Glial Cell Line-derived Neurotrophic Factor Research Articles

Accelerated innervation of biofabricated skeletal muscle implants containing a neurotrophic factor delivery system

IntroductionVolumetric muscle loss (VML) is one of the most severe and debilitating conditions in orthopedic and regenerative medicine. Current treatment modalities often fail to restore the normal structure and function of the damaged skeletal muscle. Bioengineered tissue constructs using the patient’s own cells have emerged as a promising alternative treatment option, showing positive outcomes in fostering new muscle tissue formation. However, achieving timely and proper innervation of the implanted muscle constructs remains a significant challenge. In this study, we present a clinically relevant strategy aimed at enhancing and sustaining the natural regenerative response of peripheral nerves to accelerate the innervation of biofabricated skeletal muscle implants.MethodsWe previously developed a controlled-release neurotrophic factor delivery system using poly (lactic-co-glycolic acid) (PLGA) microspheres encapsulating ciliary neurotrophic factor (CNTF) and glial cell line-derived neurotrophic factor (GDNF). Here, we incorporate this neurotrophic factor delivery system into bioprinted muscle constructs to facilitate innervation in vivo.ResultsOur results demonstrate that the neurotrophic factors released from the microspheres provide a chemical cue, significantly enhancing the neurite sprouting and functional innervation of the muscle cells in the biofabricated muscle construct within 12 weeks post-implantation.DiscussionOur approach provides a clinically applicable treatment option for VML through accelerated innervation of biomanufactured muscle implants and subsequent improvements in functionality.

Enhancement of enteric neural stem cell neurogenesis by glial cell-derived neurotrophic factor in experimental Hirschsprung's disease.

Stem cell therapy offers a promising solution for congenital diseases like Hirschsprung's disease (HSCR). Optimizing stem cell efficacy by modifying the cells and their environment is crucial, but in vitro culture conditions need to be further improved. Glial cell-derived neurotrophic factor (GDNF) plays an important role in neuronal survival, proliferation, migration and differentiation during enteric nervous system (ENS) development. In this study, the effects of GDNF on neurites derived from an Ednrb knockout model were investigated with the aim of enhancing the neurogenic potential of enteric neural crest cells (ENCCs). Neurospheres were generated form Ednrb+/+ (control) and Ednrb-/- mice at embryonic day13.5 (E13.5) with Sox10-green fluorescent protein (Venus) transgenic expression. These neurospheres were cultured in control media and neurospheres from Ednrb-/- were cultured with either control media or media supplemented with GDNF. ENCCs differentiation was assessed using immunofluorescence staining after 18days. GDNF-treated Ednrb-/- neurospheres showed increased size and higher density of Sox10-positive ENCCs compared to untreated Ednrb-/- neurospheres. GDNF also enhanced the distribution of both TUJ1-positive neurons and S100-positive glial cells. GDNF effectively enhanced the neurogenic potential of ENCCs from HSCR animal model. This finding is crucial for the development of cell therapy in HSCR.

Bidirectional two-sample Mendelian randomization analysis unveils causal association between inflammatory cytokines and the risk of diabetic nephropathy

ObjectivePrevious observational studies have indicated associations between various inflammatory cytokines and diabetic nephropathy (DN) caused by type 2 diabetes mellitus (T2DM). However, the causality remains unclear. We aimed to further evaluate the causal association between 91 inflammatory cytokines and DN using bidirectional two-sample Mendelian randomization (MR) analysis.MethodSummary statistics for DN were obtained from a publicly available genome-wide association study (GWAS) analysis. Data pertaining to inflammatory cytokines were derived from a GWAS protein quantitative trait locus (pQTL) study. The primary analytical approach employed the inverse variance weighted (IVW) method, complemented by MR-Egger regression, weighted mode (WM), and weighted median (WME) methods to evaluate the causal association between inflammatory cytokines and DN. Sensitivity analyses were conducted to validate the robustness of the findings.ResultAmong individuals of European ancestry, the IVW method results revealed a positive causal association between the gene expression of tumor necrosis factor ligand superfamily member 14 (TNFSF14), and TNF-related activation-induced cytokine (TRANCE) with DN. Conversely, a negative causal association was observed between the gene expression of interleukin-1-alpha (IL-1α), and transforming growth factor-alpha (TGF-α) with DN. Among individuals of East Asian ancestry, the IVW method results indicated a negative causal association between the gene expression of glial cell line-derived neurotrophic factor (GDNF) and DN. Notably, these findings persisted without evidence of horizontal pleiotropy or heterogeneity, ensuring their robustness and reliability.ConclusionThe MR analysis underscores a causal association between inflammatory cytokines and DN, providing an important reference and evidence for the study of DN.

Unveiling the Therapeutic Potential of Small Molecule of SVAK-12: A Comprehensive In Silico, In Vitro, and In Vivo Studies on its Neuroprotective Effects and Molecular Interactions in Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder associated with a progressive loss of dopaminergic cells and as of now, there is no established definitive treatment available for this condition. In this study, the focus was on investigating the impact of SVAK-12, a small molecule that can cross the blood-brain barrier and remain stable without structural changes. The effect of SVAK-12 was investigated in vitro on neurotoxicity, in vivo model of Parkinson's Diseases and in silico. Through in vitro and in vivo experiments, as well as molecular docking simulations, it was found that SVAK-12 (375 ng.ml) led to increased cell viability, reduced cellular damage, and decreased production of NO and ROS. Additionally, it boosted levels of important neurotrophic factors like BDNF (130.49%) and GDNF (116.38%), potentially aiding in alleviating motor disability and depression. The study also highlighted SVAK-12's potential as a therapeutic candidate for neurological disorders due to its ability to increase tyrosine hydroxylase expression and dopamine levels (4.84 times). While it did not significantly improve motor symptoms in vivo, it did enhance motor asymmetry in the forelimbs and gene expression related to brain regions. Besides, it induced significant BMP-2 gene expression in substantial nigra regions without significant changes in GDNF and Nurr1 gene expression in the striatum expression. The docking of SVAK-12, Levodopa, Amantadine, Biperiden, Selegiline, and Rasagiline to the binding site of GFRα1, sortilin, and TrkB showed that SVAK-12 had greater MolDock score than Selegiline and Amantadine for GFRα1 and greater than amantadine for Sortilin and TrKB. Overall, the study suggests that SVAK-12's neuro-biocompatibility, ability to reduce free radicals, and enhanced neurotrophic factors make it a promising candidate as a neuroprotective drug.

Exploring the Gene Expression and Plasma Protein Levels of HSP90, HSP60, and GDNF in Multiple Sclerosis Patients and Healthy Controls.

Multiple sclerosis (MS) is a chronic neurodegenerative disease characterized by immune-mediated inflammation and neurodegeneration in the central nervous system (CNS). In this study; we aimed to investigate the gene expression and plasma protein levels of three neuroprotective genes-heat shock proteins (HSP90 and HSP60) and glial cell line-derived neurotrophic factor (GDNF)-in MS patients compared to healthy controls. Forty patients with relapsing-remitting MS and 40 healthy volunteers participated in this study. Gene expression was measured using reverse transcription quantitative real-time PCR, and protein levels were assessed via ELISA. The results showed a significant increase in HSP90 (1.7-fold) and HSP60 (2-fold) gene expression in MS patients compared to controls, along with corresponding increases in protein levels (1.5-fold for both HSP90 and HSP60). In contrast, GDNF gene expression and protein levels were significantly reduced in MS patients, with a 7-fold decrease in gene expression and a 1.6-fold reduction in protein levels. Notably, a non-linear relationship between GDNF gene expression and protein concentration was observed in MS patients, suggesting complex regulatory mechanisms influencing GDNF in the disease. The upregulation of HSP90 and HSP60 in MS highlights their roles in immune regulation and stress responses, while the reduction in GDNF indicates impaired neuroprotection. These findings suggest that HSP90, HSP60, and GDNF could serve as biomarkers for disease progression and as potential therapeutic targets in MS, offering promising avenues for future research and treatment development.

Androgen blockage impairs proliferation and function of Sertoli cells via Wee1 and Lfng

BackgroundAndrogens are essential hormones for testicular development and the maintenance of male fertility. Environmental factors, stress, aging, and psychological conditions can disrupt androgen production, impacting the androgen signaling pathway and consequently spermatogenesis. Within the testes, testosterone is produced by Leydig cells and acts on Sertoli cells by activating the androgen receptor (AR), which then translocates to the nucleus to function as a transcription factor. Despite clinical correlations between low testosterone levels and diminished sperm quality, the precise mechanism remains unclear.MethodsThis study explores the hypothesis that reduced androgen levels impair Sertoli cell function by disrupting AR transcriptional regulation. Using an androgen blockade model with enzalutamide, we investigated the impact of low androgen levels on AR target genes in Sertoli cells through ChIP-seq and RNA-seq assays.ResultsOur results reveal that androgen blockage increases AR enrichment on the promoter region of Wee1, promoting Wee1 expression, while decreasing binding to the promoter region of Lfng, inhibiting its expression. Increased WEE1 protein inhibits Sertoli cell proliferation, whereas reduced LFNG affects Notch modification, leading to decreased production of glial cell line-derived neurotrophic factor (GDNF), a key growth factor for spermatogonial stem cell self-renewal.ConclusionsThese findings provide new insights into the molecular mechanisms by which low androgen levels interfere with Sertoli cell functions, offering novel perspectives for the clinical treatment of male reproductive disorders.

Blood Growth Factor Levels in Patients with Systemic Lupus Erythematosus: High Neuregulin-1 Is Associated with Comorbid Cardiovascular Pathology.

Patients with systemic lupus erythematosus (SLE) are known to frequently suffer from comorbid cardiovascular diseases (CVDs). There are abundant data on cytokine levels and their role in the pathogenesis of SLE, while growth factors have received much less attention. The aim of this study was to analyze growth factor levels in SLE patients and their association with the presence of comorbid CVDs. The serum concentrations for the granulocyte-macrophage colony-stimulating factor (GM-CSF), nerve growth factor β (NGFβ), glial cell line-derived neurotrophic factor (GDNF), and neuregulin-1 β (NRG-1β) were determined in the SLE patients (n = 35) and healthy individuals (n = 38) by a Luminex multiplex assay. The NGFβ and NRG-1β concentrations were shown to be significantly higher in the total group of SLE patients (median [Q1-Q3]: 3.6 [1.3-4.5] and 52.5 [8.5-148], respectively) compared with the healthy individuals (2.9 [1.3-3.4] and 13.7 [4.4-42] ng/mL, respectively). The GM-CSF and GDNF levels did not differ. Interestingly, elevated NRG-1β levels were associated with the presence of CVDs, as SLE patients with CVDs had significantly higher NRG-1β levels (99 [22-242]) compared with the controls (13.7 [4.4-42]) and patients without CVDs (19 [9-80] ng/mL). The model for the binary classification of SLE patients with and without CVDs based on the NRG-1β level had an average predictive ability (AUC = 0.67). Thus, altered levels of growth factors may be associated with comorbid CVDs in SLE patients.

Mechanisms of Electroacupuncture in Alleviating Visceral Hypersensitivity in Post-Infectious Irritable Bowel Syndrome Mice: The Role of GDNF Signaling Pathway and Gut Microbiota.

Post-infectious irritable bowel syndrome (PI-IBS) is a functional bowel disease that develops following an acute gastrointestinal infection. Electroacupuncture (EA) can regulate the gut microbiota and alleviate visceral hypersensitivity. Glial cell-derived neurotrophic factor (GDNF) is a potential factor in visceral hypersensitivity reactions. The aim of this study was to explore whether EA could alleviate visceral hypersensitivity in PI-IBS by regulating gut microbiota through GDNF signaling. 2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to induce visceral hypersensitivity in PI-IBS mice. Assessment of intestinal visceral sensitivity using the abdominal withdrawal reflex (CRD). 16S ribosomal RNA (16S rRNA) sequencing to profile the gut microbiome community. GDNF can exacerbate the imbalances of the gut microbiota and increase visceral hypersensitivity compared with the model group. Whereas EA treatment increases the richness and diversity of the gut microbiota, decreases differences among species and alleviates visceral sensitivity. EA can alleviate visceral hypersensitivity in PI-IBS by regulating the gut microbiota via GDNF signaling, providing new insights for mechanistic research on EA in PI-IBS treatment.

Advances in glial cell line-derived neurotrophic factor

Glial cell line-derived neurotrophic factor (GDNF) is a potent neurotrophic factor with significant research value due to its profound effects on dopaminergic, cholinergic, and motor neurons. Initially identified for its neuroprotective role in dopaminergic neurons, GDNF has been found to support various neuronal populations and plays a crucial role in neural development, maintenance, and repair. This review provides a comprehensive overview of the molecular characteristics, tissue distribution, physiological function of GDNF and its protective effect on a series of diseases, emphasizing its potential therapeutic applications. Meanwhile, this study discusses the challenges in delivering GDNF across the blood-brain barrier and explores current strategies to enhance its clinical efficacy, including the use of gene therapy and innovative delivery methods. In summary, the review underscores the promise of GDNF as a therapeutic agent for neurodegenerative diseases and nerve injuries, highlighting the need for further research to translate these findings into clinical practice.

Multi-loaded PLGA microspheres as neuroretinal therapy in a chronic glaucoma animal model.

This work focused on the co-encapsulation and simultaneous co-delivery of three different neuroprotective drugs in PLGA (poly(lactic-co-glycolic acid) microspheres for the treatment of glaucoma. For formulation optimization, dexamethasone (anti-inflammatory) and ursodeoxycholic acid (anti-apoptotic) were co-loaded by the solid-in-oil-in-water emulsion solvent extraction-evaporation technique as a first step. The incorporation of a water-soluble co-solvent (ethanol) and different amounts of dexamethasone resulted critical for the encapsulation of the neuroprotective agents and their initial release. The optimized formulation was obtained with 60mg of dexamethasone and using an 80:20 dichloromethane:ethanol ratio. In the second step in the microencapsulation process, the incorporation of the glial cell line-derived neurotrophic factor (GDNF) was performed. The final prototype showed encapsulation efficiencies for each component above 50% with suitable properties for long-term application for at least 3months. Physicochemical studies were performed by SEM, TEM, DSC, XRD, and gas chromatography. The evaluation of the kinetic release by the Gallagher-Corrigan analysis with Gorrasi correction helped to understand the influence of the co-microencapsulation on the delivery of the different actives from the optimized formulation. The final prototype was tested in a chronic glaucoma animal model. Rats received two intravitreal injections of the neuroprotective treatment within a 24-week follow-up study. The proposed formulation improved retinal ganglion cell (RGC) functionality examined by electroretinography. Also, it was able to maintain a neuroretinal thickness similar to that of healthy animals scanned by in vivo optical coherence tomography, and a higher RGC count on histology compared to glaucomatous animals at the end of the study.

Mechanisms of RET mediated signal transduction.

The RET receptor tyrosine kinase is physiologically stimulated by growth factors belonging to the glial cell line-derived neurotrophic factor (GDNF) family (GFLs) and by the growth differentiation factor-15 (GDF15) cytokine. RET plays a critical role in normal development as well as in various human tumors and developmental disorders. This review focuses on mechanisms of RET signaling and their alterations in human diseases.

Expression of Neurotrophic Factors and Their Receptors in the Rat Spinal Trigeminal Nucleus

The spinal trigeminal nucleus as part of the trigeminal sensory nuclear complex is associated with the transmission of discriminative tactile sensations, primarily pain, and temperature, from the orofacial region. It is divided into three parts – caudal, interpolar, and oral subnucleus which process pain and temperature stimulate. Our previous experiments have revealed the presence of certain neurotrophic factors such as the nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) in this nucleus. These neurotrophins facilitate neuronal differentiation, survival, and plasticity by signalling through high-affinity transmembrane receptors. By using primary antibodies against NGF, BDNF, NT-3, and glial-derived neurotrophic factor (GDNF), and their corresponding receptors of the tyrosine receptor kinase (Trk) proto-oncogene family and GFRα1, we found immunoreactive cells scattered along the whole length of the nucleus in rats in all three subnuclei. In particular, we observed that the majority of spinal trigeminal neurons were intensely immunostained for all the neurotrophic factors examined and that they were richly endowed with their Trk receptors. Our results also showed that NGF, NT-3, TrkC and GFRα1 expression did not differ between different topographic regions of the nucleus, while BDNF, GDNF, and TrkA expression was highest in the SpVo, and TrkB expression was highest in the SpVi and SpVc. Given that these neurotrophic factors are involved in mechanisms of central sensitization in trigeminal nociceptive pathways, it can be inferred that neurotrophins may contribute to a better understanding of the fundamental mechanisms of orofacial pain.

Glial-Cell-Line-Derived Neurotrophic Factor Promotes Glioblastoma Cell Migration and Invasion via the SMAD2/3-SERPINE1-Signaling Axis.

Glial-cell-line-derived neurotrophic factor (GDNF) is highly expressed and is involved in the malignant phenotype in glioblastomas (GBMs). However, uncovering its underlying mechanism for promoting GBM progression is still a challenging work. In this study, we found that serine protease inhibitor family E member 1 (SERPINE1) was a potential downstream gene of GDNF. Further experiments confirmed that SERPINE1 was highly expressed in GBM tissues and cells, and its levels of expression and secretion were enhanced by exogenous GDNF. SERPINE1 knockdown inhibited the migration and invasion of GBM cells promoted by GDNF. Mechanistically, GDNF increased SERPINE1 by promoting the phosphorylation of SMAD2/3. In vivo experiments demonstrated that GDNF facilitated GBM growth and the expressions of proteins related to migration and invasion via SERPINE1. Collectively, our findings revealed that GDNF upregulated SERPINE1 via the SMAD2/3-signaling pathway, thereby accelerating GBM cell migration and invasion. The present work presents a new mechanism of GDNF, supporting GBM development.

Comparative study about the therapeutic effect of cTBS and rTMS in the treatment of auditory verbal hallucinations in schizophrenia.

This study aims to compare the therapeutic effects of repetitive transcranial magnetic stimulation (rTMS) and continuous theta-burst stimulation (cTBS) treatment in schizophrenia patients with auditory verbal hallucinations (AVHs). We enrolled 64 schizophrenia patients with AVHs who were treated with either rTMS (n = 32) or cTBS (n = 32), and we compared the clinical outcomes by evaluating parameters from motor evoked potentials, Positive and Negative Syndrome Scale (PANSS), Auditory Hallucination Rating Scale (AHRS), and MATRICS Consensus Cognitive Battery (MCCB), as well as the changes of serum neurotrophic factors before and after the treatment. After the treatment, both treatments resulted in reduced PANSS scores, with the cTBS group showing more substantial symptom improvement across positive, negative, and general symptoms, highlighting the enhanced efficacy of cTBS. Cognitive functions assessed by MCCB also improved in both groups, with cTBS showing a generally higher therapeutic effect. Serum levels of brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) increased following treatment in both groups, with a more notable increase after cTBS, while GABA and glutamate levels remained unchanged. Cardiovascular indices were unaffected by either treatment, suggesting no significant impact on cardiovascular health. Our study found that both rTMS and cTBS treatment can exhibit therapeutic effects in the management of AVHs in patients with schizophrenia. However, cTBS treatment generally shows a higher therapeutic effect than rTMS treatment.

MIND Diet Impact on Multiple Sclerosis Patients: Biochemical Changes after Nutritional Intervention.

There is substantial evidence supporting the neuroprotective effects of the MIND diet in neurodegenerative diseases like Parkinson's and Alzheimer's. Our aim was to evaluate the impact of a nutritional intervention (NI) with this diet on multiple sclerosis (MS) patients. The study was conducted in two stages. In the first stage, two groups were included: MS patients before the NI (group A) and healthy control subjects (group B). In this stage, groups (A) and (B) were compared (case-control study). In the second stage, group (A) was assessed after the NI, with comparisons made between baseline and final measurements (before-and-after study). In the case-control stage (baseline evaluation), we found significant differences in fatigue scores (p < 0.001), adherence to the MIND diet (p < 0.001), the serum levels of brain-derived neurotrophic factor (BDNF) (p < 0.001), and higher oxidative status in the MS group, with lower levels of reduced glutathione (p < 0.001), reduced/oxidised glutathione ratio (p < 0.001), and elevated levels of lipoperoxidation (p < 0.002) and 8-hydroxy-2'-deoxyguanosine (p < 0.025). The before-and-after intervention stage showed improvements in fatigue scores (p < 0.001) and physical quality-of-life scores (MSQOL-54) (p < 0.022), along with decreases in the serum levels of glial-derived neurotrophic factor (GDNF) (p < 0.041), lipoperoxidation (p < 0.046), and 8-hydroxy-2'-deoxyguanosine (p < 0.05). Consumption of the MIND diet is linked to clinical and biochemical improvement in MS patients.

FK962 protects retinal ganglion cell under hypoxia/reoxygenation: Possible involvement of glial cell line-derived neurotrophic factor signaling pathway

Loss of retinal ganglion cells (RGCs) is the cause of visual impairment and blindness in glaucoma. Previously, our studies showed that FK962 (N-[1-acetylpiperidin-4-yl]-4-fluorobenzamide) promoted neurite elongation in rat RGCs and trigeminal ganglion (TG) cells. In TG cells, glial cell line-derived neurotrophic factor (GDNF) is known to be involved in the mechanism. The purpose of the present study is to investigate whether, 1) FK962 shows an RGC-protective effect under hypoxia/reoxygenation (H/R) and 2) GDNF is involved in the neuroprotective mechanism of FK962. Rat primary retinal cells were cultured under 24-h hypoxia/24-h reoxygenation conditions, with or without FK962, recombinant GDNF, GDNF antibody and RET receptor tyrosine kinase inhibitor, GSK3179106. Cells were co-immunostained with RBPMS and Neurofilament 200 as a RGC marker, and the number of survived RGCs was counted. Results showed H/R treatment decreased the number of survived RGCs. FK962 promoted RGC survival under H/R by a bell-shaped dose response, with the highest RGC-protective effect of 10−8 M. The protective effect was the same level with 10−12 M exogenous GDNF. Addition of GDNF antibody or GSK3179106 counteracted the neuroprotective effect of FK962. From these results, it is suggested that FK962 ameliorates RGC death under H/R, possibly via a GDNF signaling pathway.

Cryogel microcarriers loaded with glial cell line-derived neurotrophic factor enhance the engraftment of primary dopaminergic neurons in a rat model of Parkinson’s disease

Objective.Cryogel microcarriers made of poly(ethylene glycol) diacrylate and 3-sulfopropyl acrylate have the potential to act as delivery vehicles for long-term retention of neurotrophic factors (NTFs) in the brain. In addition, they can potentially enhance stem cell-derived dopaminergic (DAergic) cell replacement strategies for Parkinson's disease (PD), by addressing the limitations of variable survival and poor differentiation of the transplanted precursors due to neurotrophic deprivation post-transplantation in the brain. In this context, to develop a proof-of-concept, the aim of this study was to determine the efficacy of glial cell line-derived NTF (GDNF)-loaded cryogel microcarriers by assessing their impact on the survival of, and reinnervation by, primary DAergic grafts after intra-striatal delivery in Parkinsonian rat brains.Approach.Rat embryonic day 14 ventral midbrain cells were transplanted into the 6-hydroxydopamine-lesioned striatum either alone, or with GDNF, or with unloaded cryogel microcarriers, or with GDNF-loaded cryogel microcarriers.Post-mortem, GDNF and tyrosine hydroxylase immunostaining were used to identify retention of the delivered GDNF within the implanted cryogel microcarriers, and to identify the transplanted DAergic neuronal cell bodies and fibres in the brains, respectively.Main results.We found an intact presence of GDNF-stained cryogel microcarriers in graft sites, indicating their ability for long-term retention of the delivered GDNF up to 4 weeks in the brain. This resulted in an enhanced survival (1.9-fold) of, and striatal reinnervation (density & volume) by, the grafted DAergic neurons, in addition to an enhanced sprouting of fibres within graft sites.Significance.This data provides an important proof-of-principle for the beneficial effects of neurotrophin-loaded cryogel microcarriers on engraftment of cells in the context of cell replacement therapy in PD. For clinical translation, further studies will be needed to assess the impact of cryogel microcarriers on the survival and differentiation of stem cell-derived DAergic precursors in Parkinsonian rat brains.

GDNF facilitates cognitive function recovery following neonatal surgical-induced learning and memory impairment via activation of the RET pathway and modulation of downstream effectors PKMζ and Kalirin in rats

ObjectiveThe aim of this study is to elucidate the underlying mechanism through which glial cell line-derived neurotrophic factor (GDNF) improves cognitive deficits in adults resulting from neonatal surgical interventions. MethodsNewborn Sprague–Dawley rats, regardless of gender, were randomly allocated into seven groups on postnatal day 7 as follows (n=15): (1) Control group (not subjected to anesthesia, surgery, or any pharmaceutical interventions); (2) GDNF group (received intracerebroventricular injection of GDNF); (3) Surgery group (underwent right carotid artery exposure under anesthesia with 3 % sevoflurane); (4) Surgery plus GDNF group; (5) Surgery plus GDNF and type II JAK inhibitor NVP-BBT594 (BBT594) group (administered intraperitoneal injection of BBT594); (6) BBT group; and (7) Surgery plus BBT group. Starting from postnatal day 33, all rats underwent Barnes maze and fear conditioning tests, followed by decapitation under sevoflurane anesthesia for subsequent analyses. The left hemibrains underwent Golgi staining, while the right hemibrains were used for hippocampal protein extraction to assess Protein kinase Mζ (PKMζ) and Kalirin expression through western blotting. ResultsGDNF demonstrated a mitigating effect on spatial learning and memory impairment, as well as context-related fear memory impairment, reductions in dendritic total lengths, and spinal density within the hippocampus induced by surgical intervention. Notably, all of these ameliorative effects of GDNF were reversed upon administration of the RET inhibitor BBT594. Additionally, GDNF alleviated the downregulation of protein expression of PKMζ and Kalirin in the hippocampus of rats subjected to surgery, subsequently reversed by BBT594. ConclusionThe effective impact of GDNF on learning and memory impairment caused by surgical intervention appears to be mediated through the RET pathway. Moreover, GDNF may exert its influence by upregulating the expression of PKMζ and Kalirin, consequently enhancing the development of dendrites and dendritic spines.

Interindividual Variation in Gut Nitrergic Neuron Density Is Regulated By GDNF Levels and ETV1

The size and function of the enteric nervous system (ENS) can vary substantially between individuals. Because ENS function is involved in the etiology of a growing number of common human diseases, understanding mechanisms that regulate ENS variation is important. We analyzed RNAseq data from 41 normal adult human colon biopsies and single-cell RNA-seq data from human and mouse developing gut. To establish cause-consequence relationship we used alleles in mice that allow levels change of the candidate effector molecule in the comparable range to human samples. We used siRNA and primary neuronal cultures to define downstream molecular events and characterized gut functional changes in mice where molecular phenotypes paralleled findings in humans. We found that glial cell line-derived neurotrophic factor (GDNF) levels in the human colon vary about 5-fold and correlate strongly with nitrergic marker expression. In mice, we defined that GDNF levels are regulated via its 3' untranslated region (3' UTR) in the gastrointestinal tract and observed similar correlation between GDNF levels and nitrergic lineage development. We identified miR-9 and miR-133 as evolutionarily conserved candidates for negative regulation of GDNF expression in the gastrointestinal tract. Functionally, an increase in inhibitory nitrergic innervation results in an increase in gastrointestinal tract transit time, stool size, and water content accompanied with modestly reduced epithelial barrier function. Mechanistically, we found that GDNF levels regulate nitrergic lineage development via induction of transcription factor ETV1, corroborated by single-cell gene expression data in human and mouse developing enteric neurons. Our results reveal how normal variation in GDNF levels influence ENS size, composition, and gut function, suggesting a mechanism for well-known interindividual variation among those parameters.

Bioactive Glial-Derived Neurotrophic Factor from a Safe Injectable Collagen-Alginate Composite Gel Rescues Retinal Photoreceptors from Retinal Degeneration in Rabbits.

The management of vision-threatening retinal diseases remains challenging due to the lack of an effective drug delivery system. Encapsulated cell therapy (ECT) offers a promising approach for the continuous delivery of therapeutic agents without the need for immunosuppressants. In this context, an injectable and terminable collagen-alginate composite (CAC) ECT gel, designed with a Tet-on pro-caspase-8 system, was developed as a safe intraocular drug delivery platform for the sustained release of glial-cell-line-derived neurotrophic factor (GDNF) to treat retinal degenerative diseases. This study examined the potential clinical application of the CAC ECT gel, focusing on its safety, performance, and termination through doxycycline (Dox) administration in the eyes of healthy New Zealand White rabbits, as well as its therapeutic efficacy in rabbits with sodium-iodate (SI)-induced retinal degeneration. The findings indicated that the CAC ECT gel can be safely implanted without harming the retina or lens, displaying resistance to degradation, facilitating cell attachment, and secreting bioactive GDNF. Furthermore, the GDNF levels could be modulated by the number of implants. Moreover, Dox administration was effective in terminating gel function without causing retinal damage. Notably, rabbits with retinal degeneration treated with the gels exhibited significant functional recovery in both a-wave and b-wave amplitudes and showed remarkable efficacy in reducing photoreceptor apoptosis. Given its biocompatibility, mechanical stability, controlled drug release, terminability, and therapeutic effectiveness, our CAC ECT gel presents a promising therapeutic strategy for various retinal diseases in a clinical setting, eliminating the need for immunosuppressants.