Glial Fibrillary Acidic Protein Activation Research Articles

Comparison of chronic restraint stress-and lipopolysaccharide-induced mouse models of depression: Behavior, c-Fos expression, and microglial and astrocytic activation

Depression is a mental disease that involves a variety of complex physiological mechanisms. A wide range of methods have therefore been used to establish mouse models of depression, and there are currently many ways to develop such mouse models. The present study aimed to compare the effects of various model induction methods and assesses their different effects. To this end, C57BL/6J mice were divided into three experimental groups: the chronic restraint stress (CRS) group received 6 hours of daily confinement within restraint tubes over a 3-week period; the chronic lipopolysaccharide (C-LPS) administration group received daily intraperitoneal injections of 0.5 mg/kg LPS for 1 week; and the acute LPS (A-LPS) administration group received a singular intraperitoneal injection of 0.83 mg/kg LPS. A corresponding control group was established for each experimental condition. Following mouse model establishment, depression-like behaviors were assessed through the forced swimming and tail suspension tests; anxiety-related behaviors were evaluated using the open field test and elevated plus maze. Furthermore, the expression of the immediate early gene c-Fos, ionized calcium-binding adapter molecule 1 (IBA1), and glial fibrillary acidic protein (GFAP) was examined via immunofluorescence. Longer immobility durations during the forced swimming and tail suspension tests were observed across all model groups (p < 0.05), indicating depression-like behaviors. Furthermore, the CRS and C-LPS group, but not the A-LPS group, showed significant anxiety-like behaviors in the elevated plus maze (p < 0.05). All model groups also exhibited significant increases in both time and distance explored within the central area of the open field test (p < 0.05). The activation of GFAP- and IBA1-positive cells in the cerebral cortex and hippocampus was also markedly pronounced in all experimental groups, suggesting the association of neuroinflammatory responses with induced depressive states. The present findings contribute to our understanding of the pathophysiology of stress-induced and neuroinflammatory-associated depression, and will help researchers to choose suitable depression models for their investigations.

Surveilling brain damage using brain biomarkers in hypoglycemic neonatal calves with diarrhea.

Hypoglycemia is a condition associated with neonatal diarrhea in calves, leading to increased mortality and neurological clinical signs. The aim of the present study was to determine the development of brain damage in hypoglycemic calves with neonatal diarrhea and the diagnostic and prognostic significance of these biomarkers. Ten healthy and 50 hypoglycemic calves with diarrhea were included in the study. Clinical examination, blood gases and complete blood count were performed at admission. Blood serum calcium-binding protein B (S100B), neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), ubiquitin carboxyl-terminal hydrolysis isoenzyme-1 (UCHL-1), activitin A (ACT), adrenomodullin (AM) concentrations, and creatine kinase-BB (CK-BB) enzyme activity were measured using commercial bovine-specific ELISA kits to assess brain damage. Of the hypoglycemic calves enrolled in the study, 13 (26%) survived and 37 (74%) died. In addition, 32 (64%) of the calves had severe acidosis and 24 (48%) had sepsis. S100B, GFAP, UCHL-1, CK-BB (p < 0.001) and NSE (p < 0.05) concentrations were significantly higher in hypoglycemic calves compared to healthy calves, while ACT concentrations were lower. Blood glucose concentration was negatively correlated with serum S100B, GFAP, UCHL-1, and CK-BB enzyme activity and positively correlated with ACT in hypoglycemic calves (p < 0.01). Brain injury biomarkers were not predictive of mortality (p > 0.05). Morever, severe hypoglycemia, severe acidosis and sepsis variables were not found to have sufficient capacity to predict mortality when considered alone or together (p > 0.05). In conclusion, brain damage may develop as a consequence of hypoglycemia in calves. S100B, NSE, GFAP, UCHL-1, ACT, and CK-BB concentrations can be used to diagnose brain damage in hypoglycemic calves. However, the variables of severe hypoglycemia, severe acidosis, and sepsis together with the biomarkers of brain injury have a limited value in predicting the prognosis of neonatal calves with diarrhea.

Histological and immunohistochemical effects of chronic intraperitoneal monosodium glutamate at doses equivalent to human consumption in cerebellar cortex of the adult mice

Background: Monosodium glutamate (MSG), a flavor enhancer, is one of the most widely used commercial food additives. MSG produces oxidative stress in various tissues including cerebellar cortex. There is a paucity if data on the histological and immunohistochemical changes of glial fibrillary acidic protein (GFAP) on chronic administration of MSG at doses equivalent to human consumption (i.e., 40 mg/kg, 60 mg/kg, and 80 mg/kg daily for 3-month duration), hence this study. Aims and Objectives: The aim of the study was to evaluate the histological and immunohistochemical effects produced by MSG at doses equivalent to human consumption (40mg/kg/day, 60 mg/kg/day, and 80 mg/kg/day) in cerebellar cortex of adult mice. Materials and Methods: Study commenced after the Institutional Animal Ethics Committee approval. 40 Swiss-albino mice were randomly divided into four groups. Group 1 served as the negative control and received distilled water i.p. Groups 2, 3, and 4 received MSG at increasing doses. Animals were euthanized at 3 months, cerebellar samples were examined histopathologically and immunohistochemically. Results: Degeneration of the layers of cerebellar cortex in histopathology and reduction in the GFAP activity was observed in immunohistochemistry. Conclusion: MSG due to its wide consumption can cause degenerative changes in the cerebellum.

Histopathological evaluation of IBA-1, GFAP activity in the brain cortex of rats administered cadmium chloride.

Purpose: This study aims to evaluate the changes in brain tissue and blood-brain barrier due to oxidative stress during cadmium (Cd) poisoning by biochemical, histopathological, and immunohistochemical methods. Methods: 170-190 g weighing eight-week-old female Wistar albino rats were divided into two groups (control and experimental), with 7 animals in each group. Experimental group rats were given 2 mg/kg/day powdered cadmium chloride dissolved in water intraperitoneally every day for two weeks. Biochemical, histopathological and immunohistochemical examination was performed. Results: It was seen that brain malondialdehyde (MDA) levels increased significantly, and glutathione (GSH) and catalase (CAT) activity levels decreased. In addition to degeneration in some pyramidal cells and glial cells, deformity, and picnosis in the nucleus, dilation of the meninges and cortex vessels, and inflammation around the blood vessels were observed. An increase was found in ionized calcium binding adaptor molecule 1 (IBA-1) expression in microglia cells and degenerative endothelial cells, and increased glial fibrillary acidic protein (GFAP) expression was observed in astrocytes and degenerate neurons. Conclusions: It has been shown that cadmium toxicity may cause microgliosis and astrogliogenesis by inducing cytokine production due to cell degeneration, vascularity, and inflammation in the brain cortex and by affecting microglia, astrocytes cells.

Effect of two-week continuous epidural administration of 2% lidocaine on mechanical allodynia induced by spinal nerve ligation in rats.

BackgroundLidocaine is an effective against certain types of neuropathic pain. This study aimed to investigate whether timing of initiating continuous epidural infusion of lidocaine affected the glial activation and development of neuropathic pain induced by L5/6 spinal nerve ligation (SNL) in rats.MethodsFollowing L5/6 SNL, rats were epidurally infused 2% lidocaine (drug infusion initiated on days 1, and 7 post SNL model establishment) or saline (saline infusion initiated on day 1 post SNL model establishment) continuously for 14 days. Mechanical allodynia of the hind paw to von Frey filament stimuli was determined prior to surgery, postoperative day 3, and once weekly after SNL model establishment. At 7 days after the infusion of saline or lidocaine ended, spinal activation of proinflammatory cytokines and astrocytes was evaluated immunohistochemically, using antibodies to interleukin-6 (IL-6) and glial fibrillary acidic protein (GFAP).ResultsContinuous epidural administration of 2% lidocaine for 14 days increased the mechanical withdrawal threshold regardless of the difference in timing of initiating lidocaine administration. Epidurally infusing 2% lidocaine inhibited nerve ligation-induced IL-6 and GFAP activation. In the 2% lidocaine infusion group, rats maintained the increased mechanical withdrawal threshold even at 7 days after the discontinuation of 2% lidocaine infusion. ConclusionsContinuous epidural administration of 2% lidocaine inhibited the development of SNL-induced mechanical allodynia and suppressed IL-6 and GFAP activation regardless of the difference in timing of initiating lidocaine administration.

Photoreceptors Degenerate Through Pyroptosis After Experimental Retinal Detachment.

PurposeGasdermin D (GSDMD) is crucial in neuronal pyroptosis. GSDMD-N and GSDMD-C are two subdomains of the protein GSDMD. GSDMD-N is an executor of pyroptosis, and GSDMD-C has an inhibitory effect on pyroptotic cell death. This study evaluated the role of GSDMD in photoreceptor cell pyroptosis caused by retinal detachment (RD).MethodsRD models were established in rats, and GSDMD cleavage was detected by western blotting. The morphology of photoreceptors was assessed by transmission electron microscopy. Some rats were given subretinal injections of recombinant adeno-associated virus 2/8 (rAAV2/8)–GSDMD-C before RD surgery. We documented the expression of caspase-1 and GSDMD-N in retinas by western blot. Levels of IL-1β, TNF-α, and monocyte chemoattractant protein-1 (MCP-1) were detected by quantitative RT-PCR. The membrane integrity of photoreceptors was evaluated by TOTO-3 iodide staining. Retinal function was measured by electroretinography, and the thickness of the outer nuclear layer was also recorded. We measured the activation of glial fibrillary acidic protein (GFAP), F4/80, and ionized calcium binding adaptor molecule 1 (Iba-1) by immunofluorescence.ResultsThe cleavage of GSDMD peaked at 1 day after RD. The administration of rAAV2/8–GSDMD-C reduced the pyroptosis and subsequent apoptosis of photoreceptors and preserved the retinal function after RD. Expression of IL-1, TNF-α, and MCP-1 was decreased in the rAAV2/8–GSDMD-C group. In addition, the activation of GFAP, Iba-1, and F4/80 in retinas was alleviated by administering rAAV2/8–GSDMD-C after RD.ConclusionsGSDMD participates in the pyroptosis of photoreceptor after RD. Overexpression of GSDMD-C may block GSDMD cleavage and attenuate photoreceptor degeneration.

Meta-analysis of human prefrontal cortex reveals activation of GFAP and decline of synaptic transmission in the aging brain

Despite ongoing research efforts, mechanisms of brain aging are still enigmatic and need to be elucidated for a better understanding of age-associated cognitive decline. The aim of this study is to investigate aging in the prefrontal cortex region of human brain in a meta-analysis of transcriptome datasets. We analyzed 591 gene expression datasets pertaining to female and male human prefrontal cortex biopsies of distinct ages. We used hierarchical clustering and principal component analysis (PCA) to determine the influence of sex and age on global transcriptome levels. In sex-specific analysis we identified genes correlating with age and differentially expressed between groups of young, middle-aged and aged. Pathways and gene ontologies (GOs) over-represented in the resulting gene sets were calculated. Potential causal relationships between genes and between GOs were explored employing the Granger test of gene expression time series over the range of ages. The most outstanding results were the age-related decline of synaptic transmission and activated expression of glial fibrillary acidic protein (GFAP) in both sexes. We found an antagonistic relationship between calcium/calmodulin dependent protein kinase IV (CAMK4) and GFAP which may include regulatory mechanisms involving cAMP responsive element binding protein (CREB) and mitogen-activated protein kinase (MAPK, alias ERK). Common to both sexes was a decline in synaptic transmission, neurogenesis and an increased base-level of inflammatory and immune-related processes. Furthermore, we detected differences in dendritic spine morphogenesis, catecholamine signaling and cellular responses to external stimuli, particularly to metal (Zinc and cadmium) ions which were higher in female brains.

IL-33 deficiency causes persistent inflammation and severe neurodegeneration in retinal detachment

BackgroundInterleukin-33 (IL-33) belongs to the IL-1 cytokine family and resides in the nuclei of various cell types. In the neural retina, IL-33 is predominately expressed in Müller cells although its role in health and disease is ill-defined. Müller cell gliosis is a critical response during the acute phase of retinal detachment (RD), and in this study, we investigated if IL-33 was modulatory in the inflammatory and neurodegenerative pathology which is characteristic of this important clinical condition.MethodsRD was induced by subretinal injection of sodium hyaluronate into C57BL/6 J (WT) and IL-33−/− mice and confirmed by fundus imaging and optical coherence tomography (OCT). The expression of inflammatory cytokines, complement components and growth factors was examined by RT-PCR. Retinal neurodegeneration, Müller cell activation and immune cell infiltration were assessed using immunohistochemistry. The expression of inflammatory cytokines in primary Müller cells and bone marrow-derived macrophages (BM-DMs) was assessed by RT-PCR and Cytometric Bead Array.ResultsRD persisted for at least 28 days after the injection of sodium hyaluronate, accompanied by significant cone photoreceptor degeneration. The mRNA levels of CCL2, C1ra, C1s, IL-18, IL-1β, TNFα, IL-33 and glial fibrillary acidic protein (GFAP) were significantly increased at day 1 post-RD, reduced gradually and, with the exception of GFAP and C1ra, returned to the basal levels by day 28 in WT mice. In IL-33−/− mice, RD induced an exacerbated inflammatory response with significantly higher levels of CCL2, IL-1β and GFAP when compared to WT. Sustained GFAP activation and immune cell infiltration was detected at day 28 post-RD in IL-33−/− mice. Electroretinography revealed a lower A-wave amplitude at day 28 post-RD in IL-33−/− mice compared to that in WT RD mice. IL-33−/− mice subjected to RD also had significantly more severe cone photoreceptor degeneration compared to WT counterparts. Surprisingly, Müller cells from IL-33−/− mice expressed significantly lower levels of CCL2 and IL-6 compared with those from WT mice, particularly under hypoxic conditions, whereas IL-33−/− bone marrow-derived macrophages expressed higher levels of inducible nitric oxide synthase, TNFα, IL-1β and CCL2 after LPS + IFNγ stimulation compared to WT macrophages.ConclusionIL-33 deficiency enhanced retinal degeneration and gliosis following RD which was related to sustained subretinal inflammation from infiltrating macrophages. IL-33 may provide a previously unrecognised protective response by negatively regulating macrophage activation following retinal detachment.

HIV-1 Tat Induces Unfolded Protein Response and Endoplasmic Reticulum Stress in Astrocytes and Causes Neurotoxicity through Glial Fibrillary Acidic Protein (GFAP) Activation and Aggregation

HIV-1 Tat is a major culprit for HIV/neuroAIDS. One of the consistent hallmarks of HIV/neuroAIDS is reactive astrocytes or astrocytosis, characterized by increased cytoplasmic accumulation of the intermediate filament glial fibrillary acidic protein (GFAP). We have shown that that Tat induces GFAP expression in astrocytes and that GFAP activation is indispensable for astrocyte-mediated Tat neurotoxicity. However, the underlying molecular mechanisms are not known. In this study, we showed that Tat expression or GFAP expression led to formation of GFAP aggregates and induction of unfolded protein response (UPR) and endoplasmic reticulum (ER) stress in astrocytes. In addition, we demonstrated that GFAP up-regulation and aggregation in astrocytes were necessary but also sufficient for UPR/ER stress induction in Tat-expressing astrocytes and for astrocyte-mediated Tat neurotoxicity. Importantly, we demonstrated that inhibition of Tat- or GFAP-induced UPR/ER stress by the chemical chaperone 4-phenylbutyrate significantly alleviated astrocyte-mediated Tat neurotoxicity in vitro and in the brain of Tat-expressing mice. Taken together, these results show that HIV-1 Tat expression leads to UPR/ER stress in astrocytes, which in turn contributes to astrocyte-mediated Tat neurotoxicity, and raise the possibility of developing HIV/neuroAIDS therapeutics targeted at UPR/ER stress.

HIV-1 Tat Promotes Lysosomal Exocytosis in Astrocytes and Contributes to Astrocyte-mediated Tat Neurotoxicity

Tat interaction with astrocytes has been shown to be important for Tat neurotoxicity and HIV/neuroAIDS. We have recently shown that Tat expression leads to increased glial fibrillary acidic protein (GFAP) expression and aggregation and activation of unfolded protein response/endoplasmic reticulum (ER) stress in astrocytes and causes neurotoxicity. However, the exact molecular mechanism of astrocyte-mediated Tat neurotoxicity is not defined. In this study, we showed that neurotoxic factors other than Tat protein itself were present in the supernatant of Tat-expressing astrocytes. Two-dimensional gel electrophoresis and mass spectrometry revealed significantly elevated lysosomal hydrolytic enzymes and plasma membrane-associated proteins in the supernatant of Tat-expressing astrocytes. We confirmed that Tat expression and infection of pseudotyped HIV.GFP led to increased lysosomal exocytosis from mouse astrocytes and human astrocytes. We found that Tat-induced lysosomal exocytosis was tightly coupled to astrocyte-mediated Tat neurotoxicity. In addition, we demonstrated that Tat-induced lysosomal exocytosis was astrocyte-specific and required GFAP expression and was mediated by ER stress. Taken together, these results show for the first time that Tat promotes lysosomal exocytosis in astrocytes and causes neurotoxicity through GFAP activation and ER stress induction in astrocytes and suggest a common cascade through which aberrant astrocytosis/GFAP up-regulation potentiates neurotoxicity and contributes to neurodegenerative diseases.

Neural stem cell transplantation decreases neuroinflammation in a transgenic mouse model of Alzheimer's disease.

Inflammatory processes are considered to play an important role in the progression of neurodegenerative changes in Alzheimer's disease (AD). A number of studies have reported that inflammatory processes are highly correlated with cognitive deficits in AD-like mice. Transplantation of neural stem cells (NSCs) has been considered as a potential new therapy for the treatment of AD because of its effects in improving cognitive ability. However, NSCs have not been evaluated for their protective effects against inflammatory changes in AD. Here, we injected NSCs into amyloid precursor protein (APP)/PS1 transgenic mice to analyse cognitive function and to measure glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor molecule-1 (Iba-1) and toll-like receptors 4(TLR4) activation. We also quantified TLR-4 pathway-related agents, Aβ concentration and the levels of proinflammatory mediators. Our results showed that in NSC-injected APP/PS1 mice, activation of GFAP, Iba-1, TLR4 and TLR4 pathway-related agents (MyD88, TRIF, P38 MAPK and NF-κB P65) were significantly decreased with decreased expression of proinflammatory mediators (IL-1, IL-6, TNF-α and PGE2). These changes were associated with the amelioration of cognitive deficits, but no difference was found in Aβ concentration. Our results provide novel evidence that NSC transplantation in APP/PS1 mice significantly improved cognitive deficits and was accompanied by the attenuation of inflammatory injury via suppression of glial and TLR4-mediated inflammatory pathway activation. Our data indicate that these pathways may potentially be important therapeutic targets to prevent or delay AD. This study investigated the neuroprotective effect of neural stem cell (NSC) transplantation against Alzheimer's disease (AD) inflammation. We found that NSC treatment in APP/PS1 mice significantly improved cognitive deficits and was accompanied by the attenuation of inflammatory injury via suppression of glial and toll-like receptor 4 (TLR4) activation and its downstream signalling pathways. Our findings indicate that these pathways may be potentially important therapeutic targets to prevent or delay AD.

Glycyrrhizic acid Attenuates Neuroinflammation and Oxidative Stress in Rotenone Model of Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting humans. It is characterized by dopaminergic neurodegeneration, mitochondrial impairment, and oxidative stress, enhanced lipid peroxidation, and induction of pro-inflammatory cytokines. We evaluated the neuroprotective efficacy of glycyrrhizic acid (GA), an active component of licorice, against rotenone-induced-oxidative stress and neuroinflammation in a PD rat model. Since PD is progressive and chronic, we investigated the effect of chronic administration of GA for 4 weeks (50 mg/kg/day), 30 min prior to rotenone administration. Rotenone administration significantly reduced the activity of superoxide dismutase and catalase, and caused the depletion of reduced glutathione. A concomitant increase in the levels of the lipid peroxidation product malondialdehyde was observed. It also significantly enhanced the levels of pro-inflammatory cytokines in the midbrain and elevated the levels of inflammatory mediators such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Immunohistochemical analysis revealed significant increments in ionized calcium-binding adaptor molecule-1 (Iba-1) levels, and in glial fibrillary acidic protein (GFAP) levels, and loss of dopamine neurons in the substantia nigra pars compacta upon rotenone challenge. GA treatment significantly attenuated the dopamine neuron loss and decreased the Iba-1 and GFAP activation induced by the rotenone insult. GA also improved antioxidant enzyme activity, prevented glutathione depletion, inhibited lipid peroxidation, and attenuated induction of pro-inflammatory cytokines. Subsequently, GA attenuated the increased levels of the inflammatory mediators COX-2 and iNOS. In conclusion, GA protects against rotenone-induced-PD. The neuroprotective effects of GA are attributed to its potent antioxidative and anti-inflammatory properties.

MDMA administration during adolescence exacerbates MPTP-induced cognitive impairment and neuroinflammation in the hippocampus and prefrontal cortex

We have recently shown that chronic exposure to 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") of adolescent mice exacerbates dopamine neurotoxicity and neuroinflammatory effects elicited by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in the substantia nigra and striatum at adulthood. The present study investigated whether the amplification of MPTP effects by previous treatment with MDMA extends to the limbic and cortical regions and consequently affects cognitive performance. Mice received MDMA (10mg/kg, twice a day/twice a week) for 9weeks, followed by MPTP (20mg/kg × 4 administrations), starting 2weeks after MDMA discontinuation. Complement type 3 receptor (CD11b) and glial fibrillary acidic protein (GFAP) were evaluated by immunohistochemistry in both the hippocampus and the medial prefrontal cortex (mPFC) to measure microglia and astroglia activation. These neurochemical evaluations were paired with an assessment of cognitive performance by means of the novel object recognition (NOR) and spontaneous alternation tasks. MPTP administration to MDMA-pretreated mice elicited a stronger activation of CD11b and GFAP in both the hippocampus and the mPFC compared with either substance administered alone. Furthermore, NOR performance was lower in MDMA-pretreated mice administered MPTP compared with mice that received either substance alone. These results demonstrate that MDMA-MPTP negative interactions extend to the limbic and cortical regions and may result in cognitive impairment, providing further evidence that exposure to MDMA may amplify the effects of later neurotoxic insults.

Lycium Barbarum Polysaccharides Reduce Neuronal Damage, Blood-Retinal Barrier Disruption and Oxidative Stress in Retinal Ischemia/Reperfusion Injury

Neuronal cell death, glial cell activation, retinal swelling and oxidative injury are complications in retinal ischemia/reperfusion (I/R) injuries. Lycium barbarum polysaccharides (LBP), extracts from the wolfberries, are good for “eye health” according to Chinese medicine. The aim of our present study is to explore the use of LBP in retinal I/R injury. Retinal I/R injury was induced by surgical occlusion of the internal carotid artery. Prior to induction of ischemia, mice were treated orally with either vehicle (PBS) or LBP (1 mg/kg) once a day for 1 week. Paraffin-embedded retinal sections were prepared. Viable cells were counted; apoptosis was assessed using TUNEL assay. Expression levels of glial fibrillary acidic protein (GFAP), aquaporin-4 (AQP4), poly(ADP-ribose) (PAR) and nitrotyrosine (NT) were investigated by immunohistochemistry. The integrity of blood-retinal barrier (BRB) was examined by IgG extravasations. Apoptosis and decreased viable cell count were found in the ganglion cell layer (GCL) and the inner nuclear layer (INL) of the vehicle-treated I/R retina. Additionally, increased retinal thickness, GFAP activation, AQP4 up-regulation, IgG extravasations and PAR expression levels were observed in the vehicle-treated I/R retina. Many of these changes were diminished or abolished in the LBP-treated I/R retina. Pre-treatment with LBP for 1 week effectively protected the retina from neuronal death, apoptosis, glial cell activation, aquaporin water channel up-regulation, disruption of BRB and oxidative stress. The present study suggests that LBP may have a neuroprotective role to play in ocular diseases for which I/R is a feature.

Non-invasive quantification of brain tumor-induced astrogliosis

BackgroundCNS injury including stroke, infection, and tumor growth lead to astrogliosis, a process that involves upregulation of glial fibrillary acidic protein (GFAP) in astrocytes. However, the kinetics of astrogliosis that is related to these insults (i.e. tumor) is largely unknown.ResultsUsing transgenic mice expressing firefly luciferase under the regulation of the GFAP promoter (GFAP-luc), we developed a model system to monitor astrogliosis upon tumor growth in a rapid, non-invasive manner. A biphasic induction of astrogliosis was observed in our xenograft model in which an early phase of activation of GFAP was associated with inflammatory response followed by a secondary, long-term upregulation of GFAP. These animals reveal GFAP activation with kinetics that is in parallel with tumor growth. Furthermore, a strong correlation between astrogliosis and tumor size was observed.ConclusionsOur results suggest that non-invasive, quantitative bioluminescent imaging using GFAP-luc reporter animal is a useful tool to monitor temporal-spatial kinetics of host-mediated astrogliosis that is associated with glioma and metastatic brain tumor growth.

The effect of long-term lactobacilli (lactic acid bacteria) enteral treatment on the central nervous system of growing rats

The aim of this study was to explore the relationship between consumption of large doses of lactic acid bacteria (LAB) and the behaviour and brain morphobiochemistry of normal growing rats. Four groups of rats were treated with LAB cultures twice daily for 6 months. The control group received 1 ml of saline per treatment, while two experimental groups received 1 ml of living bacteria ( Lactobacillus plantarum and Lactobacillus fermentum, respectively) and the remaining group received a heat-treated (inactivated) L. fermentum culture. After 2 and 6 months of treatment, respectively, eight animals from each group were sacrificed, and specimens were taken for further analyses. The behaviour of the rats was evaluated five times in an open-field test at monthly intervals throughout the study. Lactobacilli treatment for 2 months induced changes in the motoric behaviour of the rats. The concentration of the astrocytesoluble and filament glial fibrillary acidic protein (GFAP) decreased in the posterior part of the hemispheres, including the thalamus, hippocampus and cortex of the rats treated with L. fermentum. A greater decrease in filament GFAP (up to 50%) was shown in the group receiving the live form of L. fermentum. In contrast, the GFAP in the live L. plantarum-treated group increased, showing elevated levels of the soluble and filament forms of GFAP in the posterior part of the hemispheres. A 60–66% decrease in the amount of the astrocyte-specific Ca-binding protein S-100b was shown in the posterior parts of the hemispheres and in the hindbrain of rats given LAB for 2 months. Prolonged feeding with LAB for 4 months up to full adulthood led to a further decrease in astrocyte reaction, reflected as an additional decrease in the amount of soluble GFAP and locomotor activity in all experimental groups. The changes in filament GFAP and S-100b appeared to disappear after prolonged feeding (total of 6 months) with LAB. In summary, LAB dietary treatment affected the ontogenetic development of the astrocytes, with the highest intensity observed in the early stages of rat development. It can be postulated that LAB treatment may play a preventive role in neurological diseases by decreasing astrocyte reaction and, consequently, lowering locomotor activity.

Protection against Human Immunodeficiency Virus Type 1 Tat Neurotoxicity by Ginkgo biloba Extract EGb 761 Involving Glial Fibrillary Acidic Protein

Human immunodeficiency virus (HIV)-1 Tat protein is an important pathogenic factor in HIV-associated neuropathogenesis. Despite recent progress, the molecular mechanisms underlying Tat neurotoxicity are still not completely understood. However, few therapeutics have been developed to specifically target HIV infection in the brain. Recent development of an inducible brain-specific Tat transgenic mouse model has made it possible to define the mechanisms of Tat neurotoxicity and evaluate anti-neuroAIDS therapeutic candidates in the context of a whole organism. Herein, we demonstrate that administration of EGb 761, a standardized formulation of Ginkgo biloba extract, markedly protected Tat transgenic mice from Tat-induced developmental retardation, inflammation, death, astrocytosis, and neuron loss. EGb 761 directly down-regulated glial fibrillary acidic protein (GFAP) expression at both protein and mRNA levels. This down-regulation was, at least in part, attributable to direct effects of EGb 761 on the interactions of the AP1 and NF-kappaB transcription factors with the GFAP promoter. Most strikingly, Tat-induced neuropathological phenotypes including macrophage/microglia activation, central nervous system infiltration of T lymphocytes, and oxidative stress were significantly alleviated in GFAP-null/Tat transgenic mice. Taken together, these results provide the first evidence to support the potential for clinical use of EGb 761 to treat HIV-associated neurological diseases. Moreover, these findings suggest for the first time that GFAP activation is directly involved in Tat neurotoxicity, supporting the notion that astrocyte activation or astrocytosis may directly contribute to HIV-associated neurological disorders.

Spinal nerve lesion alters blood–spinal cord barrier function and activates astrocytes in the rat

Alterations in the spinal cord microenvironment in a neuropathic pain model in rats comprising right L-4 spinal nerve lesion were examined following 1, 2, 4 and 10 weeks using albumin and glial fibrillary acidic protein (GFAP) immunoreactivity. Rats subjected to nerve lesion showed pronounced activation of GFAP indicating astrocyte activation, and exhibited marked leakage of albumin, suggesting defects of the blood–spinal cord barrier (BSCB) function in the corresponding spinal cord segment. The intensities of these changes were most prominent in the gray matter of the lesioned side compared to the contralateral cord in both the dorsal and ventral horns. The most marked changes in albumin and GFAP immunoreaction were seen after 2 weeks and persisted with mild intensities even after 10 weeks. Distortion of nerve cells, loss of neurons and general sponginess were evident in the gray matter of the spinal cord corresponding to the lesion side. These nerve cell and glial cell changes was mainly evident in the areas showing leakage of endogenous albumin in the spinal cord. These novel observations indicate that chronic nerve lesion has the capacity to induce a selective increase in local BSCB permeability that could be instrumental in nerve cell and glial cell activation. These findings may be relevant to our current understanding on the pathophysiology of neuropathic pain.

Amyloid precursor protein is involved in staurosporine induced glial differentiation of neural progenitor cells

Staurosporine (STS) has been reported as not only a pro-apoptotic agent, but also a terminal differentiation inducer in several neuroblastoma cell lines. Here, we report involvement of amyloid precursor protein (APP) in a STS induced astrocytic differentiation of human neural progenitor cells (NT-2/D1). We found that STS-treated NT-2/D1 cells expressed astrocyte-specific glial fibrillary acidic protein (GFAP), aspartate transporter, and glutamate transporter-1 with a distinctive astrocytic morphology. STS treatment increased GFAP promoter activity and increased expression and secretion of APP in NT-2/D1 cell culture. Overexpressed APP enhanced GFAP promoter activity and expression of GFAP, while gene silencing of APP by RNA interference decreased GFAP expression. These results indicate involvement of APP in STS induced astrocytic differentiation of NT-2/D1 cells. Furthermore, suppression of ERK1/2 phosphorylation, which is known to regulate APP expression by a MEK1 inhibitor, PD098059, reduced both APP and GFAP expression in STS treated NT-2/D1 cells. Thus, STS may induce astrocytic differentiation of NT-2/D1 by increasing APP levels associate with activation of ERK pathway.

Increased expression of glial fibrillary acidic protein in cerebellum and hippocampus: differential effects on neonatal brain regional acetylcholinesterase following maternal exposure to combined chlorpyrifos and nicotine.

Cigarette smoking and environmental exposure to chlorpyrifos during pregnancy could lead to developmental toxicity in the offspring. In the present study, pregnant female Sprague-Dawley rats (300-350 g) were treated daily with nicotine (1 mg/kg, sc) or chlorpyrifos (0.1 mg/kg, dermal) or a combination of nicotine and chlorpyrifos from gestational days (GD) 4-20. Control animals were treated with saline and ethanol. Male offspring from the mothers treated with nicotine alone gained significantly less weight on postnatal day (PND) 30 as compared to control. On PND 7, there was a significant increase in brain acetylcholinesterase (AChE) activity in pups from nicotine- and chlorpyrifos-treated dams, whereas plasma butyrylcholinesterase (BChE) activity was significantly elevated in pups of mothers treated with either chlorpyrifos alone or pesticide combined with nicotine. On PND 30 there was a significant increase in AChE activity in brainstem and cerebellum in all treated male pups. In female pups on PND 30 there was a significant rise in AChE activity in brainstem of chlorpyrifos alone and in cerebellum of the combination nicotine and chlorpyrifos group. Histopathological evaluation demonstrated an increased neuronal cell death in the cerebellum granular cell layer of female offspring from nicotine or combined nicotine with chlorpyrifos group. A rise in glial fibrillary acidic protein (GFAP) immunostaining was observed in the CA1 subfield of hippocampus and cerebellum on PND 30 in female and male offspring of mothers treated with either nicotine or nicotine in combination with chlorpyrifos, but to a lesser extent in males. Data suggest that maternal exposure to nicotine and chlorpyrifos, alone or in combination, produces differential alterations in brain regional AChE activity and expression of GFAP in cerebellum and hippocampus in offspring on PND 30.