Primary Cortical Cell Cultures Research Articles

Protective Effects of Cannabidiol (CBD) against Qxidative Stress, but Not Excitotoxic-Related Neuronal Cell Damage-An In Vitro Study.

Cannabidiol (CBD) appears to possess some neuroprotective properties, but experimental data are still inconsistent. Therefore, this in vitro study aimed to compare the effects of CBD in a wide range of concentrations on oxidative stress and excitotoxic-related cell damage. Results showed that low concentrations of CBD ameliorated the H2O2-evoked cell damage of primary cortical neuronal cell culture. However, higher concentrations of CBD alone (5-25 μM) decreased the viability of cortical neurons in a concentration-dependent manner and aggravated the toxic effects of hydrogen peroxide (H2O2). Neuroprotection mediated by CBD in primary neurons against H2O2 was not associated with a direct influence on ROS production nor inhibition of caspase-3, but we found protective effects of CBD at the level of mitochondrial membrane potential and DNA fragmentation. However, CBD had no protective effect on the glutamate-induced cell damage of cortical neurons, and in higher concentrations, it enhanced the toxic effects of this cell-damaging factor. Likewise, CBD, depending on its concentration, at least did not affect or even enhance cortical cellular damage exposed to oxygen-glucose deprivation (OGD). Finally, we showed that CBD in submicromolar or low micromolar concentrations significantly protected human neuronal-like SH-SY5Y cells against H2O2- and 6-hydroxydopamine (6-OHDA)-induced cell damage. Our data indicate that CBD has a dual effect on oxidative stress-induced neuronal death-in low concentrations, it is neuroprotective, but in higher ones, it may display neurotoxic activity. On the other hand, in excitotoxic-related models, CBD was ineffective or enhanced cell damage. Our data support the notion that the neuroprotective effects of CBD strongly depend on its concentration and experimental model of neuronal death.

Redox Protein Thioredoxin Mediates Neurite Outgrowth in Primary Cultured Mouse Cerebral Cortical Neurons

Thioredoxin system plays an important role in maintaining the cellular redox balance. Recent evidence suggests that thioredoxin (Trx) system may promote cell survival and neuroprotection. In this study, we explored the role of thioredoxin system in neuronal differentiation using a primary mouse cortical neuronal cell culture. First, Trx and Trx reductase (TrxR) protein levels were analyzed in cultured neurons from 1 to 32 days in vitro (DIV). The result showed that Trx and TrxR protein levels time-dependently increased in the neuron cell culture from 1 to 18 DIV. To establish the role of Trx in neuronal differentiation, Trx gene expression was knockdown in cultured neurons using Trx sgRNA CRISPR/Cas9 technology. Treatment with CRISPR/Cas9/Trx sgRNA decreased Trx protein levels and caused a reduction in dendritic outgrowth and branching of cultured neurons. Then, primary cortical neurons were treated with the Trx inhibitor PX12 to block Trx reducing activity. Treatment with PX12 also reduced dendritic outgrowth and branching. Furthermore, PX12 treatment reduced the ratio of phosphorylated cyclic AMP response element-binding protein (CREB)/total CREB protein levels. To investigate whether CREB phosphorylation is redox regulated, SH-SY5Y cells were treated with H2O2, which reduced phosphorylated CREB protein levels and increased CREB thiol oxidation. However, treatment with CB3, a Trx-mimetic tripeptide, rescued H2O2-decreased CREB phosphorylation. Our results suggest that Trx regulates neuronal differentiation and maturation of primary mouse cortical neurons by targeting CREB neurotrophic pathway. Trx may regulate CREB activation by maintaining the cellular redox balance.

Enhancing c‐fosmRNA Expression in Primary Cortical Cell Cultures with a Dynamic Magnetic Fields Device

Magnetic fields have the potential to impact biological systems and trigger various biological responses. However, the mechanisms underlying dynamic magnetic fields (DMFs), which are created by rotating magnets based on Arago's disk principle and include eddy currents, Lorentz forces, and magnetic fields, are not well understood. This study aims to investigate the effects of DMFs on gene expression in primary cultured cortical cells. To simulate DMFs, rotating magnets were used to confirm magnetic flux density, current density, and Lorentz force. Primary cortical cell cultures were then exposed to moderate‐intensity DMFs with a frequency of 40 Hz for 1 h per day over 3 days. The expression of neuroplasticity‐related immediate early genes, including proto‐oncogene c‐fos, activity‐regulated cytoskeleton‐associated protein (Arc) and brain‐derived neurotrophic factor (BDNF) were quantified. The simulation of DMFs generated a periodic magnetic flux density of up to 131 mT, a periodic current density of up to 1.69 A/m2, and a periodic Lorentz force of up to 0.88 nN in the dish. Exposure to DMFs increased c‐fos mRNA expression in primary cortical cell cultures, but did not affect Arc and BDNF expression. The findings suggest that exposure of DMFs in the gamma frequency range, which may be regulated by voltage‐, mechanical‐, and magnetic flux‐sensitive ion channels, could enhance c‐fos expression in primary cortical cell cultures. The device using rotating magnets has the potential to facilitate the development of a cost‐effective and user‐friendly cell culture system based on the principle of Arago's disk. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Galectin-1 as a marker for microglia activation in the aging brain

Microglia cells, the immune cells residing in the brain, express immune regulatory molecules that have a central role in the manifestation of age-related brain characteristics. Our hypothesis suggests that galectin-1, an anti-inflammatory member of the beta-galactoside-binding lectin family, regulates microglia and neuroinflammation in the aging brain. Through our in-silico analysis, we discovered a subcluster of microglia in the aged mouse brain that exhibited increased expression of galectin-1 mRNA. In our Western blotting experiments, we observed a decrease in galectin-1 protein content in our rat primary cortical cultures over time. Additionally, we found that the presence of lipopolysaccharide, an immune activator, significantly increased the expression of galectin-1 protein in microglial cells. Utilizing flow cytometry, we determined that a portion of the galectin-1 protein was localized on the surface of the microglial cells. As cultivation time increased, we observed a decrease in the expression of activation-coupled molecules in microglial cells, indicating cellular exhaustion. In our mixed rat primary cortical cell cultures, we noted a transition of amoeboid microglial cells labeled with OX42(CD11b/c) to a ramified, branched phenotype during extended cultivation, accompanied by a complete disappearance of galectin-1 expression. By analyzing the transcriptome of a distinct microglial subpopulation in an animal model of aging, we established a correlation between chronological aging and galectin-1 expression. Furthermore, our in vitro study demonstrated that galectin-1 expression is associated with the functional activation state of microglial cells exhibiting specific amoeboid morphological characteristics. Based on our findings, we identify galectin-1 as a marker for microglia activation in the context of aging.

A Three-Dimensional Primary Cortical Culture System Compatible with Transgenic Disease Models, Virally Mediated Fluorescence, and Live Microscopy.

In vitro cell culture models can offer high-resolution and high-throughput experimentation of cellular behaviors. However, in vitro culture approaches often fail to fully recapitulate complex cell processes involving synergistic interactions between heterogeneous neural cell populations and the surrounding neural microenvironment. Here, we describe the formation of a three-dimensional primary cortical cell culture system compatible with live confocal microscopy.

LncRNA Gm16638-201 Inhibits the 14-3-3Ɛ Pathway in the Murine Prefrontal Cortex to Induce Depressive Behaviors.

The dysregulation of certain long non-coding RNAs (lncRNAs) has been considered to be involved in neuropsychiatric disorders such as depression, implying the vital role of these transcripts. We have previously identified many differentially expressed lncRNAs in chronic unpredictable mild stress (CUMS) induced mice. Among them, lncRNA Gm16638-201 was highly expressed in the hippocampus (HIP) of CUMS, but the specific role and the underlying mechanisms remain unclear. Here, we reported that lncRNA Gm16638-201 was highly expressed in the prefrontal cortex (PFC) of CUMS induced depressive mice. Bioinformatic analysis shows that Gm16638-201 is mainly located in the cytoplasm. Nine neurological-related genes (Elmo2, Satb1, Hnrnpul1, Sipa1l3, Mapt, Tada3, Sgip1, IL-16, and StarD5) were predicted to be regulated in cis or trans by Gm16638-201 and involved into the 14-3-3Ɛ neurotrophic signaling pathway. We further confirmed the down-regulation of 14-3-3Ɛ and the nine predicted target genes in the PFC of CUMS mice except for Sgip1 and IL-16. In addition, they were also down-regulated in the primary cortical cell cultures with overexpression of Gm16638-201 constructed using an adenoviral-medicated gene expression system. In conclusion, we found that overexpression of Gm16638-201 negatively regulated several target genes and inhibited the 14-3-3Ɛ pathway in the PFC of CUMS induced depressive mice. This promising result suggests that Gm16638-201 may be a potential novel therapeutic target for depression.

The Cholinergic Pathway and MitoK ATP Induce UCP4 Expression Involved in Neuroprotection of FN Stimulation in Rats

Background Electrical stimulation of the cerebellar fastigial nucleus (FN) reduces the infarct size induced by middle cerebral artery occlusion in rats. FN stimulation confers long‐lasting protection from brain injury; however, its underlying mechanism is not yet understood. We aimed to elucidate the mechanism by which FN stimulation exerts neuroprotection. We hypothesized that the neuroprotective effect of FN stimulation involves activation of cholinergic pathways, which increases reactive oxygen species (ROS) production by opening mitochondrial K + ATP channels, thus leading to an increase in UCP4 (uncoupling protein 4) expression and subsequent neuroprotection. Methods FN stimulation was performed for 1 hour in rats. The UCP4 protein and mRNA levels were measured by western blot, dot blot, and in situ hybridization. Carbachol was applied following UCP4‐promoter tdTomato reporter vector transfection of the rat primary cortical cell culture (in vitro) and rat brain (in vivo). We observed cellular UCP4 expression using fluorescence microscopy. UCP4 expression in the cell culture in response to diazoxide application was determined by a reverse transcription‐polymerase chain reaction and western blotting. Results Whereas FN stimulation increased UCP4 protein and mRNA levels, carbachol administration induced UCP4 expression in vitro and in vivo. The attenuation of this effect by atropine suggests that FN‐induced UCP4 expression involves the cholinergic pathway. The opening of mitochondrial K + ATP channels with diazoxide increased the production of ROS and led to increased UCP4 expression. In contrast, quenching ROS with superoxide dismutase reversed the effect of diazoxide on UCP4 expression. Therefore, the opening of mitochondrial K + ATP channels increased ROS production, which subsequently enhanced UCP4 expression and attenuated ROS generation. Conclusion Neuroprotective effect of FN stimulation involves activation of the cholinergic pathways, which increases ROS production by opening mitochondrial K + ATP channels, leading to increased expression of neuroprotective UCP4.

Non-invasive photobiomodulation treatment in an Alzheimer Disease-like transgenic rat model.

Alzheimer's disease (AD) is the most common form of dementia in the elderly, causing neuronal degeneration and cognitive deficits that significantly impair independence and quality of life for those affected and their families. Though AD is a major neurodegenerative disease with vast avenues of investigation, there is no effective treatment to cure AD or slow disease progression. The present work evaluated the therapeutic effect of long-term photobiomodulation (PBM) treatment with continuous-wave low-level laser on AD and its underlying mechanism.Methods: PBM was implemented for 2 min, 3 times per week for 16 months in 2-month-old transgenic AD rats. A battery of behavioral tests was performed to measure the effect of PBM treatment on cognitive dysfunction in AD rats. The effects of PBM therapy on typical AD pathologies, including amyloid plaques, intracellular neurofibrillary tangles, neuronal loss, neuronal injury, neuronal apoptosis, and neurodegeneration, were then assessed. The underlying mechanisms were measured using immunofluorescence staining, western blotting analysis, mass spectrometry, primary cortical and hippocampal cell cultures, and related assay kits.Results: PBM treatment significantly improved the typical AD pathologies of memory loss, amyloid plaques, tau hyperphosphorylation, neuronal degeneration, spine damage, and synaptic loss. PBM treatment had several mechanistic effects which may explain these beneficial effects, including 1) regulation of glial cell polarization and inhibition of neuroinflammation, 2) preservation of mitochondrial dynamics by regulating fission and fusion proteins, and 3) suppression of oxidative damage to DNA, proteins, and lipids. Furthermore, PBM enhanced recruitment of microglia surrounding amyloid plaques by improving the expression of microglial IL-3Rα and astrocytic IL-3, which implies a potential role of PBM in improving Aβ clearance. Finally, our results implicate neuronal hemoglobin in mediating the neuroprotective effect of PBM, as Hbα knockdown abolished the neuroprotective effect of PBM treatment.Conclusion: Collectively, our data supports the potential use of PBM treatment to prevent or slow the progression of AD and provides new insights into the molecular mechanisms of PBM therapy.

Protective Effects of p-Coumaric Acid Isolated from Vaccinium bracteatum Thunb. Leaf Extract on Corticosterone-Induced Neurotoxicity in SH-SY5Y Cells and Primary Rat Cortical Neurons

Corticosterone (CORT)-induced oxidative stress and neurotoxicity can cause neuronal dysfunction and mental disorders. In the present study, we investigated the effects and mechanism of the HP-20 resin fraction of the water extract of Vaccinium bracteatum leaves (NET-D1602) and its bioactive compound p-coumaric acid on neuronal cell damage in SH-SY5Y cells and primary culture of rat cortical cells. NET-D1602 and p-coumaric acid significantly improved cell viability in CORT-induced neurotoxicity in SH-SY5Y cells and primary cultures of rat cortical cells, and increased the activities of antioxidant enzymes (superoxide dismutase and catalase) against CORT-induced neurotoxicity in SH-SY5Y cells. NET-D1602 and p-coumaric acid increased the phosphorylation levels of ERK1/2 and cAMP response element-binding protein (CREB) in cortical neurons. In addition, CREB phosphorylation by NET-D1602 and p-coumaric acid was dramatically reversed by PKA, c-Raf/ERK, PI3K, and mTOR inhibitors. Lastly, we demonstrated the neuroprotective effects of NET-D1602 (3 and 10 μg/mL) and p-coumaric acid (3 and 10 μM) via increased CREB phosphorylation in CORT-induced neurotoxicity mediated via the ERK1/2, Akt, and mTOR pathways. These results suggest that p-coumaric acid is a potential neuroprotective component of NET-D1602, with the ability to protect against CORT-induced neurotoxicity by regulating ERK1/2, Akt, and mTOR-mediated CREB phosphorylation.

Structurally different anabolic androgenic steroids reduce neurite outgrowth and neuronal viability in primary rat cortical cell cultures

The illicit use of anabolic androgenic steroids (AAS) among adolescents and young adults is a major concern due to the unknown and unpredictable impact of AAS on the developing brain and the consequences of this on mental health, cognitive function and behaviour. The present study aimed to investigate the effects of supra-physiological doses of four structurally different AAS (testosterone, nandrolone, stanozolol and trenbolone) on neurite development and cell viability using an in vitro model of immature primary rat cortical cell cultures. A high-throughput screening image-based approach, measuring the neurite length and number of neurons, was used for the analysis of neurite outgrowth. In addition, cell viability and expression of the Tubb3 gene (encoding the protein beta-III tubulin) were investigated. Testosterone, nandrolone, and trenbolone elicited adverse effects on neurite outgrowth as deduced from an observed reduced neurite length per neuron. Trenbolone was the only AAS that reduced the cell viability as indicated by a decreased number of neurons and declined mitochondrial function. Moreover, trenbolone downregulated the Tubb3 mRNA expression. The adverse impact on neurite development was neither inhibited nor supressed by the selective androgen receptor (AR) antagonist, flutamide, suggesting that the observed effects result from another mechanism or mechanisms of action that are operating apart from AR activation. The results demonstrate a possible AAS-induced detrimental effect on neuronal development and regenerative functions. An impact on these events, that are essential mechanisms for maintaining normal brain function, could possibly contribute to behavioural alterations seen in AAS users.

The CCL2/CCL7/CCL12/CCR2 pathway is substantially and persistently upregulated in mice after traumatic brain injury, and CCL2 modulates the complement system in microglia

Traumatic brain injury (TBI) is the leading cause of death in the global population. Disturbed inflammatory processes after TBI exacerbate secondary brain injury and contribute to unfavorable outcomes. Multiple inflammatory events that accompany brain trauma, such as glial activation, chemokine release, or the initiation of the complement system cascade, have been identified as potential targets for TBI treatment. However, the participation of chemokines in the complement activation remains unknown. Our studies sought to determine the changes in the expression of the molecules involved in the CCL2/CCL7/CCL12/CCR2 pathway in the injured brain and the effect of CCL2, CCL7, and CCL12 (10, 100, and 500 ng/mL) on the classic and lectin complement pathways and inflammatory factors in microglial cell cultures. Brain injury in mice was modeled by controlled cortical impact (CCI). Our findings indicate a time-dependent upregulation of CCL2, CCL7, and CCL12 at the mRNA and protein levels within the cortex, striatum, and/or thalamus beginning 24 h after the trauma. The analysis of the expression of the receptor of the tested chemokines, CCR2, revealed its substantial upregulation within the injured brain areas mainly on the mRNA level. Using primary cortical microglial cell cultures, we observed a substantial increase in the expression of CCL2, CCL7, and CCL12 after 24 h of LPS (100 ng/mL) treatment. CCL2 stimulation of microglia increased the level of IL-1β mRNA but did not influence the expression of IL-18, IL-6, and IL-10. Moreover, CCL2 significantly increased the expression of Iba1, a marker of microglia activation. CCL2 and CCL12 upregulated the expression of C1qa but did not influence the expression of C1ra and C1s1 (classical pathway); moreover, CCL2 increased ficolin A expression and reduced collectin 11 expression (lectin pathway). Additionally, we observed the downregulation of pentraxin 3, a modulator of the complement cascade, after CCL2 and CCL12 treatment. We did not detect the expression of ficolin B, Mbl1, and Mbl2 in microglial cells. Our data identify CCL2 as a modulator of the classical and lectin complement pathways suggesting that CCL2 may be a promising target for pharmacological intervention after brain injury. Moreover, our study provides evidence that CCL2 and two other CCR2 ligands may play a role in the development of changes in TBI.

Assessing Cell Viability Effects of Opioids in Primary Cortical Cells from Rat.

Although the number of studies that have examined the impact of opioids on cell viability is very limited, it has clearly shown that opioids commonly used in the clinic can both decrease neurogenesis and induce cell death. These negative effects induced by opioids are worrying and there is a need for further in-depth investigations addressing the impact of opioids on cell function and cell viability. A useful in vitro approach for studying the effects of opioids on cellular function and viability is using primary cortical cell cultures obtained from embryonic day 17 (E17) rat embryos. These cell cultures contain both neurons and glial cells that provide a more physiologically relevant culture condition when compared to the use of various commercially available cell lines. The primary cortical cells can be cultivated in 96-well plates, treated with various concentrations of opioids, and cell viability functions such as mitochondrial function and membrane integrity can easily be assessed using specific colorimetric assays.

Systematic Quantification of Synapses in Primary Neuronal Culture.

SummaryMost neurological disorders display impaired synaptic connectivity. Hence, modulation of synapse formation may have therapeutic relevance. However, the high density and small size of synapses complicate their quantification. To improve synapse-oriented screens, we analyzed the labeling performance of synapse-targeting antibodies on neuronal cell cultures using segmentation-independent image analysis based on sliding window correlation. When assessing pairwise colocalization, a common readout for mature synapses, overlap was incomplete and confounded by spurious signals. To circumvent this, we implemented a proximity ligation-based approach that only leads to a signal when two markers are sufficiently close. We applied this approach to different marker combinations and demonstrate its utility for detecting synapse density changes in healthy and compromised cultures. Thus, segmentation-independent analysis and exploitation of resident protein proximity increases the sensitivity of synapse quantifications in neuronal cultures and represents a valuable extension to the analytical toolset for in vitro synapse screens.

Screening of tau protein kinase inhibitors in a tauopathy-relevant cell-based model of tau hyperphosphorylation and oligomerization

Tauopathies are a class of neurodegenerative disorders characterized by abnormal deposition of post-translationally modified tau protein in the human brain. Tauopathies are associated with Alzheimer’s disease (AD), chronic traumatic encephalopathy (CTE), and other diseases. Hyperphosphorylation increases tau tendency to aggregate and form neurofibrillary tangles (NFT), a pathological hallmark of AD. In this study, okadaic acid (OA, 100 nM), a protein phosphatase 1/2A inhibitor, was treated for 24h in mouse neuroblastoma (N2a) and differentiated rat primary neuronal cortical cell cultures (CTX) to induce tau-hyperphosphorylation and oligomerization as a cell-based tauopathy model. Following the treatments, the effectiveness of different kinase inhibitors was assessed using the tauopathy-relevant tau antibodies through tau-immunoblotting, including the sites: pSer202/pThr205 (AT8), pThr181 (AT270), pSer202 (CP13), pSer396/pSer404 (PHF-1), and pThr231 (RZ3). OA-treated samples induced tau phosphorylation and oligomerization at all tested epitopes, forming a monomeric band (46–67 kDa) and oligomeric bands (170 kDa and 240 kDa). We found that TBB (a casein kinase II inhibitor), AR and LiCl (GSK-3 inhibitors), cyclosporin A (calcineurin inhibitor), and Saracatinib (Fyn kinase inhibitor) caused robust inhibition of OA-induced monomeric and oligomeric p-tau in both N2a and CTX culture. Additionally, a cyclin-dependent kinase 5 inhibitor (Roscovitine) and a calcium chelator (EGTA) showed contrasting results between the two neuronal cultures. This study provides a comprehensive view of potential drug candidates (TBB, CsA, AR, and Saracatinib), and their efficacy against tau hyperphosphorylation and oligomerization processes. These findings warrant further experimentation, possibly including animal models of tauopathies, which may provide a putative Neurotherapy for AD, CTE, and other forms of tauopathy-induced neurodegenerative diseases.

Microglial-specific depletion of TAK1 is neuroprotective in the acute phase after ischemic stroke

Transforming growth factor-β-activated kinase 1 (TAK1) is upregulated after cerebral ischemia and contributes to an aggravation of brain injury. TAK1 acts as a key regulator of NF-ΚB and the MAP kinases JNK and p38 and modulates post-ischemic neuroinflammation and apoptosis. Microglia are the main TAK1-expressing immunocompetent cells of the brain. However, little is known about the function and regulation of microglial TAK1 after cerebral ischemia. Tamoxifen-dependent conditional depletion of TAK1 in microglial cells was induced in Cx3cr1creER-Tak1fl/fl mice. The creER-negative Tak1fl/fl mice and vehicle-treated (corn oil) mice served as control groups. A transient intraluminal middle cerebral artery occlusion of 30 min followed by 6 h and 72 h of reperfusion was performed in male mice. Oxygen-glucose-deprivation (OGD) was performed with primary cortical glial cell cultures to examine the effect of microglial-specific and general (5Z-7-Oxozeaenol) TAK1 inhibition after different reperfusion times (1 h, 6 h, and 72 h). Cx3cr1creER-Tak1fl/fl mice showed reduced infarct sizes and improved neurological outcomes compared to the control group. The mRNA and protein levels of pro-inflammatory Il1b/IL-1β and Tnf/TNF-α in the peri-infarct zones of microglial-specific TAK1-depleted mice were significantly reduced. Furthermore, TAK1 depletion in vitro led to reduced cell death rates after OGD. Moreover, hypoxia-mediated activation of TAK1 and its downstream signalling proteins, JNK and p38, were dampened by microglial TAK1 depletion. In contrast, 5Z-7-Oxozeaenol-induced pharmacological inhibition of TAK1 completely diminished MAPK-signalling including the kinases JNK and p38 in all cells. Microglial TAK1 depletion abrogates post-ischemic neuroinflammation and apoptosis in the acute phase, hence might be considered as a potential target in the treatment of cerebral hypoxia.Key messagesTAK1 is activated after cerebral ischemia and induces MAP kinases p38 and JNK.Activated TAK1 increases apoptosis rate and the level pro-inflammatory cytokines IL-1β and TNF-α.Microglial cells seem to be the main source of TAK1-mediated post-ischemic neuroinflammation.Microglial-specific TAK1-depletion mediates sustainable neuroprotective effects, which might be superior to global TAK1 inhibition.

Aminothioneine activates BDNF expression and enhances learning and memory in mice.

The previous study demonstrated that hot water extract of golden oyster mushrooms (Aminothioneine®) and ergothioneine, which is a hydrophilic antioxidant and contained at high levels in golden oyster mushrooms, increased neuronal differentiation in the hippocampal dentate gyrus of mice and have antidepressant-like effects in mice. Here, we investigated the effect of Aminothioneine on BDNF expression in primary cultures of cortical cells and learning and memory in mice. In primary cultures of rat cortical cells, Aminothioneine, but not ergothioneine, significantly increased expression levels of BDNF mRNA. Aminothioneine also increased the levels of BDNF expression in the hippocampus of mice. Aminothioneine significantly increased freezing behavior in the test session of the contextual fear conditioning test. In the test session of the novel object location recognition test, Aminothioneine-administered mice spent more time exploring the object at the novel location. Taken together, Aminothioneine increased expression levels of BDNF in cultured neurons and hippocampus of mice. Also, Aminothioneine enhances learning and memory in mice. Because it has been reported that higher expression levels of BDNF are associated with slower cognitive decline during aging, Aminothioneine could act as a memory stabilizer in an aging brain.

In vitro cellular uptake and neuroprotective efficacy of poly-arginine-18 (R18) and poly-ornithine-18 (O18) peptides: critical role of arginine guanidinium head groups for neuroprotection.

We have previously demonstrated that Cationic Arginine-Rich Peptides (CARPs) and in particular poly-arginine-18 (R18; 18-mer of arginine) exhibit potent neuroprotective properties in both in vitro and in vivo neuronal injury models. Based on the current literature, there is a consensus that arginine residues by virtue of their positive charge and guanidinium head group is the critical element for imparting CARP neuroprotective properties and their ability to traverse cell membranes. This study examined the importance of guanidinium head groups in R18 for peptide cellular uptake, localization, and neuroprotection. This was achieved by using poly-ornithine-18 (O18; 18-mer of ornithine) as a control, which is structurally identical to R18, but possesses amino head groups rather than guanidino head groups. Epifluorescence and confocal fluorescence microscopy was used to examine the cellular uptake and localization of the FITC-conjugated R18 and O18 in primary rat cortical neurons and SH-SY5Y human neuroblastoma cell cultures. An in vitro cortical neuronal glutamic acid excitotoxicity model was used to compare the effectiveness of R18 and O18 to inhibit cell death and intracellular calcium influx, as well as caspase and calpain activation. Fluorescence imaging studies revealed cellular uptake of both FITC-R18 and FITC-O18 in neuronal and SH-SY5Y cells; however, intracellular localization of the peptides differed in neurons. Following glutamic acid excitotoxicity, only R18 was neuroprotective, prevented caspases and calpain activation, and was more effective at reducing neuronal intracellular calcium influx. Overall, this study demonstrated that for long chain cationic poly-arginine peptides, the guanidinium head groups provided by arginine residues are an essential requirement for neuroprotection but are not required for entry into neurons.

EPO and TMBIM3/GRINA Promote the Activation of the Adaptive Arm and Counteract the Terminal Arm of the Unfolded Protein Response after Murine Transient Cerebral Ischemia.

Ischemic stroke is known to cause the accumulation of misfolded proteins and loss of calcium homeostasis leading to impairment of endoplasmic reticulum (ER) function. The unfolded protein response (UPR) is an ER-located and cytoprotective pathway that aims to resolve ER stress. Transmembrane BAX inhibitor-1 motif-containing (TMBIM) protein family member TMBIM3/GRINA is highly expressed in the brain and mostly located at the ER membrane suppressing ER calcium release by inositol-1,4,5-trisphosphate receptors. GRINA confers neuroprotection and is regulated by erythropoietin (EPO) after murine cerebral ischemia. However, the role of GRINA and the impact of EPO treatment on the post-ischemic UPR have not been elucidated yet. We subjected GRINA-deficient (Grina−/−) and wildtype mice to transient (30 min) middle cerebral artery occlusion (tMCAo) followed by 6 h or 72 h of reperfusion. We administered EPO or saline 0, 24 and 48 h after tMCAo/sham surgery. Oxygen–glucose deprivation (OGD) and pharmacological stimulation of the UPR using Tunicamycin and Thapsigargin were carried out in primary murine cortical mixed cell cultures. Treatment with the PERK-inhibitor GSK-2606414, IRE1a-RNase-inhibitor STF-083010 and EPO was performed 1 h prior to either 1 h, 2 h or 3 h of OGD. We found earlier and larger infarct demarcations in Grina−/− mice compared to wildtype mice, which was accompanied by a worse neurological outcome and an abolishment of EPO-mediated neuroprotection after ischemic stroke. In addition, GRINA-deficiency increased apoptosis and the activation of the corresponding PERK arm of the UPR after stroke. EPO enhanced the post-ischemic activation of pro-survival IRE1a and counteracted the pro-apoptotic PERK branch of the UPR. Both EPO and the PERK-inhibitor GSK-2606414 reduced cell death and regulated Grina mRNA levels after OGD. In conclusion, GRINA plays a crucial role in post-ischemic UPR and the use of both GSK-2606414 and EPO might lead to neuroprotection.

Nanogroove-Enhanced Hydrogel Scaffolds for 3D Neuronal Cell Culture: An Easy Access Brain-on-Chip Model.

In order to better understand the brain and brain diseases, in vitro human brain models need to include not only a chemically and physically relevant microenvironment, but also structural network complexity. This complexity reflects the hierarchical architecture in brain tissue. Here, a method has been developed that adds complexity to a 3D cell culture by means of nanogrooved substrates. SH-SY5Y cells were grown on these nanogrooved substrates and covered with Matrigel, a hydrogel. To quantitatively analyze network behavior in 2D neuronal cell cultures, we previously developed an automated image-based screening method. We first investigated if this method was applicable to 3D primary rat brain cortical (CTX) cell cultures. Since the method was successfully applied to these pilot data, a proof of principle in a reductionist human brain cell model was attempted, using the SH-SY5Y cell line. The results showed that these cells also create an aligned network in the 3D microenvironment by maintaining a certain degree of guidance by the nanogrooved topography in the z-direction. These results indicate that nanogrooves enhance the structural complexity of 3D neuronal cell cultures for both CTX and human SH-SY5Y cultures, providing a basis for further development of an easy access brain-on-chip model.

Screening inducers of neuronal BDNF gene transcription using primary cortical cell cultures from BDNF-luciferase transgenic mice

Brain-derived neurotrophic factor (BDNF) is a key player in synaptic plasticity, and consequently, learning and memory. Because of its fundamental role in numerous neurological functions in the central nervous system, BDNF has utility as a biomarker and drug target for neurodegenerative and neuropsychiatric disorders. Here, we generated a screening assay to mine inducers of Bdnf transcription in neuronal cells, using primary cultures of cortical cells prepared from a transgenic mouse strain, specifically, Bdnf-Luciferase transgenic (Bdnf-Luc) mice. We identified several active extracts from a library consisting of 120 herbal extracts. In particular, we focused on an active extract prepared from Ginseng Radix (GIN), and found that GIN activated endogenous Bdnf expression via cAMP-response element-binding protein-dependent transcription. Taken together, our current screening assay can be used for validating herbal extracts, food-derived agents, and chemical compounds for their ability to induce Bdnf expression in neurons. This method will be beneficial for screening of candidate drugs for ameliorating symptoms of neurological diseases associated with reduced Bdnf expression in the brain, as well as candidate inhibitors of aging-related cognitive decline.