Antidepressant-like Effect of 3-n-Butylphthalide in Rats Exposed to Chronic Unpredictable Mild Stress: Modulation of Brain-Derived Neurotrophic Factor Level and mTOR Activation in Cortex.

3-n-Butylphthalide (NBP), an extract from seeds of Apium graveolens Linn. (Chinese celery), has been demonstrated to have antidepressant effects in suspension chronic-stressed rats by our group. The purpose of this study was to investigate the possible involvement of brain-derived neurotrophic factor (BDNF) and mammalian target of rapamycin (mTOR) in the antidepressant mechanism of NBP. Chronic unpredictable mild stress (CUMS) was applied for 6 weeks to induced a depressive-like behavior, characterized by decreased locomotor activity, sucrose preference and the NE, DA and 5-HT levels in cortex. Oral treatment with NBP (30 or 100 mg/kg, p.o.), similarly to fluoxetine (2 mg/kg, p.o.), can prevention of these alterations. The NBP (30 or 100 mg/kg, p.o.) reversed the decrease in the BDNF, p-ERK, mTOR and synapsin-1 protein levels in rat cortex caused by CUMS. And rapamycin, an mTOR inhibitor, completely inhibited the antidepressant-like activity of NBP in vivo. In conclusion, these findings indicate that NBP treatment attenuated the depression-like behaviors through the modulation of serotonergic system and BDNF-ERK-mTOR signaling in rat.

Brain-derived neurotrophic factor upregulates synaptic GluA1 in the amygdala to promote depression in response to psychological stress.

Psychological stress impairs neuronal structure and function and leads to emotional disorders, but the underlying mechanisms have not yet been fully elucidated. The amygdala is closely correlated with emotional regulation. In the present study, we analyzed whether the amygdala plasticity is regulated by psychological stress and explored their regulatory mechanism. We established a mouse psychological stress model using an improved communication box, wherein mice were exposed to chronic fear and avoided physical stress interference. After the 14-day psychological stress paradigm, mice exhibited significantly increased depressive behaviors (decreased sucrose consumption in the sucrose preference test and longer immobility time in the forced swimming test). HPLC, ELISA, and molecular and morphological evidences showed that psychological stress increased the content of glutamate and the expression of glutamatergic neurons, upregulated the content of the stress hormone corticosterone, and activated the CREB/BDNF pathway in the amygdala. Furthermore, psychological stress induced an increased density of dendritic spines and LTD impairment in the amygdala. Importantly, virus-mediated silencing of BDNF in the basolateral amygdala (BLA) nuclei reversed the depression-like behaviors and the increase of synaptic GluA1 and its phosphorylation at Ser831 and Ser845 sites in psychologically stressed mice. This process was likely achieved through mTOR signaling activation. Finally, we treated primary amygdala neurons with corticosterone to mimic psychological stress; corticosterone-induced upregulation of GluA1 was prevented by BDNF and mTOR antagonists. Thus, activation of the CREB/BDNF pathway in the amygdala following psychological stress upregulates synaptic GluA1 via mTOR signaling, which dysregulates synaptic plasticity of the amygdala, eventually promoting depression.

Osmotic core-shell polymeric implant for sustained BDNF AntagoNAT delivery in CNS using minimally invasive nasal depot (MIND) approach.

The development of drug delivery strategies for efficacious therapeutic administration directly into the central nervous system (CNS) in a minimally invasive manner remains a major obstacle hindering the clinical translation of biological disease-modifying therapeutics. A novel direct trans-nasal delivery method, termed 'Minimally-Invasive Nasal Depot' (MIND), has proved to be successful in providing high CNS uptake and brain distribution of blood-brain barrier (BBB) impermeant therapeutics via direct administration to the olfactory submucosal space in a rodent model. The present study describes the engineering of custom-made implants with a unique architecture of an "osmotically-active core" entrapping the therapeutic and a "biodegradable polymeric shell" to enable long-acting delivery using the MIND procedure. The MIND-administered implant provided sustained CNS delivery of brain derived neurotrophic factor (BDNF) AntagoNATs for up to 4 weeks in Sprague Dawley rats resulting in significant endogenous BDNF protein upregulation in several brain tissues. The biocompatibility of such core-shell implants coupled with their substantial pharmacokinetic advantages and safety of the MIND procedure highlights the practical utility and translational potential of this synergistic approach for treatment of chronic age-related neurodegenerative diseases.

Brain derived neurotrophic factor mediates accelerated recovery of regenerative electrical stimulation in an animal model of stress urinary incontinence.

OBJECTIVE: Stress urinary incontinence (SUI) is prevalent among older women and can result from insufficient regeneration of the pudendal nerve (PN). Electrical stimulation (ES) of the PN upregulates brain derived neurotrophic factor (BDNF) and accelerates regeneration. Using tyrosine kinase B (TrkB) to reduce the availability of free BDNF, the aim of this study was to determine if BDNF is necessary for accelerated recovery via ES in a model of SUI. METHODS: Our SUI model consists of Female Sprague-Dawley rats, whose PNs were crushed bilaterally twice for 30 s, followed by insertion of a modified Foley catheter into the vagina with balloon inflation for 4 h. These rats were divided into 4 groups: 1) Sham PN crush and sham vaginal distension without electrode implantation and with saline treatment (sham injury); 2) SUI with sham stimulation and saline treatment (SUI); 3) SUI and ES with saline treatment (SUI&ES); and 4) SUI and ES with TrkB treatment (SUI&ES&TrkB). Animals underwent ES or sham stimulation four times a week for two weeks. Four weeks after injury, animals underwent functional testing consisting of leak point pressure (LPP) with simultaneous external urethral sphincter (EUS) electromyography (EMG) and pudendal nerve recordings. Data was analyzed using ANOVA with Holm-Sidak posthoc test (p < 0.05). EUS and PN specimen were sectioned and stained to semi-quantitatively evaluate morphology, regeneration, and reinnervation. RESULTS: LPP and EUS EMG firing rate were significantly increased in the sham injury and SUI&ES groups compared to the SUI and SUI&ES&TrkB groups. EUS of SUI rats showed few innervated neuromuscular junctions compared to sham injured rats, while both treatment groups showed an increase in reinnervated neuromuscular junctions. CONCLUSION: ES accelerates functional recovery via a BDNF-mediated pathway in a model of SUI. These findings suggest ES could be used as a potential regenerative therapy for women with SUI.

Xanthoceraside administration produces significant antidepressant effects in mice through activation of the hippocampal BDNF signaling pathway.

Current available antidepressants have various adverse reactions and slow pharmacodynamics, so it is necessary to find novel antidepressants for effective treatment. Xanthoceraside (XAN), a novel triterpenoid saponin extracted from the fruit husks of Xanthoceras sorbifolium Bunge, has anti-amnesic and neuroprotective properties. The purpose and significance of this study is to assess whether XAN has antidepressant effects in mice using the forced swim test (FST), tail suspension test (TST) and chronic unpredictable mild stress (CUMS) model of depression. The effects of XAN treatment on the hippocampal brain-derived neurotrophic factor (BDNF) signaling pathway and neurogenesis were examined. The antidepressant mechanism of XAN was explored using a BDNF inhibitor (K252a) and an anti-BDNF antibody. It was found that XAN administration significantly reversed the depressive-like behaviors of CUMS-treated mice. XAN treatment also significantly prevented the decreasing effects of CUMS on the hippocampal BDNF signaling and neurogenesis. The antidepressant effects of XAN in mice were blocked by both administration of K252a and anti-BDNF antibody. Collectively, these findings indicate that XAN possesses antidepressant effects in mice which are mediated by activation of hippocampal BDNF signaling pathway, thus providing the first evidence that XAN can be a potential antidepressant candidate.

Antidepressant Actions of Ketamine: Potential Role of L-Type Calcium Channels.

Recently, the United States Food and Drug Administration approved esketamine, the S-enantiomer of ketamine, as a fast-acting therapeutic drug for treatment-resistant depression. Although ketamine is known as an N-methyl-d-aspartate (NMDA) receptor antagonist, the underlying mechanisms of how it elicits an antidepressant effect, specifically at subanesthetic doses, are not clear and remain an advancing field of research interest. On the other hand, high-dose (more than the anesthetic dose) ketamine-induced neurotoxicity in animal models has been reported. There has been progress in understanding the potential pathways involved in ketamine-induced antidepressant effects, some of which include NMDA-receptor antagonism, modulation of voltage-gated calcium channels, and brain-derived neurotrophic factor (BDNF) signaling. Often these pathways have been shown to be linked. Voltage-gated L-type calcium channels have been shown to mediate the rapid-acting antidepressant effects of ketamine, especially involving induction of BDNF synthesis downstream, while BDNF deficiency decreases the expression of L-type calcium channels. This review focuses on the reported studies linking ketamine's rapid-acting antidepressant actions to L-type calcium channels with an objective to present a perspective on the importance of the modulation of intracellular calcium in mediating the effects of subanesthetic (antidepressant) versus high-dose ketamine (anesthetic and potential neurotoxicant), the latter having the ability to reduce intracellular calcium by blocking the calcium-permeable NMDA receptors, which is implicated in potential neurotoxicity.

Melamine disrupts spatial reversal learning and learning strategy via inhibiting hippocampal BDNF-mediated neural activity.

Although several studies showed adverse neurotoxic effects of melamine on hippocampus (HPC)-dependent learning and reversal learning, the evidence for this mechanism is still unknown. We recently demonstrated that intra-hippocampal melamine injection affected the induction of long-term depression, which is associated with novelty acquisition and memory consolidation. Here, we infused melamine into the HPC of rats, and employed behavioral tests, immunoblotting, immunocytochemistry and electrophysiological methods to sought evidence for its effects on cognitive flexibility. Rats with intra-hippocampal infusion of melamine displayed dose-dependent increase in trials to the criterion in reversal learning, with no locomotion or motivation defect. Compared with controls, melamine-treated rats avoided HPC-dependent place strategy. Meanwhile, the learning-induced BDNF level in the HPC neurons was significantly reduced. Importantly, bilateral intra-hippocampal BDNF infusion could effectively mitigate the suppressive effects of melamine on neural correlate with reversal performance, and rescue the strategy bias and reversal learning deficits. Our findings provide first evidence for the effect of melamine on cognitive flexibility and suggest that the reversal learning deficit is due to the inability to use place strategy. Furthermore, the suppressive effects of melamine on BDNF-mediated neural activity could be the mechanism, thus advancing the understanding of compulsive behavior in melamine-induced and other neuropsychiatric disorders.

The Secretome of Aged Fibroblasts Promotes EMT-Like Phenotype in Primary Keratinocytes from Elderly Donors through BDNF-TrkB Axis.

Age-related changes in the dermis can play a primary role in tumor initiation promoting the unrestrained proliferation of precancerous keratinocytes (KCs) through cytokines and GF secretion. We found a high percentage of epithelial-to-mesenchymal transition-like colonies raising in primary human KC cultures from old subjects after treatment with aged fibroblast supernatants (SPNs). Continuous extracellular signals were required for maintaining these changes. Conversely, the secretome did not induce epithelial-to-mesenchymal transition-like colonies in KCs from young subjects. SPN-treated aged KCs displayed the activation of pathways involved in the disjunction of cell‒cell adhesion, extracellular matrix remodeling, manifestation of a mesenchymal phenotype, and dedifferentiation programs. Moreover, they recovered proliferation and clonogenic ability and showed enhanced migration. We identified an age-related increase of the BDNF secretion from fibroblasts as well as of the expression of its receptor TrkB in KCs. BDNF treatment of aged KCs induced TrkB phosphorylation and recapitulated the modifications promoted by aged fibroblast SPN. Furthermore, the treatment with a specific antibody against BDNF or a TrkB antagonist inhibited the paracrine signaling preventing SPN-mediated morphological and molecular changes. Finally, BDNF induced signs of matrix invasion in a three-dimensional organotypic model. Therefore, we demonstrate that aged fibroblast SPN promotes phenotypic plasticity in KCs from the elderly through BDNF-TrkB axis.

Effects of Compound 511 on BDNF-TrkB Signaling in the Mice Ventral Tegmental Area in Morphine-Induced Conditioned Place Preference.

Compound 511 (511) is specially developed for opioid addiction treatment based on the Ancient Chinese drug rehabilitation literature, and its composition has profound effects in the treatment of drug addiction in various clinical trials and animal experiments. The effect of 511 on the rewarding properties of morphine and craving responses and its potential mechanisms remain unclear. Here, we have applied a conditioned place preference (CPP) paradigm in mice to measure morphine-induced rewarding effects under the treatment of 511. Then we used the RNA sequencing strategy to screen its potential mechanisms. In our research, firstly, we found 511 could decrease CPP score, locomotor activity, self-administration, jumping behavior, weight loss, wet-dog shakes, and stereotyped behavior. Then the brain VTA region tissues were performed mRNA sequencing to detect potential mechanisms. We found the brain-derived neurotrophic factor (BDNF) and tropomyosin-related kinase B (TrkB) were downregulated in morphine-induced CPP, whereas the decreased BDNF and TrkB were reversed after 511 treatment. We retested the levels of BDNF and TrkB using qRT-PCR and Western blot and found the similar results to mRNA sequencing. It has been widely reported that BDNF-TrkB signaling in the VTA is involved in multiple facets of addiction, including reward and motivation, so we focused on the BDNF-TrkB signaling to investigate the anti-addiction mechanisms of 511 in morphine addiction mice. We studied the downstream pathway of BDNF-TrkB and the soma size of dopaminergic neurons. The results showed 511 could increase the phosphorylation levels of PI3K and AKT, which were decreased in morphine-induced CPP. Simultaneously, 511 could decrease the level of PLCγ1 and the phosphorylation levels of ERK and S6K, which were increased in morphine-induced CPP. In addition, 511 also enlarged the soma size of VTA dopaminergic neurons, which was reduced in morphine-induced CPP. Hence, our research indicated 511 maybe mediate the BDNF-TrkB signaling in VTA to improve morphine addiction behavior.

Amitriptyline Protects Against Lidocaine-induced Neurotoxicity in SH-SY5Y Cells via Inhibition of BDNF-mediated Autophagy.

Amitriptyline (AMI) is a traditional tricyclic antidepressant that has been proven to exhibit neuroprotective effects in various neurological disorders. However, the underlying mechanism by which AMI attenuates lidocaine-induced neurotoxicity remains poorly understood. Brain-derived neurotrophic factor (BDNF) is an essential neurotrophin to neuronal development and survival in the brain, and recent studies have suggested that BDNF plays an important role in mediating lidocaine-induced neurotoxicity. The present study was performed to evaluate the protective effect of AMI against the neurotoxicity induced by lidocaine and to explore the role of BDNF-dependent autophagy in this process. The data showed that AMI pretreatment alleviated lidocaine-induced neurotoxicity, as evidenced by the restoration of cell viability, normalization of cell morphology, and reduction in the cell apoptosis index. In addition, autophagy inhibitor 3-methyladenine (3-MA) had a protective effect similar to that of AMI, but autophagy activator rapamycin eliminated the protective effect of AMI by suppressing mTOR activation. Moreover, at the molecular level, we found that AMI-mediated autophagy was involved in the expression of BDNF. The overexpression of BDNF or application of exogenous recombinant BDNF significantly suppressed autophagy and protected SH-SY5Y cells from apoptosis induced by Lido, whereas the neuroprotection of AMI was abolished by either knockdown of BDNF or use of a tropomyosin-related kinase B (TrkB) inhibitor ANA-12 in SH-SY5Y cells. Overall, our findings demonstrated that the protective effect of AMI against lidocaine-induced neurotoxicity correlated with inhibition of autophagy activity through upregulation of BDNF expression.

Brain-Derived Neurotrophic Factor Regulates Ishikawa Cell Proliferation through the TrkB-ERK1/2 Signaling Pathway.

(1) Background: Endometrial regulation is a necessary condition for maintaining normal uterine physiology, which is driven by many growth factors. Growth factors produced in the endometrium are thought to be related to the proliferation of endometrial cells induced by estradiol-17ß (E2). In this study, we found that E2 can induce the secretion of brain-derived neurotrophic factor (BDNF) in Ishikawa cells (the cells of an endometrial cell line). Furthermore, Ishikawa cells were used in exploring the regulatory role of BDNF in endometrial cells and to clarify the potential mechanism. (2) Methods: Ishikawa cells were treated with different concentrations of BDNF (100, 200, 300, 400, and 500 ng/mL). The mRNA expression levels of various proliferation-related genes were detected through quantitative reverse transcription polymerase chain reaction, and the expression of various proliferation-related genes was detected by knocking out BDNF or inhibiting the binding of BDNF to its receptor TrkB. The expression levels of various proliferation-related genes were detected by performing Western blotting on the TrkB-ERK1/2 signaling pathway. (3) Results: Exogenous BDNF promoted the growth of the Ishikawa cells, but the knocking down of BDNF or the inhibition of TrkB reduced their growth. Meanwhile, BDNF enhanced cell viability and increased the expression of proliferation-related genes, including cyclin D1 and cyclin E2. More importantly, the BDNF-induced proliferation of the Ishikawa cells involved the ERK1/2 signaling pathway. (4) Conclusions: The stimulating effect of exogenous E2 on the expression of BDNF in the uterus and the action of BDNF promoted the proliferation of the Ishikawa cells through the TrkB-ERK1/2 signal pathway.

The PI3K/Akt Cascade Is Involved in the Antidiabetic Effect of Compound GSB-214, a Low-Molecular-Weight BDNF Mimetic.

In our previous studies on the streptozotocin model of diabetes we hypothesized that activation of the PI3K/Akt signaling pathway is essential for the realization of the antidiabetic effect of low-molecular-weight NGF and BDNF mimetics. Here we analyze the effect of a specific PI3K/Akt pathway inhibitor (LY 294002) on the antidiabetic effect of the BDNF loop 1 mimetic GSB-214. The experiments on C57BL/6 mice with streptozotocin-induced diabetes showed that GSB-214 attenuated the hyperglycemic effect of streptozotocin and prevented weight loss typical of diabetes, while LY 294002 eliminated these effects of GSB-214. These findings clearly demonstrate the involvement of PI3K/Akt pathway in the implementation of the effects of this low-molecular-weight BDNF mimetic.

Reversal of pre-existing NGFR-driven tumor and immune therapy resistance.

Melanomas can switch to a dedifferentiated cell state upon exposure to cytotoxic T cells. However, it is unclear whether such tumor cells pre-exist in patients and whether they can be resensitized to immunotherapy. Here, we chronically expose (patient-derived) melanoma cell lines to differentiation antigen-specific cytotoxic T cells and observe strong enrichment of a pre-existing NGFRhi population. These fractions are refractory also to T cells recognizing non-differentiation antigens, as well as to BRAF + MEK inhibitors. NGFRhi cells induce the neurotrophic factor BDNF, which contributes to T cell resistance, as does NGFR. In melanoma patients, a tumor-intrinsic NGFR signature predicts anti-PD-1 therapy resistance, and NGFRhi tumor fractions are associated with immune exclusion. Lastly, pharmacologic NGFR inhibition restores tumor sensitivity to T cell attack in vitro and in melanoma xenografts. These findings demonstrate the existence of a stable and pre-existing NGFRhi multitherapy-refractory melanoma subpopulation, which ought to be eliminated to revert intrinsic resistance to immunotherapeutic intervention.

The pudendal nerve motor branch regenerates via a brain derived neurotrophic factor mediated mechanism.

Peripheral nerve injuries can significantly reduce quality of life. While some recover, most do not recover fully, resulting in neuropathic pain and loss of sensation and motor function. Research on the mechanisms of peripheral nerve regeneration could elucidate poor patient outcomes and potential treatments. This study was designed to determine if brain derived neurotrophic factor (BDNF) is necessary for pudendal nerve regeneration and functional recovery. Peripheral administration of tyrosine kinase B functional chimera (TrkB) was used to inhibit the BDNF regenerative pathway. Female Sprague-Dawley rats received tyrosine kinase B functional chimera (TrkB) or saline after a pudendal nerve crush (PNC) or Sham PNC and were divided into three groups: Sham PNC, PNC + Saline, and PNC + TrkB. Seven days after injury, relative ßII tubulin expression (1.0 ± 0.2) was significantly decreased after PNC + TrkB compared to PNC + saline (2.9 ± 1.0). Three weeks after injury, BDNF plasma concentration (1320.8 ± 278.1 pg/ml) was significantly reduced in PNC + TrkB compared to PNC + saline rats (2053.4 ± 211.0 pg/ml). Pudendal nerve motor branch firing rate (54.0 ± 9.5 Hz) was significantly decreased in the PNC + TrkB group compared to the PNC + saline group (120.4 ± 17.1 Hz); while nerve firing rate of the PNC + saline group was not significantly different from sham PNC rats (121.8 ± 26.6 Hz). This study demonstrated that peripheral administration of TrkB bound free BDNF and inhibited the regenerative response after PNC. BDNF is necessary for normal PN motor branch recovery after PNC.

A Tellurium-Based Small Immunomodulatory Molecule Ameliorates Depression-Like Behavior in Two Distinct Rat Models.

Major depressive disorder (MDD) is a leading cause of morbidity, and the fourth leading cause of disease burden worldwide. While MDD is a treatable condition for many individuals, others suffer from treatment-resistant depression (TRD). Here, we suggest the immunomodulatory compound AS101 as novel therapeutic alternative. We previously showed in animal models that AS101 reduces anxiety-like behavior and elevates levels of the brain-derived neurotrophic factor (BDNF), a protein that has a key role in the pathophysiology of depression. To explore the potential antidepressant properties of AS101, we used the extensively characterized chronic mild stress (CMS) model, and the depressive rat line (DRL Finally, in Exp. 3 to attain insight into the mechanism we knocked down BDNF in the hippocampus, and demonstrated that the beneficial effect of AS101 was abrogated. Together with the previously established safety profile of AS101 in humans, these results may represent the first step towards the development of a novel treatment option for MDD and TRD.

Ketamine and Ro 25-6981 Reverse Behavioral Abnormalities in Rats Subjected to Dietary Zinc Restriction.

Clinical and preclinical studies indicate that zinc (Zn) is an essential factor in the development and treatment of major depressive disorder (MDD). Conventional monoamine-based antidepressants mobilize zinc in the blood and brain of depressed patients as well as rodents. N-methyl-D-aspartate acid receptor (NMDAR) antagonists exhibit antidepressant-like activity. However, not much is known about the antidepressant efficacy of NMDAR antagonists in zinc-deficient (ZnD) animals. We evaluated the antidepressant-like activity of two NMDAR antagonists (ketamine; global NMDAR antagonist and Ro 25-6981 (Ro); selective antagonist of the GluN2B NMDAR subunit) in ZnD rats using the forced swim test (FST) and sucrose intake test (SIT). A single dose of either Ro 25-6981 or ketamine normalized depressive-like behaviors in ZnD rats; however, Ro was effective in both tests, while ketamine was only effective in the FST. Additionally, we investigated the mechanism of antidepressant action of Ro at the molecular (analysis of protein expression by Western blotting) and anatomical (density of dendritic spines by Golgi Cox-staining) levels. ZnD rats exhibited decreased phosphorylation of the p70S6K protein, and enhanced density of dendritic spines in the prefrontal cortex (PFC) compared to control rats. The antidepressant-like activity of Ro was associated with the increased phosphorylation of p70S6K and ERK in the PFC. In summary, single doses of the NMDAR antagonists ketamine and Ro exhibited antidepressant-like activity in the ZnD animal model of depression. Animals were only deprived of Zn for 4 weeks and the biochemical effects of Zn deprivation and Ro were investigated in the PFC and hippocampus. The shorter duration of dietary Zn restriction may be a limitation of the study. However, future studies with longer durations of dietary Zn restriction, as well as the investigation of multiple brain structures, are encouraged as a supplement to this study.

Neonatal DEX exposure leads to hyperanxious and depressive-like behaviors as well as a persistent reduction of BDNF expression in developmental stages.

Brain-derived neurotrophic factor (BDNF), which regulates the neuronal survival, differentiation and synaptic plasticity, has been proved to play a critical role in the pathology and treatment of several psychiatric disorders including depression. Dexamethaone (DEX) is indicated for a number of conditions in perinatal medicine, however, the long-term impact of early-life DEX exposure on BDNF expression in hippocampus remains unknown. Here we found that neonatal DEX(ND) exposure leads to insignificant change of BDNF expression levels in the adulthood, albeit increased hyperanxious and depressive-like behaviors. However, the bdnf mRNA and BDNF protein levels were significantly reduced in all the hippocampal subregions during the developmental stages, including the perinatal period and puberty. We conclude that early life DEX exposure leads to a persistent disturbance of BDNF signaling during the developmental stages, which might be associated with the life-long impairment of hippocampal function.

The early, long-term inhibition of brain-derived neurotrophic factor improves voiding, and storage dysfunctions in mice with spinal cord injury.

AIMS: We examined the time course of urodynamic changes and the effect of the short or long-term inhibition of brain-derived neurotrophic factor (BDNF) from the early phase after spinal cord injury (SCI) in mice. METHODS: The spinal cord of female C57BL/6N mice was completely transected. We examined filling cystometry and bladder BDNF levels at 10, 20, and 30 days after SCI, with an additional day-5 measurement of BDNF. In a separate group of mice, anti-BDNF antibody (Ab) (10 µg/kg/h) was subcutaneously administered using osmotic pumps from day 3 after SCI, and single-filling cystometry was performed at 10 and 30 days (7 and 27 days of treatment, respectively) after SCI. RESULTS: Compared to spinal intact mice, bladder mucosal BDNF was increased at each time point after SCI with the maximal level at day 5 after SCI. Voiding efficiency was lower at each time point after SCI than that of spinal intact mice. The number of non-voiding contractions (NVC) during bladder filling was gradually increased with time. In both 10- and 30-day SCI groups treated with anti-BDNF Ab, voiding efficiency was improved, and the duration of notch-like intravesical pressure reductions during voiding bladder contractions was prolonged. The number of NVC was significantly decreased only in 30-day SCI mice with 27-day anti-BDNF treatment. CONCLUSIONS: Overexpression of BDNF is associated with the deterioration of voiding efficiency after SCI. The early-started, long-term inhibition of BDNF improved voiding dysfunction and was also effective to reduce the later-phase development of detrusor overactivity after SCI.

Matrine alleviates neurobehavioral alterations via modulation of JNK-mediated caspase-3 and BDNF/VEGF signaling in a mouse model of burn injury.

RATIONALE: The c-Jun N-terminal kinase (JNK) pathway and neurotrophic factor dysregulation play a critical role in the pathogenesis of neurobehavioral disorders (anxiety and depression). Targeting the JNK pathway and BDNF/VEGF signaling may signify a new avenue for the treatment of neurobehavioral disorders. OBJECTIVES: The present study investigated the effect of matrine (Mat) against anxiety- and depressive-like emotional status in an acute mouse model of burn injury and explores its underlying mechanism. METHODS: In the mouse model of thermal injury, anxiety- and depression-related behaviors were evaluated using the elevated plus-maze test, the light-dark box test, the open-field test, the forced swimming test, and the tail suspension test. The JNK/caspase-3 and BDNF/VEGF proteins were determined by immunohistochemistry. Additionally, proinflammatory cytokine, antioxidant, nitric oxide, and corticosterone levels were also measured. RESULTS: The results showed that treatment with Mat significantly improves anxiety- and depressive-like behaviors. It remarkably reduced the levels of proinflammatory cytokines, malondialdehyde, and nitric oxide in the hippocampus and prefrontal cortex of a mouse brain. It considerably improved burn-induced alteration in the antioxidant status, corticosterone, and BDNF/VEGF. It also inhibited burn-induced apoptotic signaling by downregulating the expression of JNK/caspase-3. Similarly, it prevented DNA damage and histopathological changes in the dentate gyrus of the hippocampus. Furthermore, molecular docking results showed that Mat possess better binding affinity for JNK/caspase-3 and BDNF/VEGF proteins. CONCLUSIONS: These findings provide convincing evidence that Mat improves anxiety- and depressive-like emotional status through modulation of JNK-mediated inflammatory, oxidative stress, apoptotic, and BDNF/VEGF signaling in an acute mouse model of burn injury.

In vitro affinity optimization of an anti-BDNF monoclonal antibody translates to improved potency in targeting chronic pain states in vivo.

The role of brain-derived neurotrophic factor (BDNF) signaling in chronic pain has been well documented. Given the important central role of BDNF in long term plasticity and memory, we sought to engineer a high affinity, peripherally-restricted monoclonal antibody against BDNF to modulate pain. BDNF shares 100% sequence homology across human and rodents; thus, we selected chickens as an alternative immune host for initial antibody generation. Here, we describe the affinity optimization of complementarity-determining region-grafted, chicken-derived R3bH01, an anti-BDNF antibody specifically blocking the TrkB receptor interaction. Antibody optimization led to the identification of B30, which has a > 300-fold improvement in affinity based on BIAcore, an 800-fold improvement in potency in a cell-based pERK assay and demonstrates exquisite selectivity over related neurotrophins. Affinity improvements measured in vitro translated to in vivo pharmacological activity, with B30 demonstrating a 30-fold improvement in potency over parental R3bH01 in a peripheral nerve injury model. We further demonstrate that peripheral BDNF plays a role in maintaining the plasticity of sensory neurons following nerve damage, with B30 reversing neuron hyperexcitability associated with heat and mechanical stimuli in a dose-dependent fashion. In summary, our data demonstrate that effective sequestration of BDNF via a high affinity neutralizing antibody has potential utility in modulating the pathophysiological mechanisms that drive chronic pain states.