AD. However, the location where hippocampal BDNF protein is most highly expressed, the mossy fiber (MF) axons of dentate gyrus granule cells (GCs), has been understudied, and not in controlled conditions. Therefore, we evaluated MF BDNF protein in the Tg2576 mouse model of AD. Tg2576 and wild-type (WT) mice of both sexes were examined at 2-3 months of age, when amyloid-β (Aβ) is present in neurons but plaques are absent, and 11-20 months of age, after plaque accumulation. As shown previously, WT mice exhibited high levels of MF BDNF protein. Interestingly, there was no significant decline with age in either the genotype or sex. Notably, MF BDNF protein was correlated with GC ΔFosB, a transcription factor that increases after 1-2 weeks of elevated neuronal activity. We also report the novel finding that Aβ in GCs or the GC layer was minimal even at old ages. The results indicate that MF BDNF is stable in the Tg2576 mouse, and MF BDNF may remain unchanged due to increased GC neuronal activity, since BDNF expression is well known to be activity dependent. The resistance of GCs to long-term Aβ accumulation provides an opportunity to understand how to protect vulnerable neurons from increased Aβ levels and therefore has translational implications.

BDNF-enriched small extracellular vesicles protect against noise-induced hearing loss in mice

Noise-induced hearing loss (NIHL) is one of the most prevalent acquired sensorineural hearing loss etiologies and is characterized by the loss of cochlear hair cells, synapses, and nerve terminals. Currently, there are no agents available for the treatment of NIHL because drug delivery to the inner ear is greatly limited by the blood–labyrinth barrier. In this study, we used mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) as nanoscale vehicles to deliver brain-derived neurotrophic factor (BDNF) and evaluated their protective effects in a mouse model of NIHL. Following intravenous administration, BDNF-loaded sEVs (BDNF-sEVs) efficiently increased the expression of BDNF protein in the cochlea. Systemic application of sEVs and BDNF-sEVs significantly attenuated noise-induced cochlear hair cell loss and NIHL in CBA/J mice. BDNF-sEVs also alleviated noise-induced loss of inner hair cell ribbon synapses and cochlear nerve terminals. In cochlear explants, sEVs and BDNF-sEVs effectively protected hair cells against H2O2-induced cell loss. Additionally, BDNF-sEVs remarkably ameliorated H2O2-induced oxidative stress, cell apoptosis, and cochlear nerve terminal degeneration. Transcriptomic analysis revealed that many mRNAs and miRNAs were involved in the protective actions of BDNF-sEVs against oxidative stress. Collectively, our findings reveal a novel therapeutic strategy of MSC-sEVs-mediated BDNF delivery for the treatment of NIHL.

Role of brain-derived neurotrophic factor in endotoxaemia-induced acute lung injury.

Acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), which is a pulmonary manifestation of a systemic reactive inflammatory syndrome, is a serious disease with high mortality, and sepsis is an important risk factor in the development of ALI. Brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family. It plays an essential role in the regulation of the modification of synaptic efficacy and brain metabolic activity and enhances neuronal survival. However, the role and underlying mechanism of BDNF in sepsis-induced ALI remain unclear. Here, we sought to observe the expression of BDNF in the lung tissues of mice. C57BL/6J mice were divided randomly into two groups: saline (n=4) and lipopolysaccharide (LPS) (n=4). We found that BDNF expression was elevated in the lung tissues of septic mice. Furthermore, we found that BDNF colocalized with aquaporin 5, a marker for type I alveolar epithelial cells, by immunofluorescence staining. In addition, we also found that tropomyosin-related kinase B, the specific receptor of BDNF, colocalized with surfactant protein C, a marker for type II alveolar epithelial cells, by immunofluorescence staining. Finally, the present study indicated that BDNF may alleviate excessive LPS-induced autophagy in alveolar epithelial cells. Overall, we hypothesize that BDNF expression increases in the lung tissues of septic mice as a compensatory mechanism to ameliorate sepsis-induced ALI by inhibiting excessive alveolar epithelial cell autophagy.

Ketamine Produces Antidepressant Effects by Inhibiting Histone Deacetylases and Upregulating Hippocampal Brain-Derived Neurotrophic Factor Levels in a Diisopropyl Fluorophosphate-Based Rat Model of Gulf War Illness.

Approximately one-third of Gulf War veterans suffer from Gulf War Illness (GWI), which encompasses mood disorders and depressive symptoms. Deployment-related exposure to organophosphate compounds has been associated with GWI development. Epigenetic modifications have been reported in GWI veterans. We previously showed that epigenetic histone dysregulations were associated with decreased brain-derived neurotrophic factor (BDNF) expression in a GWI rat model. GWI has no effective therapies. Ketamine (KET) has recently been approved by the Food and Drug Administration for therapy-resistant depression. Interestingly, BDNF upregulation underlies KET's antidepressant effect in GWI-related depression. Here, we investigated whether KET's effect on histone mechanisms signals BDNF upregulations in GWI. Male Sprague-Dawley rats were injected once daily with diisopropyl fluorophosphate (DFP; 0.5 mg/kg, s.c., 5 days). At 6 months following DFP exposure, KET (10 mg/kg, i.p.) was injected, and brains were dissected 24 hours later. Western blotting was used for protein expression, and epigenetic studies used chromatin immunoprecipitation methods. Dil staining was conducted for assessing dendritic spines. Our results indicated that an antidepressant dose of KET inhibited the upregulation of histone deacetylase (HDAC) enzymes in DFP rats. Furthermore, KET restored acetylated histone occupancy at the Bdnf promoter IV and induced BDNF protein expression in DFP rats. Finally, KET treatment also increased the spine density and altered the spine diversity with increased T-type and decreased S-type spines in DFP rats. Given these findings, we propose that KET's actions involve the inhibition of HDAC expression, upregulation of BDNF, and dendritic modifications that together ameliorates the pathologic synaptic plasticity and exerts an antidepressant effect in DFP rats. SIGNIFICANCE STATEMENT: This study offers evidence supporting the involvement of epigenetic histone pathways in the antidepressant effects of ketamine (KET) in a rat model of Gulf War Illness (GWI)-like depression. This effect is achieved through the modulation of histone acetylation at the Bdnf promoter, resulting in elevated brain-derived neurotrophic factor expression and subsequent dendritic remodeling in the hippocampus. These findings underscore the rationale for considering KET as a potential candidate for clinical trials aimed at managing GWI-related depression.

Transcranial photobiomodulation mitigates learning and memory impairments induced by hindlimb unloading in a mouse model of microgravity exposure by suppression of oxidative stress and neuroinflammation signaling pathways

Prolonged microgravity exposure causes cognitive impairment. Evidence shows that oxidative stress and neuroinflammation are involved in the causation. Here, we explore the effectiveness of transcranial near-infrared photobiomodulation (PBM) on cognitive deficits in a mouse model of simulated microgravity.24 adult male C57BL/6 mice were assigned into three groups (8 in each); control, hindlimb unloading (HU), and HU + PBM groups. After surgery to fit the suspension fixing, the animals were housed either in HU cages or in their normal cage for 14 days. The mice in the HU + PBM group received PBM (810 nm laser, 10 Hz, 8 J/cm2) once per day for 14 days. Spatial learning and memory were assessed in the Lashley III maze and hippocampus tissue samples were collected to assess oxidative stress markers and protein expression of brain-derived neurotrophic factor (BDNF), nuclear factor erythroid 2-related factor 2 (Nrf2), Sirtuin 1 (Sirt1), and Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB).Behavioral testing showed that the PBM-treated animals had a shorter latency time to find the target and fewer errors than the HU group. PBM decreased hippocampal lipid peroxidation while increasing antioxidant defense systems (glutathione peroxidase, superoxide dismutase, and total antioxidant capacity) compared to HU mice. PBM increased protein expression of Sirt1, Nrf2, and BDNF while decreasing NF-κB compared to HU mice.Our findings suggested that the protective effect of PBM against HU-induced cognitive impairment involved the activation of the Sirt1/Nrf2 signaling pathway, up-regulation of BDNF, and reduction of neuroinflammation and oxidative stress in the hippocampus.

Revisiting the expression of BDNF and its receptors in mammalian development.

Brain-derived neurotrophic factor (BDNF) promotes the survival and functioning of neurons in the central nervous system and contributes to proper functioning of many non-neural tissues. Although the regulation and role of BDNF have been extensively studied, a rigorous analysis of the expression dynamics of BDNF and its receptors TrkB and p75NTR is lacking. Here, we have analyzed more than 3,600 samples from 18 published RNA sequencing datasets, and used over 17,000 samples from GTEx, and ~ 180 samples from BrainSpan database, to describe the expression of BDNF in the developing mammalian neural and non-neural tissues. We show evolutionarily conserved dynamics and expression patterns of BDNF mRNA and non-conserved alternative 5' exon usage. Finally, we also show increasing BDNF protein levels during murine brain development and BDNF protein expression in several non-neural tissues. In parallel, we describe the spatiotemporal expression pattern of BDNF receptors TrkB and p75NTR in both murines and humans. Collectively, our in-depth analysis of the expression of BDNF and its receptors gives insight into the regulation and signaling of BDNF in the whole organism throughout life.

Essential role of microglia in the fast antidepressant action of ketamine and hypidone hydrochloride (YL-0919).

Introduction: Intracerebral microglia play a vital role in mediating central immune response, neuronal repair and synaptic pruning, but its precise role and mechanism in fast action of antidepressants have remained unknown. In this study, we identified that the microglia contributed to the rapid action of antidepressants ketamine and YL-0919. Methods: The depletion of microglia was achieved with the diet containing the colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 in mice. The tail suspension test (TST), forced swimming test (FST) and novelty suppressed feeding test (NSFT) were employed to evaluate the rapid acting antidepressant behavior of ketamine and YL-0919 in the microglia depletion model. The number of microglia in the prefrontal cortex (PFC) was assayed by the immunofluorescence staining. The expressions of synaptic proteins (synapsin-1, PSD-95, GluA1) and brain-derived neurotrophic factor (BDNF) in the PFC were tested by Western blot. Results: The immobility duration in FST and the latency to feed in NSFT were shortened 24h after an intraperitoneal (i.p.) injection of ketamine (10mg/kg). The microglial depletion of PLX3397 blocked the rapid antidepressant-like effect of ketamine in mice. In addition, the immobility time in TST and FST as well as latency to feed in NSFT were reduced 24h after the intragastric (i.g.) administration of YL-0919 (2.5mg/kg), and the rapid antidepressant effect of YL-0919 was also blocked by the microglial depletion using PLX5622. About 92% of microglia in the prefrontal cortex was depleted in PLX5622 diet-fed mice, while both ketamine and YL-0919 promoted proliferation on the remaining microglia. YL-0919 significantly increased the protein expressions of synapsin-1, PSD-95, GluA1 and BDNF in the PFC, all of which could be blocked by PLX5622. Conclusion: These results suggested the microglia underlying the rapid antidepressant-like effect of ketamine and YL-0919, and microglia would likely constitute in the rapid enhancing impact of synaptic plasticity in the prefrontal cortex by YL-0919.

Effect of electroacupuncture on the expression of Iba-1 in spinal dorsal horn and hippocampus of chronic pain rats with knee osteoarthritis

To observe the effect of electroacupuncture(EA) on pain-ralated behaviors, morphology of hippocampus, concentrations of inflammatory cytokines and expression of ionized calcium binding adapter molecule 1(Iba-1) in dorsal horn of the spinal cord and the hippocampus, and brain-derived neurotrophic factor (BDNF) in hippocampus of rats with knee osteoarthritis (KOA), so as to explore the mechanism of EA in improving chronic pain of KOA. Forty SD rats were randomly divided into blank group, saline group, model group and EA group, with 10 rats in each group. Monosodium iodoacetate(MIA, 80 mg/mL, 50 μL) was injected into the left knee joint cavity of rats in the model group and EA group to establish the chronic pain model of KOA, while the same volume of normal saline was injected into the left knee joint cavity of rats in the saline group. Rats in the EA group received EA stimulation(2 Hz/100 Hz, 1-2 mA) at left "Yanglingquan"(GB34) and "Neixiyan"(EX-LE4) for 15 min, 14 d after MIA injection. The treatment was given once daily, 5 d as 1 session and 2 sessions of treatment were required. Methanical withdrawl threshold(MWT) and weight-bearing capacity tests on left hind limbs were carried out 1 d before, 7 d，14 d, 20 d and 26 d after MIA injection. At the 27th day, rats were sacrificed and HE staining was used to observe the morphology of hippocampal CA1 area. Concentrations of interleukin(IL)-1β and tumor necrosis factor(TNF)-α in the left L3-L5 spinal dorsal horn and hippocampal CA1 area were detected by ELISA, the expressions of Iba-1 in the spinal dorsal horn and hippo-campal CA1 area were detected by immunofluorescence, and the expression of BDNF in left hippocampal CA1 area was detected by Western blot. The HE staining results of the hippocampal CA1 area showed reduced number of neurons, unclear cell contour and boundary between nucleus and cytoplasm, and nuclear pyknosis in the model group, which was relatively milder in the EA group. Compared with the blank group, MWT and weight-bearing capacity of rats' left hind limbs, and expression of BDNF protein in hippocampal CA1 area were significantly decreased (P<0.01), while the contents of IL-1β and TNF-α, the expression of Iba-1 in spinal dorsal horn and hippocampal CA1 area were significantly increased (P<0.01) in the model group. In comparison with the model group, MWT and weight-bearing capacity of rats' left hind limbs, and protein expression of BDNF in hippocampal CA1 area were significantly increased (P<0.01), while the contents of IL-1β and TNF-α, and the expression of Iba-1 protein in spinal dorsal horn and hippocampal CA1 area were significantly decreased after EA intervention(P<0.01). EA at GB34 and EX-LE4 can alleviate the pain-related behaviors of KOA rats. The mechanism might be related to the inhibition of inflammatory reaction mediated by microglia in spinal dorsal horn and hippocampus, and the up-regulation of BDNF expression in hippocampus.

The potential beneficial effects of Lactobacillus plantarum GM11 on rats with chronic unpredictable mild stress- induced depression

ABSTRACT Objective The main purpose of the present study was to assess the beneficial effect of Lactobacillus plantarum GM11 (LacP GM11), screened from Sichuan traditional fermented food, in depressive rats induced by chronic unpredictable mild stress (CUMS). Methods Male SPF SD rats were randomly assigned to 3 groups: the control group, CUMS group and CUMS + LacP GM11 group (n = 10). The rats in the CUMS and LacP GM11 groups received CUMS stimulation for 42 d. The behavioral tests and levels of monoamine neurotransmitter, glucocorticoid hormone and brain-derived neurotrophic factor (BDNF) in the serum and hippocampus were measured. The effects of LacP GM11 on the mRNA and protein expression of BDNF and cAMP response element binding protein (CREB) in the hippocampus were also investigated. Results After supplementation for 21 d, LacP GM11 was associated with alleviation of depressive-like behavior, not anxiety-like behavior, in depressive rats. LacP GM11 increased the levels of 5-hydroxytryptamine (5-HT) and BDNF and decreased the level of cortisol (CORT) in the serum and hippocampus in depressed rats. In addition, treatment with LacP GM11 also increased the mRNA and protein expression of BDNF and CREB in the hippocampus. Conclusions This work has revealed that LacP GM11 has potential beneficial effects on depression. This effect might be related to alleviating monoamine neurotransmitter deficiency, HPA axis hyperfunction and CREB-BDNF signaling pathway downregulation. This study demonstrates that LacP GM11 could be a potential therapeutic approach to treat depression and other mental health problems.

Engineering brain-derived neurotrophic factor mRNA delivery for the treatment of Alzheimer’s disease

Brain-derived neurotrophic factor (BDNF) has a long history in the treatment neurodegenerative of diseases. However, this therapy has limitations in exogenous protein safety, including side effects like neuropathic pain and seizures. Moreover, there are currently no positive clinical trial results using BDNF-based gene therapy. Given this, new methods of delivering BDNF are urgently needed. Here, we report an engineering BDNF mRNA-based therapy in a murine model of Alzheimer’s disease (AD). Two poly (β amino esters) polymers (PBAE) were synthesized, which achieved mRNA delivery to brain and spinal cord efficiently following catheter ventricle pumping. To confer stability and RNase resistance, the secondary structure of the mRNA was engineering using AI algorithms. Further mRNA modification was done on 3′ untranslated region (3′UTR), which was added with neuron-specific miRNA targeting sequence to avoid BDNF protein expression in neuron. This allowed reduced neuronal overexcitation and seizures. And BDNF protein was sustained released from astrocytes to maintain surrounding neural function. The engineering mRNA was delivered into the brain ventricle and translated into astrocytes to significantly improve the memory of AD mice. Given the mRNA modifications presented here, it would de-target delivery to specific cell types and has therapeutic potential for the treatment of neurological diseases.

Antisense oligonucleotides targeting basal forebrain ATXN2 enhances spatial memory and ameliorates sleep deprivation-induced fear memory impairment in mice.

Regulation of brain-derived neurotrophic factor (BDNF) in the basal forebrain ameliorates sleep deprivation-induced fear memory impairments in rodents. Antisense oligonucleotides (ASOs) targeting ATXN2 was a potential therapy for spinocerebellar ataxia, whose pathogenic mechanism associates with reduced BDNF expression. We tested the hypothesis that ASO7 targeting ATXN2 could affect BDNF levels in mouse basal forebrain and ameliorate sleep deprivation-induced fear memory impairments. Adult male C57BL/6 mice were used to evaluate the effects of ASO7 targeting ATXN2 microinjected into the bilateral basal forebrain (1 μg, 0.5 μL, each side) on spatial memory, fear memory and sleep deprivation-induced fear memory impairments. Spatial memory and fear memory were detected by the Morris water maze and step-down inhibitory avoidance test, respectively. Immunohistochemistry, RT-PCR, and Western blot were used to evaluate the changes of levels of BDNF, ATXN2, and postsynaptic density 95 (PSD95) protein as well as ATXN2 mRNA. The morphological changes in neurons in the hippocampal CA1 region were detected by HE staining and Nissl staining. ASO7 targeting ATXN2 microinjected into the basal forebrain could suppress ATXN2 mRNA and protein expression for more than 1 month and enhance spatial memory but not fear memory in mice. BDNF mRNA and protein expression in basal forebrain and hippocampus was increased by ASO7. Moreover, PSD95 expression and synapse formation were increased in the hippocampus. Furthermore, ASO7 microinjected into the basal forebrain increased BDNF and PSD95 protein expression in the basal forebrain of sleep-deprived mice and counteracted sleep deprivation-induced fear memory impairments. ASOs targeting ATXN2 may provide effective interventions for sleep deprivation-induced cognitive impairments.

Moderate-Intensity Intermittent Training Alters the DNA Methylation Pattern of PDE4D Gene in Hippocampus to Improve the Ability of Spatial Learning and Memory in Aging Rats Reduced by D-Galactose

(1) Background: Aging is the main risk factor for most neurodegenerative diseases, and the inhibition of Phosphodiesterase 4(PDE4) is considered a potential target for the treatment of neurological diseases. The purpose of this study was to investigate the inhibitory effect of moderate-intensity intermittent training (MIIT) on PDE4 in the hippocampus of rats with D-galactose (D-gal)-induced cognitive impairment, and the possible mechanism of improving spatial learning and memory. (2) Methods: the aging rats were treated with D-Gal (150 mg/kg/day, for 6 weeks). The aging rats were treated with MIIT for exercise intervention (45 min/day, 5 days/week, for 8 weeks). The Morris water maze test was performed before and after MIIT to evaluate the spatial learning and memory ability, then to observe the synaptic ultrastructure of the hippocampus CA1 region, to detect the expression of synaptic-related protein synaptophysin (SYP) and postsynaptic density protein 95 (PSD95), and to detect the expression of PDE4 subtypes, cAMP, and its signal pathway protein kinase A (PKA)/cAMP response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF), and the PDE4 methylation level. (3) Results: we found that MIIT for 8 weeks alleviated the decline in spatial learning and memory ability, and improved the synaptic structure of the hippocampus and the expression of synaptic protein SYP and PSD95 in D-Gal aging rats. To elucidate the mechanism of MIIT, we analyzed the expression of PDE4 isoforms PDE4A/PDE4B/PDE4D, cAMP, and the signaling pathway PKA/CREB/BDNF, which play an important role in memory consolidation and maintenance. The results showed that 8 weeks of MIIT significantly up-regulated cAMP, PKA, p-CREB, and BDNF protein expression, and down-regulated PDE4D mRNA and protein expression. Methylation analysis of the PDE4D gene showed that several CG sites in the promoter and exon1 regions were significantly up-regulated. (4) Conclusions: MIIT can improve the synaptic structure of the hippocampus CA1 area and improve the spatial learning and memory ability of aging rats, which may be related to the specific regulation of the PDE4D gene methylation level and inhibition of PDE4D expression.