Electroacupuncture regulates Rab5a-mediating NGF transduction to improve learning and memory ability in the early stage of AD mice.

AIMS: Nerve growth factor (NGF) loss is a potential factor for the degeneration of basal forebrain cholinergic neurons (BFCNs) in Alzheimer's disease (AD), and Rab5a is a key regulatory molecule of NGF signaling transduction. Here, we investigated the changes of Rab5a in 5 × FAD mice and further explored the mechanism of Electroacupuncture (EA) treatment in improving cognition in the early stage of AD. METHODS: The total Rab5a and Rab5a-GTP in 5-month-old 5 × FAD mice and wild-type mice were detected using WB and IP technologies. 5 × FAD mice were treated with EA at the Bai hui (DU20) and Shen ting (DU24) acupoints for 4 weeks and CRE/LOXP technology was used to confirm the role of Rab5a in AD mediated by EA stimulation. The Novel Object Recognition and Morris water maze tests were used to evaluate the cognitive function of 5 × FAD mice. The Nissl, immunohistochemistry, and Thioflavin S staining were used to observe pathological morphological changes in the basal forebrain circuit. The Golgi staining was used to investigate the synaptic plasticity of the basal forebrain circuit and WB technology was used to detect the expression levels of cholinergic-related and NGF signal-related proteins. RESULTS: The total Rab5a was unaltered, but Rab5a-GTP increased and the rab5a-positive early endosomes appeared enlarged in the hippocampus of 5 × FAD mice. Notably, EA reduced Rab5a-GTP in the hippocampus in the early stage of 5 × FAD mice. EA could improve object recognition memory and spatial learning memory by reducing Rab5a activity in the early stage of 5 × FAD mice. Moreover, EA could reduce Rab5a activity to increase NGF transduction and increase the levels of phosphorylated TrkA, AKT, and ERK in the basal forebrain and hippocampus, and increase the expression of cholinergic-related proteins, such as ChAT, vAchT, ChT1, m1AchR, and m2AchR in the basal forebrain and ChAT, m1AchR, and m2AchR in the hippocampus, improving synaptic plasticity in the basal forebrain hippocampal circuit in the early stage of 5 × FAD mice. CONCLUSIONS: Rab5a hyperactivation is an early pathological manifestation of 5 × FAD mice. EA could suppress Rab5a-GTP to promote the transduction of NGF signaling, and enhance the synaptic plasticity of the basal forebrain hippocampal circuit improving cognitive impairment in the early stage of 5 × FAD mice.

Nerve Bundle Density and Expression of NGF and IL-1ß Are Intra-Individually Heterogenous in Subtypes of Endometriosis.

Endometriosis is a gynecological disorder associated with local inflammation and neuroproliferation. Increased nerve bundle density has been attributed to increased expression of nerve growth factor (NGF) and interleukin-1ß (IL-1ß). Immunohistochemical analysis was carried out on 12 patients presenting with all three anatomic subtypes of endometriosis (deep, superficial peritoneal, endometrioma) at surgery, with at least two surgically excised subtypes available for analysis. Immunolocalization for nerve bundle density around endometriosis using protein gene product 9.5 (PGP9.5), as well as NGF and IL-1ß histoscores in endometriosis epithelium/stroma, was performed to evaluate differences in scores between lesions and anatomic subtypes per patient. Intra-individual heterogeneity in scores across lesions was assessed using the coefficient of variation (CV). The degree of score variability between subtypes was evaluated using the percentage difference between mean scores from one subtype to another subtype for each marker. PGP9.5 nerve bundle density was heterogenous across multiple subtypes of endometriosis, ranging from 50.0% to 173.2%, where most patients (8/12) showed CV ≥ 100%. The percentage difference in scores showed that PGP9.5 nerve bundle density and NGF and IL-1ß expression were heterogenous between anatomic subtypes within the same patient. Based on these observations of intra-individual heterogeneity, we conclude that markers of neuroproliferation in endometriosis should be stratified by anatomic subtype in future studies of clinical correlation.

EFA6A, an Exchange Factor for Arf6, Regulates NGF-Dependent TrkA Recycling From Early Endosomes and Neurite Outgrowth in PC12 Cells.

Endosomal trafficking of TrkA is a critical process for nerve growth factor (NGF)-dependent neuronal cell survival and differentiation. The small GTPase ADP-ribosylation factor 6 (Arf6) is implicated in NGF-dependent processes in PC12 cells through endosomal trafficking and actin cytoskeleton reorganization. However, the regulatory mechanism for Arf6 in NGF signaling is largely unknown. In this study, we demonstrated that EFA6A, an Arf6-specific guanine nucleotide exchange factor, was abundantly expressed in PC12 cells and that knockdown of EFA6A significantly inhibited NGF-dependent Arf6 activation, TrkA recycling from early endosomes to the cell surface, prolonged ERK1/2 phosphorylation, and neurite outgrowth. We also demonstrated that EFA6A forms a protein complex with TrkA through its N-terminal region, thereby enhancing its catalytic activity for Arf6. Similarly, we demonstrated that EFA6A forms a protein complex with TrkA in cultured dorsal root ganglion (DRG) neurons. Furthermore, cultured DRG neurons from EFA6A knockout mice exhibited disturbed NGF-dependent TrkA trafficking compared with wild-type neurons. These findings provide the first evidence for EFA6A as a key regulator of NGF-dependent TrkA trafficking and signaling.

Targeting nerve growth factor-mediated osteosarcoma metastasis: mechanistic insights and therapeutic opportunities using larotrectinib.

Osteosarcoma (OS) therapy presents numerous challenges, due largely to a low survival rate following metastasis onset. Nerve growth factor (NGF) has been implicated in the metastasis and progression of various cancers; however, the mechanism by which NGF promotes metastasis in osteosarcoma has yet to be elucidated. This study investigated the influence of NGF on the migration and metastasis of osteosarcoma patients (88 cases) as well as the underlying molecular mechanisms, based on RNA-sequencing and gene expression data from a public database (TARGET-OS). In osteosarcoma patients, the expression of NGF was significantly higher than that of other growth factors. This observation was confirmed in bone tissue arrays from 91 osteosarcoma patients, in which the expression levels of NGF and matrix metallopeptidase-2 (MMP-2) protein were significantly higher than in normal bone, and strongly correlated with tumor stage. In summary, NGF is positively correlated with MMP-2 in human osteosarcoma tissue and NGF promotes osteosarcoma cell metastasis by upregulating MMP-2 expression. In cellular experiments using human osteosarcoma cells (143B and MG63), NGF upregulated MMP-2 expression and promoted wound healing, cell migration, and cell invasion. Pre-treatment with MEK and ERK inhibitors or siRNA attenuated the effects of NGF on cell migration and invasion. Stimulation with NGF was shown to promote phosphorylation along the MEK/ERK signaling pathway and decrease the expression of microRNA-92a-1-5p (miR-92a-1-5p). In in vivo experiments involving an orthotopic mouse model, the overexpression of NGF enhanced the effects of NGF on lung metastasis. Note that larotrectinib (a tropomyosin kinase receptor) strongly inhibited the effect of NGF on lung metastasis. In conclusion, it appears that NGF promotes MMP-2-dependent cell migration by inhibiting the effects of miR-92a-1-5p via the MEK/ERK signaling cascade. Larotrectinib emerged as a potential drug for the treatment of NGF-mediated metastasis in osteosarcoma.

Regulating tumor innervation by nanodrugs potentiates cancer immunochemotherapy and relieve chemotherapy-induced neuropathic pain.

Sympathetic nerves play a pivotal role in promoting tumor growth through crosstalk with tumor and stromal cells. Chemotherapy exacerbates the infiltration of sympathetic nerves into tumors, thereby providing a rationale for inhibiting sympathetic innervation to enhance chemotherapy. Here, we discovered that doxorubicin increases the density and activity of sympathetic nerves in breast cancer mainly by upregulating the expression of nerve growth factors (NGFs) in cancer cells. To address this, we developed a combination therapy by co-encapsulating small interfering RNA (siRNA) and doxorubicin within breast cancer-targeted poly (lactic-co-glycolic acid) (PLGA) nanoparticles, aiming to suppress NGF expression post-chemotherapy. Incorporating NGF blockade into the nanoplatform for chemotherapy effectively mitigated the chemotherapy-induced proliferation of sympathetic nerves. This not only bolstered the tumoricidal activity of chemotherapy, but also amplified its stimulatory impact on the antitumor immune response by increasing the infiltration of immunostimulatory cells into tumors while concurrently reducing the frequency of immunosuppressive cells. Consequently, the combined nanodrug approach, when coupled with anti-PD-L1 treatment, exhibited a remarkable suppression of primary and deeply metastatic tumors with minimal systematic toxicity. Importantly, the nanoplatform relieved chemotherapy-induced peripheral neuropathic pain (CIPNP) by diminishing the expression of pain mediator NGFs. In summary, this research underscores the significant potential of NGF knockdown in enhancing immunochemotherapy outcomes and presents a nanoplatform for the highly efficient and low-toxicity treatment of breast cancer.

Penehyclidine hydrochloride improves cognitive function of rats with brain injury via CAMP/CREB signaling pathway.

This study explored the impact of penehyclidine hydrochloride on cognitive function in rats with brain injury. Sprague-Dawley rats (n=36) were randomly assigned to sham-operation, model, and penehyclidine hydrochloride groups. Rats in the sham-operation group underwent craniotomy, while the model and penehyclidine hydrochloride groups received brain injury models and interventions with normal saline and penehyclidine hydrochloride, respectively. Specimens were obtained two weeks post-intervention. Neurological deficits were evaluated using Zea-Longa scores, and memory was assessed with the Morris water maze test. ELISA determined brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) content. mRNA expressions of BDNF and NGF were assessed via qPCR, and phosphorylated CREB (p-CREB) protein expression was measured by Western blotting. Compared to the sham-operation group, both model and penehyclidine hydrochloride groups showed increased Zea-Longa scores. Escape latencies were longer and platform crossings were fewer in model and penehyclidine hydrochloride groups compared to the sham-operation group, but penehyclidine hydrochloride demonstrated a shorter latency and more platform crossings than the model group. BDNF and NGF content decreased in model and penehyclidine hydrochloride groups compared to the sham-operation group, with an increase in the penehyclidine hydrochloride group compared to the model group. mRNA expression levels declined in model and penehyclidine hydrochloride groups but were higher in the latter. p-CREB protein expression was lower in model and penehyclidine hydrochloride groups compared to the sham-operation group but higher in the penehyclidine hydrochloride group than the model group. Penehyclidine hydrochloride exhibited neuroprotective effects by upregulating the cAMP/CREB signaling pathway, improving cognitive function in rats with brain injury.

The alterations in nerve growth factor concentration in plasma and synovial fluid before and after total knee arthroplasty.

Total knee arthroplasty (TKA) is an effective procedure for pain relief; however, the emergence of postsurgical pain remains a concern. In this study, we investigated the production of nerve growth factor (NGF) and mediators that affect NGF production and their function in the synovial fluid and plasma after TKA. This study included 19 patients (20 knees) who had rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and knee osteoarthritis (OA) who underwent TKA, categorized into OA and non-OA groups. The levels of NGF, inflammatory cytokines, and lipid mediators were analyzed before and after surgery. The intraoperative synovial fluid NGF concentration was more than seven times higher in the non-OA group than in the OA group. The intra-articular NGF levels increased significantly by more than threefold postoperatively in the OA group but not in the non-OA group. Moreover, the levels of inflammatory cytokines and lipid mediators were increased in the synovial fluid of both groups. The intra-articular cytokines or NGF concentrations positively correlated with postoperative pain. Targeted NGF control has the potential to alleviate postsurgical pain in TKA, especially in patients with OA, emphasizing the importance of understanding NGF dynamics under different knee conditions.

Amygdalar neurotransmission alterations in the BTBR mice model of idiopathic autism.

Autism Spectrum Disorders (ASD) are principally diagnosed by three core behavioural symptoms, such as stereotyped repertoire, communication impairments and social dysfunctions. This complex pathology has been linked to abnormalities of corticostriatal and limbic circuits. Despite experimental efforts in elucidating the molecular mechanisms behind these abnormalities, a clear etiopathogenic hypothesis is still lacking. To this aim, preclinical studies can be really helpful to longitudinally study behavioural alterations resembling human symptoms and to investigate the underlying neurobiological correlates. In this regard, the BTBR T+ Itpr3tf/J (BTBR) mice are an inbred mouse strain that exhibits a pattern of behaviours well resembling human ASD-like behavioural features. In this study, the BTBR mice model was used to investigate neurochemical and biomolecular alterations, regarding Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor (BDNF), together with GABAergic, glutamatergic, cholinergic, dopaminergic and noradrenergic neurotransmissions and their metabolites in four different brain areas, i.e. prefrontal cortex, hippocampus, amygdala and hypothalamus. In our results, BTBR strain reported decreased noradrenaline, acetylcholine and GABA levels in prefrontal cortex, while hippocampal measurements showed reduced NGF and BDNF expression levels, together with GABA levels. Concerning hypothalamus, no differences were retrieved. As regarding amygdala, we found reduced dopamine levels, accompanied by increased dopamine metabolites in BTBR mice, together with decreased acetylcholine, NGF and GABA levels and enhanced glutamate content. Taken together, our data showed that the BTBR ASD model, beyond its face validity, is a useful tool to untangle neurotransmission alterations that could be underpinned to the heterogeneous ASD-like behaviours, highlighting the crucial role played by amygdala.

Effect of flipped venous catheter combined with spinal cord electrical stimulation on functional recovery in patients with sciatic nerve injury.

OBJECTIVE: This study aimed to explore the effect of flipped venous catheters combined with spinal cord electrical stimulation on functional recovery in patients with sciatic nerve injury. PATIENTS AND METHODS: 160 patients with hip dislocation and sciatic nerve injury were divided into conventional release and flipped catheter + electrical stimulation groups according to the treatment methods (n=80). Motor nerve conduction velocity (MCV) and lower limb motor function were compared. Serum neurotrophic factors brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were compared. The frequency of complications and quality of life were also compared. RESULTS: The MCV levels of the common peroneal nerve and tibial nerve in the flipped catheter + electrical stimulation group were greater than the conventional lysis group (p<0.05). After treatment, the lower extremity motor score (LMEs) in the flipped catheter + electrical stimulation group was greater than the conventional lysis group (p<0.05). The serum levels of BDNF and NGF in the flip catheter + electrical stimulation group were higher than the conventional lysis group (p<0.05). The complication rate in the flipped catheter + electrical stimulation group was lower than in the conventional release group (6.25% vs. 16.25%, p<0.05). The quality-of-life score in the flip catheter + electrical stimulation group was greater than the conventional lysis group (p<0.05). CONCLUSIONS: The flipped venous catheter combined with spinal cord electrical stimulation can improve nerve conduction velocity, lower limb motor function, serum BDNF and NGF levels, reduce complications, and help improve the quality of life of sufferers with sciatic nerve injury. Chictr.org.cn ID: ChiCTR2400080984.

Nerve growth factor receptor limits inflammation to promote remodeling and repair of osteoarthritic joints.

Osteoarthritis (OA) is a painful, incurable disease affecting over 500 million people. Recent clinical trials of the nerve growth factor (NGF) inhibitors in OA patients have suggested adverse effects of NGF inhibition on joint structure. Here we report that nerve growth factor receptor (NGFR) is upregulated in skeletal cells during OA and plays an essential role in the remodeling and repair of osteoarthritic joints. Specifically, NGFR is expressed in osteochondral cells but not in skeletal progenitor cells and induced by TNFα to attenuate NF-κB activation, maintaining proper BMP-SMAD1 signaling and suppressing RANKL expression in mice. NGFR deficiency hyper-activates NF-κB in murine osteoarthritic joints, which impairs bone formation and enhances bone resorption as exemplified by a reduction in subchondral bone and osteophytes. In human OA cartilage, NGFR is also negatively associated with NF-κB activation. Together, this study suggests a role of NGFR in limiting inflammation for repair of diseased skeletal tissues.

[Neurotrophin-associated mechanisms of delayed-onset muscle soreness: research progress and perspective].

Delayed-onset muscle soreness (DOMS) is a common phenomenon that occurs following a sudden increase in exercise intensity or unfamiliar exercise, significantly affecting athletic performance and efficacy in athletes and fitness individuals. DOMS is characterized by allodynia and hyperalgesia, and their mechanisms remain unclear. Recent studies have reported that neurotrophic factors, such as nerve growth factor (NGF) and glial cell derived neurotrophic factor (GDNF), are involved in the development and maintenance of DOMS. This article provides a review of the research progress on the signaling pathways related to the involvement of NGF and GDNF in DOMS, hoping to provide novel insights into the mechanisms underlying allodynia and hyperalgesia in DOMS, as well as potential targeted treatment.

BDNF- and VEGF-Responsive Stimulus to an NGF Mimic Cyclic Peptide with Copper Ionophore Capability and Ctr1/CCS-Driven Signaling.

Neurotrophins are a family of growth factors that play a key role in the development and regulation of the functioning of the central nervous system. Their use as drugs is made difficult by their poor stability, cellular permeability, and side effects. Continuing our effort to use peptides that mimic the neurotrophic growth factor (NGF), the family model protein, and specifically the N-terminus of the protein, here we report on the spectroscopic characterization and resistance to hydrolysis of the 14-membered cyclic peptide reproducing the N-terminus sequence (SSSHPIFHRGEFSV (c-NGF(1-14)). Far-UV CD spectra and a computational study show that this peptide has a rigid conformation and left-handed chirality typical of polyproline II that favors its interaction with the D5 domain of the NGF receptor TrkA. c-NGF(1-14) is able to bind Cu2+ with good affinity; the resulting complexes have been characterized by potentiometric and spectroscopic measurements. Experiments on PC12 cells show that c-NGF(1-14) acts as an ionophore, influencing the degree and the localization of both the membrane transporter (Ctr1) and the copper intracellular transporter (CCS). c-NGF(1-14) induces PC12 differentiation, mimics the protein in TrkA phosphorylation, and activates the kinase cascade, inducing Erk1/2 phosphorylation. c-NGF(1-14) biological activities are enhanced when the peptide interacts with Cu2+ even with the submicromolar quantities present in the culture media as demonstrated by ICP-OES measurements. Finally, c-NGF(1-14) and Cu2+ concur to activate the cAMP response element-binding protein CREB that, in turn, induces the brain-derived neurotrophic factor (BDNF) and the vascular endothelial growth factor (VEGF) release.

NGF increases Connexin-43 expression and function in pulmonary arterial smooth muscle cells to induce pulmonary artery hyperreactivity.

AIMS: Pulmonary hypertension (PH) is characterised by an increase in pulmonary arterial pressure, ultimately leading to right ventricular failure and death. We have previously shown that nerve growth factor (NGF) plays a critical role in PH. Our objectives here were to determine whether NGF controls Connexin-43 (Cx43) expression and function in the pulmonary arterial smooth muscle, and whether this mechanism contributes to NGF-induced pulmonary artery hyperreactivity. METHODS AND RESULTS: NGF activates its TrkA receptor to increase Cx43 expression, phosphorylation, and localization at the plasma membrane in human pulmonary arterial smooth muscle cells, thus leading to enhanced activity of Cx43-dependent GAP junctions as shown by Lucifer Yellow dye assay transfer and fluorescence recovery after photobleaching -FRAP- experiments. Using both in vitro pharmacological and in vivo SiRNA approaches, we demonstrate that NGF-dependent increase in Cx43 expression and activity in the rat pulmonary circulation causes pulmonary artery hyperreactivity. We also show that, in a rat model of PH induced by chronic hypoxia, in vivo blockade of NGF or of its TrkA receptor significantly reduces Cx43 increased pulmonary arterial expression induced by chronic hypoxia and displays preventive effects on pulmonary arterial pressure increase and right heart hypertrophy. CONCLUSIONS: Modulation of Cx43 by NGF in pulmonary arterial smooth muscle cells contributes to NGF-induced alterations of pulmonary artery reactivity. Since NGF and its TrkA receptor play a role in vivo in Cx43 increased expression in PH induced by chronic hypoxia, these NGF/Cx43-dependent mechanisms may therefore play a significant role in human PH pathophysiology.

HDAC6-dependent deacetylation of NGF dictates its ubiquitination and maintains primordial follicle dormancy.

Rationale: Primordial follicles are limited in number and cannot be regenerated, dormant primordial follicles cannot be reversed once they enter a growth state. Therefore, the length of the female reproductive lifespan depends on the orderly progression and selective activation of primordial follicles, the mechanism of which remains unclear. Methods: We used human ovarian cortical biopsy specimens, granulosa cells from diminished ovarian reserve (DOR) patients, Hdac6-overexpressing transgenic mouse model, and RNA sequencing to analyze the crucial roles of histone deacetylase 6 (HDAC6) in fertility preservation and primordial follicle activation. Results: In the present study, we found that HDAC6 was highly expressed in most dormant primordial follicles. The HDAC6 expression was reduced accompanying reproductive senescence in human and mouse ovaries. Overexpression of Hdac6 delayed the rate of primordial follicle activation, thereby prolonging the mouse reproductive lifespan. Short-term inhibition of HDAC6 promoted primordial follicle activation and follicular development in humans and mice. Mechanism studies revealed that HDAC6 directly interacted with NGF, reducing acetylation modification of NGF and thereby accelerating its ubiquitination degradation. Consequently, the reduced NGF protein level maintained the dormancy of primordial follicles. Conclusions: The physiological significance of the high expression of HDAC6 in most primordial follicles is to reduce NGF expression and prevent primordial follicle activation to maintain female fertility. Reduced HDAC6 expression increases NGF expression in primordial follicles, activating their development and contributing to reproduction. Our study provides a clinical reference value for fertility preservation.

Targeting Molecular Mechanisms of Obesity- and Type 2 Diabetes Mellitus-Induced Skeletal Muscle Atrophy with Nerve Growth Factor.

Skeletal muscle plays a critical role in metabolic diseases, such as obesity and type 2 diabetes mellitus (T2DM). Muscle atrophy, characterized by a decrease in muscle mass and function, occurs due to an imbalance between the rates of muscle protein synthesis and degradation. This study aimed to investigate the molecular mechanisms that lead to muscle atrophy in obese and T2DM mouse models. Additionally, the effect of nerve growth factor (NGF) on the protein synthesis and degradation pathways was examined. Male mice were divided into three groups: a control group that was fed a standard chow diet, and two experimental groups that were fed a Western diet. After 8 weeks, the diabetic group was injected with streptozotocin to induce T2DM. Each group was then further divided into NGF-treated or non-treated control group. In the gastrocnemius muscles of the Western diet group, increased expressions of myostatin, autophagy markers, and ubiquitin ligases were observed. Skeletal muscle tissue morphology indicated signs of muscle atrophy in both obese and diabetic mice. The NGF-treated group showed a prominent decrease in the protein levels of myostatin and autophagy markers. Furthermore, the NGF-treated group showed an increased Cyclin D1 level. Western diet-induced obesity and T2DM may be linked to muscle atrophy through upregulation of myostatin and subsequent increase in the ubiquitin and autophagy systems. Moreover, NGF treatment may improve muscle protein synthesis and cell cycling.

Vascular smooth muscle cell-derived nerve growth factor regulates sympathetic collateral branching to innervate blood vessels in embryonic skin.

Blood vessels serve as intermediate conduits for the extension of sympathetic axons towards target tissues, while also acting as crucial targets for their homeostatic processes encompassing the regulation of temperature, blood pressure, and oxygen availability. How sympathetic axons innervate not only blood vessels but also a wide array of target tissues is not clear. Here we show that in embryonic skin, after the establishment of co-branching between sensory nerves and blood vessels, sympathetic axons invade the skin alongside these sensory nerves and extend their branches towards these blood vessels covered by vascular smooth muscle cells (VSMCs). Our mosaic labeling technique for sympathetic axons shows that collateral branching predominantly mediates the innervation of VSMC-covered blood vessels by sympathetic axons. The expression of nerve growth factor (NGF), previously known to induce collateral axon branching in culture, can be detected in the vascular smooth muscle cell (VSMC)-covered blood vessels, as well as sensory nerves. Indeed, VSMC-specific Ngf knockout leads to a significant decrease of collateral branching of sympathetic axons innervating VSMC-covered blood vessels. These data suggest that VSMC-derived NGF serves as an inductive signal for collateral branching of sympathetic axons innervating blood vessels in the embryonic skin.

Enhancing nerve regeneration in infraorbital nerve injury rat model: effects of vitamin B complex and photobiomodulation.

Orofacial nerve injuries may result in temporary or long-term loss of sensory function and decreased quality of life in patients. B vitamins are required for DNA synthesis and the repair and maintenance of phospholipids. In particular, vitamins B1, B6, and B12 are essential for neuronal function. Deficiency in vitamin B complex (VBC) has been linked to increased oxidative stress, inflammation and demyelination. Photobiomodulation (PBM) has antioxidant activity and is neuroprotective. In addition, a growing literature attests to the positive effects of PBM on nerve repair. To assess the effect of PBM and VBC on regenerative process we evaluated the expression of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), myelin basic protein (MBP), laminin and neurofilaments (NFs) using Western blotting to identify regenerative pattern after chronic constriction injury of the infraorbital nerve (CCI IoN) treated by PBM, VBC or its combination. After CCI IoN, the rats were divided into six groups naive, sham, injured (CCI IoN), treated with photobiomodulation (904 nm, 6.23 J/cm2, CCI IoN + PBM), treated with VBC (containing B1, B6 and B12) 5 times, CCI IoN + VBC) and treated with PBM and VBC (CCI IoN + VBC + PBM). The treatments could revert low expression of BDNF, MBP and laminin. Also reverted the higher expression of neurofilaments and enhanced expression of NGF. PBM and VBC could accelerate injured infraorbital nerve repair in rats through reducing the expression of neurofilaments, increasing the expression of BDNF, laminin and MBP and overexpressing NGF. These data support the notion that the use of PBM and VBC may help in the treatment of nerve injuries. This finding has potential clinical applications.

Metformin inhibits nerve growth factor-induced sympathetic neuron differentiation through p35/CDK5 inhibition.

The authors' previous research has shown the pivotal roles of cyclin-dependent kinase 5 (CDK5) and its regulatory protein p35 in nerve growth factor (NGF)-induced differentiation of sympathetic neurons in PC12 cells. During the process of differentiation, neurons are susceptible to environmental influences, including the effects of drugs. Metformin is commonly used in the treatment of diabetes and its associated symptoms, particularly in diabetic neuropathy, which is characterized by dysregulation of the sympathetic neurons. However, the impacts of metformin on sympathetic neuronal differentiation remain unknown. In this study, we investigated the impact of metformin on NGF-induced sympathetic neuronal differentiation using rat pheochromocytoma PC12 cells as a model. We examined the regulation of TrkA-p35/CDK5 signaling in NGF-induced PC12 differentiation. Our results demonstrate that metformin reduces NGF-induced PC12 differentiation by inactivating the TrkA receptor, subsequently inhibiting ERK and EGR1. Inhibition of this cascade ultimately leads to the downregulation of p35/CDK5 in PC12 cells. Furthermore, metformin inhibits the activation of the presynaptic protein Synapsin-I, a substrate of CDK5, in PC12 differentiation. In addition, metformin alters axonal and synaptic bouton formation by inhibiting p35 at both the axons and axon terminals in fully differentiated PC12 cells. In summary, our study elucidates that metformin inhibits sympathetic neuronal differentiation in PC12 cells by disrupting TrkA/ERK/EGR1 and p35/CDK5 signaling. This research contributes to uncovering a novel signaling mechanism in drug response during sympathetic neuronal differentiation, enhancing our understanding of the intricate molecular processes governing this critical aspect of neurodevelopment.NEW & NOTEWORTHY This study unveils a novel mechanism influenced by metformin during sympathetic neuronal differentiation. By elucidating its inhibitory effects from the nerve growth factor (NGF) receptor, TrkA, to the p35/CDK5 signaling pathways, we advance our understanding of metformin's mechanisms of action and emphasize its potential significance in the context of drug responses during sympathetic neuronal differentiation.

Mussel shell-derived pro-regenerative scaffold with conductive porous multi-scale-patterned microenvironment for spinal cord injury repair.

It is well-established that multi-scale porous scaffolds can guide axonal growth and facilitate functional restoration after spinal cord injury (SCI). In this study, we developed a novel mussel shell-inspired conductive scaffold for SCI repair with ease of production, multi-scale porous structure, high flexibility, and excellent biocompatibility. By utilizing the reducing properties of polydopamine, non-conductive graphene oxide (GO) was converted into conductive reduced graphene oxide (rGO) and crosslinkedin situwithin the mussel shells.In vitroexperiments confirmed that this multi-scale porous Shell@PDA-GO could serve as structural cues for enhancing cell adhesion, differentiation, and maturation, as well as promoting the electrophysiological development of hippocampal neurons. After transplantation at the injury sites, the Shell@PDA-GO provided a pro-regenerative microenvironment, promoting endogenous neurogenesis, triggering neovascularization, and relieving glial fibrosis formation. Interestingly, the Shell@PDA-GO could induce the release of endogenous growth factors (NGF and NT-3), resulting in the complete regeneration of nerve fibers at 12 weeks. This work provides a feasible strategy for the exploration of conductive multi-scale patterned scaffold to repair SCI.

Combined effect of Neurotropin® and methylcobalamin on postherpetic neuralgia in mice infected with herpes simplex virus type-1.

BACKGROUND: Postherpetic pain (PHP) is difficult to control. Although Neurotropin® (NTP) and methylcobalamin (MCB) are often prescribed to treat the pain, the efficacy of combined treatment for PHP remains imcompletely understood. OBJECTIVE: In this study, we investigate the combined effects of NTP and MCB on PHP in mice. METHODS: NTP and MCB were administered from day 10-29 after herpes simplex virus type-1 (HSV-1) infection. The pain-related responses were evaluated using a paint brush. The expression of neuropathy-related factor (ATF3) and nerve repair factors (GAP-43 and SPRR1A) in the dorsal root ganglion (DRG) and neurons in the skin were evaluated by immunohistochemical staining. Nerve growth factor (NGF) and neurotrophin-3 (NT3) mRNA expression levels were evaluated using real-time PCR. RESULTS: Repeated treatment with NTP and MCB after the acute phase inhibited PHP. Combined treatment with these drugs inhibited PHP at an earlier stage than either treatment alone. In the DRG of HSV-1-infected mice, MCB, but not NTP, decreased the number of cells expressing ATF3 and increased the number of cells expressing GAP-43- and SPRR1A. In addition, MCB, but not NTP, also increased and recovered non-myelinated neurons decreased in the lesional skin. NTP increased the mRNA levels of NTF3 in keratinocytes, while MCB increased that of NGF in Schwann cells. CONCLUSION: These results suggest that combined treatment with NTP and MCB is useful for the treatment of PHP. The combined effect may be attributed to the different analgesic mechanisms of these drugs.