Rat Brain Cell Cultures Research Articles

The Role of Intracellular Ca2+ and Mitochondrial ROS in Small Aβ1-42 Oligomer-Induced Microglial Death.

Alzheimer's disease (AD) is the most common form of dementia worldwide, and it contributes up to 70% of cases. AD pathology involves abnormal amyloid beta (Aβ) accumulation, and the link between the Aβ1-42 structure and toxicity is of major interest. NMDA receptors (NMDAR) are thought to be essential in Aβ-affected neurons, but the role of this receptor in glial impairment is still unclear. In addition, there is insufficient knowledge about the role of Aβ species regarding mitochondrial redox states in neurons and glial cells, which may be critical in developing Aβ-caused neurotoxicity. In this study, we investigated whether different Aβ1-42 species-small oligomers, large oligomers, insoluble fibrils, and monomers-were capable of producing neurotoxic effects via microglial NMDAR activation and changes in mitochondrial redox states in primary rat brain cell cultures. Small Aβ1-42 oligomers induced a concentration- and time-dependent increase in intracellular Ca2+ and necrotic microglial death. These changes were partially prevented by the NMDAR inhibitors MK801, memantine, and D-2-amino-5-phosphopentanoic acid (DAP5). Neither microglial intracellular Ca2+ nor viability was significantly affected by larger Aβ1-42 species or monomers. In addition, the small Aβ1-42 oligomers caused mitochondrial reactive oxygen species (mtROS)-mediated mitochondrial depolarization, glutamate release, and neuronal cell death. In microglia, the Aβ1-42-induced mtROS overproduction was mediated by intracellular calcium ions and Aβ-binding alcohol dehydrogenase (ABAD). The data suggest that the pharmacological targeting of microglial NMDAR and mtROS may be a promising strategy for AD therapy.

EFFECTS OF PROGENITOR CELL CONDITIONED MEDIA ON THE AMOUNT OF BRAIN CORTEX NEURONS IN A RAT MODEL OF TRAUMATIC BRAIN INJURY

Aim. The purpose of the study was to examine beneficial effect of conditioned media (CM) of progenitor cells of different origin (neurogenic progenitor cells, or NPCs, and adipose-derived mononuclear cells, or AMCs) as a source of mesenchymal multipotent stromal cells (MMSCs) on brain cortex neurons in rats with traumatic brain injury (TBI). Methods. TBI was reproduced in outbred sexually mature male rats by developing the model of free-falling load (50 g) with damage to the left hemisphere of the brain. The rats were injected 3 times with an interval of every other day intraperitoneally with NPCs CM and AMCs CM (dose 0.8 mg by total protein) that were obtained from cell cultures of fetal rat brain and adult rat adipose tissue. On the 5th day after TBI, the morphologic study of brain tissue was performed. Results. The number of neurons in the cortex of rats on the 5th day after TBI in damaged hemisphere as well as in contralateral hemisphere compared to control group decreased by half. Three i.p. injections of NPCs CM or AMCs CM increased the number of neurons in the cortex in both hemispheres in rats of corresponding groups compared to the rats with TBI without additional treatment. Conclusion. Obtained results indicate that CM obtained from NPCs and AMCs have noticeable neuroprotective effect on the damaged neurons and might be considered as an additional mode to treatment of TBI.

Acute and long-term effects of VX in rat brain cell aggregate culture

The contact poison VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) is a chemical warfare agent that is one of the most toxic organophosphorus compounds known. Its primary mechanism of toxic action is through the inhibition of acetylcholinesterase and resultant respiratory paralysis. The majority of work on VX has thus concentrated on its potent anticholinesterase activity and acute toxicity, with few studies investigating potential long-term effects. In this report we describe the effects of VX in aggregating rat brain cell cultures out to 28 days post-exposure. Cholinesterase activity was rapidly inhibited (60 min IC50 = 0.73 +/− 0.27 nM), but recovered towards baseline values over the next four weeks. Apoptotic cell death, as measured using caspase-3 activity was evident only at 100 μM concentrations. Cell type specific enzymatic markers (glutamine synthase, choline acetyltransferase and 2′,3′-cyclic nucleotide 3′-phosphodiesterase) showed no significant changes. Total Akt levels were unchanged, while an increased phosphorylation of this protein was noted only at the highest VX concentration on the first day post-exposure. In contrast, significant and delayed (28 days post-exposure) decreases were noted in vascular endothelial growth factor (VEGF) levels, a protein whose reduced levels are known to contribute to neurodegenerative disorders. These observations may indicate that the long-term effects noted in some survivors of nerve agent intoxication may be due to VX-induced declines in brain VEGF levels.

Mutual Interactions Between GnRH and Kisspeptin in GnRH- and Kiss-1-Expressing Immortalized Hypothalamic Cell Models.

Kisspeptin and gonadotropin-releasing hormone (GnRH) are central regulators of the hypothalamic-pituitary-gonadal axis and control female reproductive functions. Recently established mHypoA-50 and mHypoA-55 cells are immortalized hypothalamic neuronal cell models that originated from the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC) regions of the mouse hypothalamus, respectively. mHypoA-50 or mHypoA-55 cells were stimulated with kisspeptin-10 (KP10) and GnRH, after which the expression of kisspeptin and GnRH was determined. Primary cultures of fetal rat brain cells were also examined. mHypoA-50 and mHypoA-55 cells expressed mRNA for Kiss-1 (which encodes kisspeptin) and GnRH as well as receptors for kisspeptin and GnRH. We found that Kiss-1 mRNA expression was significantly increased in mHypoA-50 AVPV cells by KP10 and GnRH stimulation. Kisspeptin protein expression was also increased by KP10 and GnRH stimulation in these cells. In contrast, GnRH expression was unchanged in mHypoA-50 AVPV cells by KP10 and GnRH stimulation. In mHypoA-55 ARC cells, kisspeptin expression was also significantly increased at the mRNA and protein levels by KP10 and GnRH stimulation; however, GnRH expression was also upregulated by KP10 and GnRH stimulation in these cells. KP10 and estradiol (E2) both increased Kiss-1 gene expression in mHypoA-50 AVPV cells, but combined stimulation with KP10 and E2 did not potentiate their individual effects on Kiss-1 gene expression. On the other hand, E2 did not increase Kiss-1 gene expression in mHypoA-55 ARC cells, and the KP10-induced increase of Kiss-1 gene expression was inhibited in the presence of E2 in these cells. KP10 and GnRH significantly increased c-Fos protein expression in the mHypoA-50 AVPV and mHypoA-55 ARC cell lines. In primary cultures of fetal rat neuronal cells, KP10 significantly increased Kiss-1 gene expression, whereas GnRH significantly increased GnRH gene expression. We found that kisspeptin and GnRH affected Kiss-1- and GnRH-expressing hypothalamic cells and modulated Kiss-1 and/or GnRH gene expression with a concomitant increase in c-Fos protein expression. A mutual- or self-regulatory system might be present in Kiss-1 and/or GnRH neurons in the hypothalamus.

Effect of anti-Müllerian hormone in hypothalamic Kiss-1- and GnRH-producing cell models

Purpose: Anti-Müllerian hormone (AMH) is one of the local factors involved in follicle development. In addition, AMH and its receptor are broadly expressed throughout the body. In this study, we examined how AMH modifies gene expression of Kiss-1 and GnRH. Materials and methods: mHypoA-50 and mHypoA-55 cells were originated from the hypothalamic anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC), respectively, and these cells are known as Kiss-1 (which encodes kisspeptin) expressing cell models. These cells also express gonadotropin-releasing hormone (GnRH) genes. Our experiments were performed useing these cell models. Results: Both mHypoA-50 and mHypoA-55 hypothalamic cells expressed AMH and AMH receptor type 2 (AMHR2). Exogenous AMH failed to alter the expression levels of the Kiss-1 gene in both cell models but significantly increased GnRH gene expression by 1.73 ± 0.2-fold at 100 pM in mHypoA-50 AVPV cells and by 1.74 ± 0.17-fold at 1 nM in mHypoA-55 ARC cells. AMH also augmented GnRH protein expression in both cell models. Similar to the phenomenon observed in the hypothalamic cell lines, 100 pM AMH significantly increased GnRH, but not Kiss-1, mRNA expression in primary cultures of fetal rat brain cells. Kisspeptin-10 (KP10) increased Kiss-1 gene expression in mHypoA-55 ARC cells but this was blocked by AMH. AMH did not alter the expression of the kisspeptin receptor (Kiss1R) or that of neurokinin B or dynorphin A in mHypoA-55 ARC cells. Conclusions: It was demonstrated that AMH participates in hypothalamic-pituitary-gonadal axis control by stimulating GnRH expression. In addition, AMH might be a potent repressor of Kiss-1 gene expression induced by KP10.

Developmental Pb2+-exposure alters KCC₂ and VSCC-β3 subunit expression patterns in the postnatal rat brain and cerebellar granule cell cultures: Implications for disrupted GABA-shifts resulting from neurotoxicant exposures.

Developmental Pb2+-exposure alters KCC₂ and VSCC-β3 subunit expression patterns in the postnatal rat brain and cerebellar granule cell cultures: Implications for disrupted GABA-shifts resulting from neurotoxicant exposures.

A Long Short-Term Memory Neural Network Used to Predict the Exon–Intron Structure of a Gene

Several models of long short-term memory (LSTM) neural networks were constructed. Each model was trained on the complete mouse genome to predict the exon–intron structure of a gene. The performance of the neural networks was compared using a test sample and experimental sequencing data obtained using rat brain cell cultures after treatment with spicing inhibitors.

Apoptosis in Neuronal Populations of C. Elegans through Exposure to Caffeine

Caffeine is the most widely used psychoactive drug in the world and forms a mild dependency in individuals who overuse the drug for an extended period. Other stimulant drugs, including methamphetamines, have been shown to induce apoptosis in the brain’s reward pathways, suggesting that stimulants may lead to apoptosis to lasting neuronal damage. Caffeine has been shown to induce apoptosis in gastric cancer cells in vitro as well as neonatal rat brain and cortical cell cultures. In C. elegans, the homolog of the p‐53 pathway is the CEP‐1 pathway. Caffeine induces apoptosis in human osteoblasts via the p53, Bax, and caspase 3 pathways. However, other studies suggest that caffeine produces inverse effects; caffeine exposure has been reported to increase longevity of Caenorhabditis elegans through activation of the IGF‐1 signaling pathway. Our current data clarifies the relationship between caffeine exposure and CEP‐1 via TG‐12, a C. elegans strain with CEP‐1:: GFP fusion gene.Here we discuss the results of caffeine exposure on TG‐12 worms. Early data indicates that exposure to high levels of caffeine leads to apoptosis in the nerve ring region of the worm. Here we attempt to identify the affected neuronal populations. We plan to further investigate the relationship between CEP‐1 and caffeine exposure in a dose‐dependent fashion via qRT‐PCR.Support or Funding InformationThis work was supported and funded by the Nueva School. The Shen Lab at Stanford University provided lab equipment and OH11061 worms. Worms and technical support were provided by Caenorhabditis Genetics Center (CGC) ‐ College of Biological Sciences

Protein pathway analysis to study development-dependent effects of acute and repeated trimethyltin (TMT) treatments in 3D rat brain cell cultures

Trimethyltin is an organometallic compound, described to be neurotoxic and to trigger neuroinflammation and oxidative stress. Previous studies associated TMT with the perturbation of mitochondrial function, or neurotransmission. However, the mechanisms of toxicity may differ depending on the duration of exposure and on the stage of maturation of brain cells. This study aim at elucidating whether the toxicity pathways triggered by a known neurotoxicant (TMT) differs depending on cell maturation stage or duration of exposure. To this end omics profiling of immature and differentiated 3D rat brain cell cultures exposed for 24 h or 10 days (10-d) to 0.5 and 1 μM of TMT was performed to better understand the underlying mechanisms of TMT associated toxicity.Proteomics identified 55 and 17 proteins affected by acute TMT treatment in immature and differentiated cultures respectively, while 10-day treatment altered 96 proteins in immature cultures versus 353 in differentiated. The results suggest different sensitivity to TMT depending on treatment duration and cell maturation. In accordance with known TMT mechanisms oxidative stress and neuroinflammation was observed after 10-d treatment at both maturation stages, whereas the neuroinflammatory process was more prominent in differentiated cultures than in the immature, no development-dependent difference could be detected for oxidative stress or synaptic neurodegeneration. Pathway analysis revealed that both vesicular trafficking and the synaptic machinery were strongly affected by 10-d TMT treatment in both maturation stages, as was GABAergic and glutamatergic neurotransmission.This study shows that omics approaches combined with pathway analysis constitutes an improved tool-set in elucidating toxicity mechanisms.

In vitro models to study insulin and glucocorticoids modulation of trimethyltin (TMT)-induced neuroinflammation and neurodegeneration, and in vivo validation in db/db mice.

Brain susceptibility to a neurotoxic insult may be increased in a compromised health status, such as metabolic syndrome. Both metabolic syndrome and exposure to trimethyltin (TMT) are known to promote neurodegeneration. In combination the two factors may elicit additive or compensatory/regulatory mechanisms. Combined effects of TMT exposure (0.5-1μM) and mimicked metabolic syndrome-through modulation of insulin and glucocorticoid (GC) levels-were investigated in three models: tridimensional rat brain cell cultures for neuron-glia effects; murine microglial cell line BV-2 for a mechanistic analysis of microglial reactivity; and db/db mice as an in vivo model of metabolic syndrome. In 3D cultures, low insulin condition significantly exacerbated TMT's effect on GABAergic neurons and promoted TMT-induced neuroinflammation, with increased expression of cytokines and of the regulator of intracellular GC activity, 11β-hydroxysteroid dehydrogenase 1 (11β-Hsd1). Microglial reactivity increased upon TMT exposure in medium combining low insulin and high GC. These results were corroborated in BV-2 microglial cells where lack of insulin exacerbated the TMT-induced increase in 11β-Hsd1 expression. Furthermore, TMT-induced microglial reactivity seems to depend on mineralocorticoid receptor activation. In diabetic BKS db mice, a discrete exacerbation of TMT neurotoxic effects on GABAergic neurons was observed, together with an increase of interleukin-6 (IL-6) and of basal 11β-Hsd1 expression as compared to controls. These results suggest only minor additive effects of the two brain insults, neurotoxicant TMT exposure and metabolic syndrome conditions, where 11β-Hsd1 appears to play a key role in the regulation of neuroinflammation and of its protective or neurodegenerative consequences.

Argininosuccinate neurotoxicity and prevention by creatine in argininosuccinate lyase deficiency: An in vitro study in rat three-dimensional organotypic brain cell cultures.

The urea cycle disorder (UCD) argininosuccinate lyase (ASL) deficiency, caused by a defective ASL enzyme, exhibits a wide range of phenotypes, from life-threatening neonatal hyperammonemia to asymptomatic patients, with only the biochemical marker argininosuccinic acid (ASA) elevated in body fluids. Remarkably, even without ever suffering from hyperammonemia, patients often develop severe cognitive impairment and seizures. The goal of this study was to understand the effect on the known toxic metabolite ASA and the assumed toxic metabolite guanidinosuccinic acid (GSA) on developing brain cells, and to evaluate the potential role of creatine (Cr) supplementation, as it was described protective for brain cells exposed to ammonia. We used an in vitro model, in which we exposed three-dimensional (3D) organotypic rat brain cell cultures in aggregates to different combinations of the metabolites of interest at two time points (representing two different developmental stages). After harvest and cryopreservation of the cell cultures, the samples were analyzed mainly by metabolite analysis, immunohistochemistry, and western blotting. ASA and GSA were found toxic for astrocytes and neurons. This toxicity could be reverted in vitro by Cr. As well, an antiapoptotic effect of ASA was revealed, which could contribute to the neurotoxicity in ASL deficiency. Further studies in human ASL deficiency will be required to understand the biochemical situation in the brain of affected patients, and to investigate the impact of high or low arginine doses on brain Cr availability. In addition, clinical trials to evaluate the beneficial effect of Cr supplementation in ASL deficiency would be valuable.

TGF-β1 EXPRESSION BY GLIOMA C6 CELLS IN VITRO

FRBCS was obtained from suspensions of fetal rat brain cells on the 14th (E14) day of gestation. C6glioma cells were cultured for 48h in the presence of FRBCS or FRBCS + anti-TGF-β1 monoclonal antibody. Immunocytochemical staining for TGF-β1 and p53was performed. The proportion of TGF-β1-immunopositive tumor cells in C6glioma cultures was statistically significantly higher than in the control cell cultures of normal fetal rat brain. FRBCS reduced the proportion of TGF-β1-immunopositive tumor cells and increased the proportion of p53-immunopositive cells in C6glioma cultures. In cells cultured with FRBCS + anti-TGF-β1monoclonal antibody, the above effects of FRBCS were abrogated. The obtained results suggest that TGF-β1seems to be responsible for decrease in TGF-β1 expression and increase in p53expression in C6glioma cells treated with FRBCS.

Potential mechanisms of development-dependent adverse effects of the herbicide paraquat in 3D rat brain cell cultures

Exposure to environmental toxicants during vulnerable windows of brain development is suspected to raise the prevalence for neurological dysfunctions at later stages in life. Differentiation processes and changes in morphology, as well as a lack of physiological barriers, might be reasons that render a developing brain more susceptible to neurotoxicants than an adult. However, also the intrinsic capacity of cells to combat toxicant induced cellular stress might differ between the immature- and mature brain. In order to study whether this intrinsic protection capacity differs between immature and maturated brain cells we chose to study the maturation-dependent adverse effects of the known neurotoxicant Paraquat Dichloride (PQ) in 3D rat brain cell cultures. This in vitro system consists of the major brain cell types – neurons, astrocytes, oligodendrocytes and microglia – and over the time in vitro cultured cells undergo differentiation and maturation into a tissue-like organization. PQ was applied repeatedly over ten days in the sub-micromolar range, and effects were evaluated on neurons and glial cells. We observed that despite a higher PQ-uptake in mature cultures, PQ-induced adverse effects on glutamatergic-, GABAergic- and dopaminergic neurons, as assessed by gene expression and enzymatic activity, were more pronounced in immature cultures. This was associated with a stronger astrogliosis in immature- as compared to mature cultures, as well as perturbations of the glutathione-mediated defense against oxidative stress. Furthermore we observed evidence of microglial activation only in mature cultures, whereas immature cultures appeared to down-regulate markers for neuroprotective M2–microglial phenotype upon PQ-exposure. Taken together our results indicate that immature brain cell cultures have less intrinsic capacity to cope with cellular stress elicited by PQ as compared to mature cells. This may render immature brain cells more susceptible to the adverse effects of PQ.

Morphometric characteristics of TGF-β1-positive cells of fetal rat brain in vitro

One of the directions of cell therapy being developed for brain gliomas is the use of the neurogenic stem and progenitor cells (NSCs/NPCs). There are data on the anti-tumor and immunomodulating properties of the NSCs/NPCs the mechanisms of which were not disclosed yet. One of the potential targets for tumor therapy is the transforming growth factor β (TGF-β1) which is thought to be one of the key molecules in the regulation of proliferation, differentiation and cell survival or apoptosis. In the view of available information about the possibility of TGF-β1 production by the mammalian multipotent NSCs/NPCs, the aim of this work was to study the TGF-β1-positive cells in the dynamics of cultivation of fetal brain neurogenic cells as a potential source of anti-tumor or immunomodulating effects of these cells.Material and methods. The fetal rat brain cells on 14th (E14) day of gestation were used as the source for cultivation in standard conditions (DМЕМ + 1 % fetal bovine serum) and studied on the 2nd and 37thday by morphometry and immunocytochemistry.Results. In the fetal rat brain cell cultures, the TGF-β1-positive cells made 22.04 ± 2.33 % and the nestin-positive cells made 49.16 ± 10.60 % of the total cells number. The morphometric parameters of TGF-β1-positive cells exceeded the corresponding values of negative cells (average values of cross-sectional areas of the cytoplasm, cross-sectional areas of the nucleus, nuclear-cytoplasmic ratio). During cultivation the relative amount of TGF-β1-positive cells was slightly decreased 15.27 ± 9.80 % (p = 0.7) and their sizes were increased. On the 37th day of cultivation the sizes of TGF-β1-positive and their nuclei were smaller in the comparison with the TGF-β1-negative cells.Conclusions. The presence of TGF-β1 expression by part of neurogenic cells of fetal rat brain (E14) in vitro was found, which persisted throughout cultivation (~5 weeks). Significant quantitative differences of morphometric parameters of TGF-β1-positive and negative cells were detected.

Ammonium accumulation is a primary effect of 2-methylcitrate exposure in an in vitro model for brain damage in methylmalonic aciduria.

Using 3D organotypic rat brain cell cultures in aggregates we recently identified 2-methylcitrate (2-MCA) as the main toxic metabolite for developing brain cells in methylmalonic aciduria. Exposure to 2-MCA triggered morphological changes and apoptosis of brain cells. This was accompanied by increased ammonium and decreased glutamine levels. However, the sequence and causal relationship between these phenomena remained unclear. To understand the sequence and time course of pathogenic events, we exposed 3D rat brain cell aggregates to different concentrations of 2-MCA (0.1, 0.33 and 1.0mM) from day in vitro (DIV) 11 to 14. Aggregates were harvested at different time points from DIV 12 to 19. We compared the effects of a single dose of 1mM 2-MCA administered on DIV 11 to the effects of repeated doses of 1mM 2-MCA. Pan-caspase inhibitors Z-VAD FMK or Q-VD-OPh were used to block apoptosis. Ammonium accumulation in the culture medium started within few hours after the first 2-MCA exposure. Morphological changes of the developing brain cells were already visible after 17h. The highest rate of cleaved caspase-3 was observed after 72h. A dose-response relationship was observed for all effects. Surprisingly, a single dose of 1mM 2-MCA was sufficient to induce all of the biochemical and morphological changes in this model. 2-MCA-induced ammonium accumulation and morphological changes were not prevented by concomitant treatment of the cultures with pan-caspase inhibitors Z-VAD FMK or Q-VD-OPh: ammonium increased rapidly after a single 1mM 2-MCA administration even after apoptosis blockade. We conclude that following exposure to 2-MCA, ammonium production in brain cell cultures is an early phenomenon, preceding cell degeneration and apoptosis, and may actually be the cause of the other changes observed. The fact that a single dose of 1mM 2-MCA is sufficient to induce deleterious effects over several days highlights the potential damaging effects of even short-lasting metabolic decompensations in children affected by methylmalonic aciduria.

Dynamics of CD133+ cells in cultures of glioma c6 and fetal rat brain under the neurogenic cells supernatant influence

Cellular and molecular similarities between brain tumor stem cells (BTSCs) and normal neurogenic stem cells (NSCs) motivate the search for new methods of treatment of malignant glioma using NSCs. CD133 molecule could be one of the most typical markers of BTSCs and considered as a target for therapy of brain tumors.The aim of this study was to evaluate the effect of rat neurogenic cells supernatant (NCsS) on the content of CD133+ cells in glioma C6 cell cultures.Materials and methods. The cells of rat brain glioma C6 were used as the source for the cultivation; for comparative assessment of tested compound impact on the intact nervous system the fetal rat brain cells on 14th (E14) day of gestation were used. The study was performed in control cultures under standard culture conditions without NCsS adding and tested cultures with adding NCsS (0.10 mg/ml of protein) for 48 hours. NCsS was received from suspensions of rat brain neurogenic cells (E14).Results. CD133-positive cells were 12.05 ± 4.77 % of the total number of cells in C6 glioma culture and 37.36 ± 12.33 % of the total number of cells in fetal rat brain culture. CD133-positive cells had a smaller size than negative cells (average values of cross-sectional area of cells and nucleus) and greater nuclear-cytoplasmic ratio. The cell and nucleus sizes of CD133-positive cells in cell cultures of fetal rat brain were twice larger than sizes of such cells in cultures of glioma C6.Under the conditions of NCsS for 48 hours the reducing in the number of CD133-positive cells in rat glioma C6 cell cultures (2.88 ± 0.41 %) and lack of such effects in cell cultures of fetal rat brain (E14) were found.Conclusion. The morphological differences of CD133-positive cells in glioma C6 cultures and in cell cultures of fetal rat brain (E14) were detected. The decrease of CD133-positive cells in glioma C6 cells culture under the influence of neurogenic cells supernatant was shown.

Surface glycoprotein of Borna disease virus mediates virus spread from cell to cell.

SummaryBorna disease virus (BDV) is a non‐segmented negative‐stranded RNA virus that maintains a strictly neurotropic and persistent infection in affected end hosts. The primary target cells for BDV infection are brain cells, e.g. neurons and astrocytes. The exact mechanism of how infection is propagated between these cells and especially the role of the viral glycoprotein (GP) for cell–cell transmission, however, are still incompletely understood. Here, we use different cell culture systems, including rat primary astrocytes and mixed cultures of rat brain cells, to show that BDV primarily spreads through cell–cell contacts. We employ a highly stable and efficient peptidomimetic inhibitor to inhibit the furin‐mediated processing of GP and demonstrate that cleaved and fusion‐active GP is strictly necessary for the cell‐to‐cell spread of BDV. Together, our quantitative observations clarify the role of Borna disease virus‐glycoprotein for viral dissemination and highlight the regulation of GP expression as a potential mechanism to limit viral spread and maintain persistence. These findings furthermore indicate that targeting host cell proteases might be a promising approach to inhibit viral GP activation and spread of infection.

Maturation dependent susceptibility to the herbicide paraquat in 3D rat brain cell cultures

Maturation dependent susceptibility to the herbicide paraquat in 3D rat brain cell cultures

Mild guanidinoacetate increase under partial guanidinoacetate methyltransferase deficiency strongly affects brain cell development

Among cerebral creatine deficiency syndromes, guanidinoacetate methyltransferase (GAMT) deficiency can present the most severe symptoms, and is characterized by neurocognitive dysfunction due to creatine deficiency and accumulation of guanidinoacetate in the brain. So far, every patient was found with negligible GAMT activity. However, GAMT deficiency is thought under-diagnosed, in particular due to unforeseen mutations allowing sufficient residual activity avoiding creatine deficiency, but enough guanidinoacetate accumulation to be toxic. With poorly known GAA-specific neuropathological mechanisms, we developed an RNAi-induced partial GAMT deficiency in organotypic rat brain cell cultures. As expected, the 85% decrease of GAMT protein was insufficient to cause creatine deficiency, but generated guanidinoacetate accumulation causing axonal hypersprouting and decrease in natural apoptosis, followed by induction of non-apoptotic cell death. Specific guanidinoacetate-induced effects were completely prevented by creatine co-treatment. We show that guanidinoacetate accumulation without creatine deficiency is sufficient to affect CNS development, and suggest that additional partial GAMT deficiencies, which may not show the classical brain creatine deficiency, may be discovered through guanidinoacetate measurement.

Cell type-specific expression and localization of cytochrome P450 isoforms in tridimensional aggregating rat brain cell cultures

Within the Predict-IV FP7 project a strategy for measurement of in vitro biokinetics was developed, requiring the characterization of the cellular model used, especially regarding biotransformation, which frequently depends on cytochrome P450 (CYP) activity. The extrahepatic in situ CYP-mediated metabolism is especially relevant in target organ toxicity. In this study, the constitutive mRNA levels and protein localization of different CYP isoforms were investigated in 3D aggregating brain cell cultures. CYP1A1, CYP2B1/B2, CYP2D2/4, CYP2E1 and CYP3A were expressed; CYP1A1 and 2B1 represented almost 80% of the total mRNA content. Double-immunolabeling revealed their presence in astrocytes, in neurons, and to a minor extent in oligodendrocytes, confirming the cell-specific localization of CYPs in the brain. These results together with the recently reported formation of an amiodarone metabolite following repeated exposure suggest that this cell culture system possesses some metabolic potential, most likely contributing to its high performance in neurotoxicological studies and support the use of this model in studying brain neurotoxicity involving mechanisms of toxication/detoxication.