Brain Glial Fibrillary Acidic Protein Research Articles

The effect of repeated transcranial magnetic stimulation combined with cognitive rehabilitation training on post-stroke cognitive impairment.

The aim of this study was to explore the effect of repetitive transcranial magnetic stimulation (rTMS) combined with cognitive rehabilitation training on post-stroke cognitive impairment (PSCI). We retrospectively reviewed clinical data from 119 patients with PSCI admitted to our hospital from December 2021 to April 2023, of which 58 received pure cognitive rehabilitation training (control group) and 61 received rTMS combined with cognitive rehabilitation training (observation group). We calculated measures of cognitive function rehabilitation, daily living activity abilities, latency and amplitude of P300 wave of evoked potential, and serum biochemical index levels before and after the intervention in the two groups. After the intervention, the scores of the Montreal Cognitive Assessment (MoCA) scale and Rivermead behavioral memory test (RBMT) had improved in the two groups. Also, the Modified Barthel Index (MBI) scores of the two groups increased after the intervention. The P300 wave latencies in both groups decreased and their amplitudes increased after the intervention. The levels of serum neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) in the two groups were higher, and the levels of brain glial fibrillary acidic protein (GFAP) were lower after the intervention. All these improvements were more marked in the observation group than in the control group (all p<0.05). Compared with simple cognitive rehabilitation training, the training combined with rTMS was more effective at restoring cognitive function, improving daily living activity abilities, and improving the treatment outcome of patients with PSCI.

Mouse Adapted SARS-CoV-2 (MA10) Viral Infection Induces Neuroinflammation in Standard Laboratory Mice.

Increasing evidence suggests that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection impacts neurological function both acutely and chronically, even in the absence of pronounced respiratory distress. Developing clinically relevant laboratory mouse models of the neuropathogenesis of SARS-CoV-2 infection is an important step toward elucidating the underlying mechanisms of SARS-CoV-2-induced neurological dysfunction. Although various transgenic models and viral delivery methods have been used to study the infection potential of SARS-CoV-2 in mice, the use of commonly available laboratory mice would facilitate the study of SARS-CoV-2 neuropathology. Herein we show neuroinflammatory profiles of immunologically intact mice, C57BL/6J and BALB/c, as well as immunodeficient (Rag2-/-) mice, to a mouse-adapted strain of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 (MA10)). Our findings indicate that brain IL-6 levels are significantly higher in BALB/c male mice infected with SARS-CoV-2 MA10. Additionally, blood-brain barrier integrity, as measured by the vascular tight junction protein claudin-5, was reduced by SARS-CoV-2 MA10 infection in all three strains. Brain glial fibrillary acidic protein (GFAP) mRNA was also elevated in male C57BL/6J infected mice compared with the mock group. Lastly, immune-vascular effects of SARS-CoV-2 (MA10), as measured by H&E scores, demonstrate an increase in perivascular lymphocyte cuffing (PLC) at 30 days post-infection among infected female BALB/c mice with a significant increase in PLC over time only in SARS-CoV-2 MA10) infected mice. Our study is the first to demonstrate that SARS-CoV-2 (MA10) infection induces neuroinflammation in laboratory mice and could be used as a novel model to study SARS-CoV-2-mediated cerebrovascular pathology.

Ethoprophos induces rats' brain injury and neurobehavioral impairment via transcriptional activation of glial fibrillary acidic protein and tubulin-associated unit even at the threshold inhibition of acetylcholinesterase: A 90-days study

Ethoprophos, a common organophosphate nematicide, has adverse effects on the nervous system. However, the specific mechanism of its neurotoxicity is unclear. Here, we have studied the possible involvement of brain glial fibrillary acidic protein and tubulin-associated unit in the neurotoxicity mechanism of ethoprophos, even at the threshold inhibition of acetylcholinesterase. The adult male rats were divided into four groups ( n = 8/group), including the control and exposed groups that were orally received ethoprophos at the low (0.56 mg/kg), median (1.12 mg/kg), and high doses (2.24 mg/kg) for 90 days. Sub-chronic exposure to ethoprophos exhibited a significant decline in the brain activity and mRNA gene expression of acetylcholinesterase, while the levels of dopamine and serotonin were markedly increased at the medium and high doses ( p < 0.01). Ethoprophos increased the anxiety-like behavior in rats subjected to the open field quiz and induced many histopathological alterations in the brain. Furthermore, ethoprophos markedly ( p < 0.05) increased malondialdehyde and nitric oxide levels, while the glutathione content, together with the activities of glutathione peroxidase, glutathione-S-transferase, superoxide dismutase, and catalase were decreased in a dose-dependent manner. Additionally, there was a dose-dependent up-regulation in the mRNA gene expression of brain glial fibrillary acidic protein and tubulin-associated unit in the ethoprophos-exposed rats ( p < 0.05). The obtained data deliver the initial demonstration about the involvement of this up-regulation in the neurotoxicity mechanism of ethoprophos and may use as a biomarker for organophosphate-induced neurodegeneration. • Ethoprophos is a commonly used organophosphate nematicide. • Sub-chronic exposure to ethoprophos elicited oxidative injury in the rat's brain. • Ethoprophos declined the brain activity and mRNA gene expression of AChE. • Ethoprophos increased the catecholamine levels and induced neurobehavioral disorder. • Ethoprophos up-regulated GFAP and TAU mRNA levels at the AChE threshold inhibition.

Di(2-ethylhexyl) adipate plasticizer triggers hepatic, brain, and cardiac injury in rats: Mitigating effect of Peganum harmala oil

Di(2-ethylhexyl) adipate (DEHA) is a widely used plasticizer and prevalent environmental contaminant. In this study, DEHA concentrations in the milk, cheese, and butter samples wrapped with food-grade commercial polyethylene films and stored at 4 °C for 30 days were detected using gas chromatographic analysis. Also, the effects of exposure to a high dose of DEHA for a long duration on the liver, brain, and heart of Wistar rats were assessed. Besides, the possible beneficial effect of Peganum harmala oil (PGO), in relieving DEHA induced adverse effects was explored. For this purpose, four groups (8 rats/group) were orally given physiological saline, PGO (320 mg/kg bwt), DEHA (2000 mg/kg bwt), or PGO + DEHA for 60 days. The results revealed that the DEHA concentrations in the tested dairy products were ordered as follows: (butter > cheese > milk). Notably, the detected levels in butter were higher than the specific migration limit in foods. DEHA induced a significant increase in the serum levels of glucose, alanine transaminase, aspartate transaminase, acetylcholine esterase, creatine kinase–myocardium bound, malondialdehyde, tumor necrosis factor-α, and interleukin-1β. But, significant hypoproteinemia, hypoalbuminemia, hypoglobulinemia, and hypocholesterolemia were evident following DEHA exposure. A significant reduction in the serum level of superoxide dismutase, reduced glutathione, and brain-derived neurotrophic factor was recorded. Besides, a significant downregulation in hepatic CYP2E1, brain glial fibrillary acidic protein, and cardiac troponin I gene expression was noticed. Moreover, DEHA exposure induced a significant decrease in Bcl-2 immunolabeling, but Caspase-3 immunoexpression was increased. On the contrary, PGO significantly recused DEHA injurious impacts. Therefore, PGO could represent a promising agent for preventing DEHA-induced hepatotoxicity, neurotoxicity, and cardiotoxicity.

Sex differences in T cell immune responses, gut permeability and outcome after ischemic stroke in aged mice

IntroductionStroke is a disease that presents with well-known sex differences. While women account for more stroke deaths, recent data show that after adjusting for age and pre-stroke functional status, mortality is higher in men. Immune responses are key determinants of stroke outcome and may differ by sex. This study examined sex differences in central and peripheral T cell immune responses, systemic effects on gut permeability and microbiota diversity and behavioral outcomes after stroke in aged mice. We hypothesized that there are sex differences in the immune response to stroke in aged animals. MethodsC57BL/6CR mice (20–22 months) were subjected to 60 min middle cerebral artery occlusion, or sham surgery. T cells were quantified in brain and blood at 3, 7 and 15 days (d) post-stroke by flow cytometry. Peripheral effects on gut permeability and microbiota diversity, as well as neurological function were assessed up to 14 d, and at 21 d (cognitive function) post-stroke. Brain glial fibrillary acidic protein (GFAP) expression was evaluated at 42 d post-stroke. Results and discussionMortality (50% vs 14%, p < 0.05) and hemorrhagic transformation (44% vs 0%) were significantly higher in males than in females. No difference in infarct size at 3d were observed. Peripherally, stroke induced greater gut permeability of FITC-dextran in males at d3 (p < 0.05), and non-reversible alterations in microbiota diversity in males. Following the sub-acute phase, both sexes demonstrated a time-dependent increase of CD4+ and CD8+ T cells in the brain, with significantly higher levels of CD8+ T cells and Regulatory T cells in males at d15 (p < 0.01). Aged males demonstrated greater neurological deficits up to d5 and impaired sensorimotor function up to d15 when assessed by the corner asymmetry test (p < 0.001 and p < 0.01, respectively). A trend in greater cognitive decline was observed at d21 in males. Increased GFAP expression in the ischemic hemisphere, indicating astroglial activation and gliosis, was demonstrated in both males and females 42d post-stroke. Our findings indicate that despite a similar initial ischemic brain injury, aged male mice experience greater peripheral effects on the gut and ongoing central neuroinflammation past the sub-acute phase after stroke.

Role of citicoline as a protective agent on toluene-induced toxicity in rats

Background/aim Toluene is used as an organic solvent; it has toxic effects on liver, renal, and neurological tissues. Citicoline has antioxidant effects. The aim of this study was to investigate the protective effect of citicoline against toluene-induced toxicity in rats. Material and methods A total of 24 rats were divided in four equal groups with six rats each. Rats in group 1 were the control. Rats in group 2 were exposed to toluene intraperitoneally at 900 mg/kg. Rats in group 3 were exposed to toluene 900 mg/kg in combination with citicoline at 150 mg/kg orally. The rats in group 4 were exposed to toluene 900 mg/kg in combination with citicoline 300 mg/kg orally. All treatments were used daily for 6 days. All rats were killed by decapitation. Tissue sections were stained with routine histological methods and examined under light microscope. In addition, sections were immunohistochemically staining with caspase-3 for liver and renal tissues and glial fibrillary acidic protein (GFAP) for brain tissue, and area percentage of positivity was measure by image analysis system. Results Histopathological and immunomorphometric studies of GFAP in brain and caspase-3 in liver and kidney were done. Toluene-treated groups showed vacuolar degeneration of hepatocytes and epithelial lining of renal tubules, neuronal damage, and neurodegeneration. There was an increase in caspase-3 in liver and kidney, which show marked increase in control positive rats that treated with toluene alone, but when large dose of citicoline 300 mg was added to toluene, the area percentage of caspase-3 was markedly decreased in liver and kidney. In addition, GFAP expression in brain tissue was decreased in toluene-treated control positive group, which then increased when treated with citicoline especially with a large dose. Conclusion The results of this study indicate that citicoline treatment can protect against toluene-induced toxicity in rats.

Astrocyte heterogeneity across the brain and spinal cord occurs developmentally, in adulthood and in response to demyelination.

Astrocytes have emerged as essential regulators of function and response to injury in the brain and spinal cord, yet very little is known about regional differences that exist. Here we compare the expression of key astroglial markers (glial fibrillary acidic protein (GFAP) and Aldehyde Dehydrogenase-1 Family Member L1 (ALDH1L1)) across these disparate poles of the neuraxis, tracking their expression developmentally and in the context of demyelination. In addition, we document changes in the astrocyte regulatory cytokine interleukin 6 (IL-6), and its signaling partner signal transducer and activator of transcription 3 (STAT3), in vivo and in vitro. Results demonstrate that GFAP expression is higher in the developing and adult spinal cord relative to brain. Comparisons between GFAP and ALDH1L1 expression suggest elevations in spinal cord GFAP during the early postnatal period reflect an accelerated appearance of astrocytes, while elevations in adulthood reflect higher expression by individual astrocytes. Notably, increases in spinal cord compared to whole brain GFAP were paralleled by higher levels of IL-6 and STAT3. Equivalent elevations in GFAP, GFAP/ALDH1L1 ratios, and in IL-6, were observed in primary astrocyte cultures derived from spinal cord compared to cortex. Also, higher levels of GFAP were observed in the spinal cord compared to the brain after focal demyelinating injury. Altogether, these studies point to key differences in astrocyte abundance and the expression of GFAP and IL-6 across the brain and spinal cord that are positioned to influence regional specialization developmentally and responses occurring in the context of injury and disease.

Effect of undifferentiated versus hepatogenic partially differentiated mesenchymal stem cells on hepatic and cognitive functions in liver cirrhosis.

Liver cirrhosis is the outcome of chronic liver injury. The current study aimed to investigate the therapeutic effect of undifferentiated mesenchymal stem cells versus in vitro partially differentiated mesenchymal stem cells on liver cirrhosis and hepatic encephalopathy. 50 adult male albino rats constituted the animal model and were divided into the following groups: control, thioacetamide, undifferentiated mesenchymal stem cells and hepatocyte growth factor-differentiated mesenchymal stem cells groups. Cognitive assessment was achieved by open field test and Y-maze task. We measured serum alanine aminotransferase, albumin and transforming growth factor-beta1, gene expression of α-smooth muscle actin, matrix metalloprotein-2, its tissue inhibitor and apoptotic markers: Bax and Bcl2, brain glial fibrillary acidic protein, synaptophysin, and dopaminergic receptors.

Neuroprotective effect of Valeriana wallichii rhizome extract against the neurotoxin MPTP in C57BL/6 mice

Oxidative stress and inflammation are some of the contributing factors for dopaminergic neurodegeneration in Parkinson's disease (PD). Though Valeriana wallichii D.C. is known for its nervine activities its effect against PD is yet to be studied. This is the first report on the antioxidant and anti-inflammatory effect of V. wallichii rhizome extract (VWE) in MPTP induced PD mice. GC–MS analysis of VWE indicated the presence of phytoconstituents like isovaleric acid and acacetin. PD induced mice were treated orally with three different doses (50, 100 and 200mg/kg body weight (BW)) of VWE for 14 days and their behavioural changes were studied on days 0, 8, 13 and 21. The levels of striatal dopamine, mid brain tyrosine hydroxylase positive (TH+) cell count, TH protein expression, reactive oxygen species (ROS), lipid peroxidation (LPO), antioxidants and inflammatory cytokines were analysed. Mid brain glial fibrillary acidic protein (GFAP) expression was assessed by immunohistochemistry and western blotting. Also mid brain histopathological analysis was performed. VWE treatment significantly recuperated the altered behavioural test scores, striatal dopamine levels, mid brain TH+ cell count and TH protein levels, increased GFAP expression and the histopathological changes observed in PD mice. Similarly, diminished levels of antioxidants, elevated levels of ROS, LPO and inflammatory cytokines were also significantly ameliorated following VWE treatment. The effective dose of VWE was found to be 200mg/kg BW. Conclusively, V. wallichii rhizome extract has the potential to mitigate oxidative stress and inflammatory damage in PD.

Health assessment of gasoline and fuel oxygenate vapors: Reproductive toxicity assessment

Vapor condensates of baseline gasoline (BGVC), or gasoline-blended with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for reproductive toxicity in rats at target concentrations of 2000, 10,000, or 20,000mg/m3, 6h/day, 7days/week. BGVC and G/MTBE were assessed over two generations, the others for one generation. BGVC and G/MTBE F1 offspring were evaluated for neuropathology and changes in regional brain glial fibrillary acidic protein content. No neurotoxicity was observed. Male kidney weight was increased consistent with light hydrocarbon nephropathy. In adult rats, decreased body weight gain and increased liver weight were seen. Spleen weight decreased in adults and pups exposed to G/TBA. No pathological changes to reproductive organs occurred in any study. Decreased food consumption was seen in G/TAME lactating females. Transient decreases in G/TAME offspring weights were observed during lactation. Except for a minor increase in time to mating in G/TBA which did not affect other reproductive parameters, there were no adverse reproductive findings. The NOAEL for reproductive and offspring parameters was 20,000mg/m3 for all vapor condensates except for lower offspring NOAELs of 10,000mg/m3 for G/TBA and 2000mg/m3 for G/TAME.

GFAP expression and social deficits in transgenic mice overexpressing human sAPPα

Autistic individuals display impaired social interactions and language, and restricted, stereotyped behaviors. Elevated levels of secreted amyloid precursor protein-alpha (sAPPα), the product of α-secretase cleavage of APP, are found in the plasma of some individuals with autism. The sAPPα protein is neurotrophic and neuroprotective and recently showed a correlation to glial differentiation in human neural stem cells (NSCs) via the IL-6 pathway. Considering evidence of gliosis in postmortem autistic brains, we hypothesized that subsets of patients with autism would exhibit elevations in CNS sAPPα and mice generated to mimic this observation would display markers suggestive of gliosis and autism-like behavior. Elevations in sAPPα levels were observed in brains of autistic patients compared to controls. Transgenic mice engineered to overexpress human sAPPα (TgsAPPα mice) displayed hypoactivity, impaired sociability, increased brain glial fibrillary acidic protein (GFAP) expression, and altered Notch1 and IL-6 levels. NSCs isolated from TgsAPPα mice, and those derived from wild-type mice treated with sAPPα, displayed suppressed β-tubulin III and elevated GFAP expression. These results suggest that elevations in brain sAPPα levels are observed in subsets of individuals with autism and TgsAPPα mice display signs suggestive of gliosis and behavioral impairment.

GFAP Expression as an Indicator of Disease Severity in Mouse Models of Alexander Disease

AxD (Alexander disease) is a rare disorder caused by heterozygous mutations in GFAP (glial fibrillary acidic protein) resulting in accumulation of the GFAP protein and elevation of Gfap mRNA. To test whether GFAP itself can serve as a biomarker of disease status or progression, we investigated two independent measures of GFAP expression in AxD mouse models, one using a genetic reporter of promoter activity and the other quantifying GFAP protein directly in a manner that could also be employed in human studies. Using a transgenic reporter line that expresses firefly luciferase under the control of the murine Gfap promoter (Gfap-luc), we found that luciferase activity reflected the regional CNS (central nervous system) variability of Gfap mRNA in Gfap+/+ mice, and increased in mice containing a point mutation in Gfap that mimics a common human mutation in AxD (R239H in the human sequence, and R236H in the murine sequence). In a second set of studies, we quantified GFAP protein in CSF (cerebrospinal fluid) taken from three different AxD mouse models and littermate controls. GFAP levels in CSF were increased in all three AxD models, in a manner corresponding to the concentrations of GFAP in brain. These studies demonstrate that transactivation of the Gfap promoter is an early and sustained indicator of the disease process in the mouse. Furthermore, GFAP in CSF serves as a potential biomarker that is comparable between mouse models and human patients.

IL-6 is Upregulated in Late-Stage Disease in Monkeys Experimentally Infected withTrypanosoma brucei rhodesiense

The management of human African trypanosomiasis (HAT) is constrained by lack of simple-to-use diagnostic, staging, and treatment tools. The search for novel biomarkers is, therefore, essential in the fight against HAT. The current study aimed at investigating the potential of IL-6 as an adjunct parameter for HAT stage determination in vervet monkey model. Four adult vervet monkeys (Chlorocebus aethiops) were experimentally infected with Trypanosoma brucei rhodesiense and treated subcuratively at 28 days after infection (dpi) to induce late stage disease. Three noninfected monkeys formed the control group. Cerebrospinal fluid (CSF) and blood samples were obtained at weekly intervals and assessed for various biological parameters. A typical HAT-like infection was observed. The late stage was characterized by significant (P < 0.05) elevation of CSF IL-6, white blood cell count, and total protein starting 35 dpi with peak levels of these parameters coinciding with relapse parasitaemia. Brain immunohistochemical staining revealed an increase in brain glial fibrillary acidic protein expression indicative of reactive astrogliosis in infected animals which were euthanized in late-stage disease. The elevation of IL-6 in CSF which accompanied other HAT biomarkers indicates onset of parasite neuroinvasion and show potential for use as an adjunct late-stage disease biomarker in the Rhodesian sleeping sickness.

Nasal Toxicity of Manganese Sulfate and Manganese Phosphate in Young Male Rats Following Subchronic (13-Week) Inhalation Exposure

Growing evidence suggests that nasal deposition and transport along the olfactory nerve represents a route by which inhaled manganese and certain other metals are delivered to the rodent brain. The toxicological significance of olfactory transport of manganese remains poorly defined. In rats, repeated intranasal instillation of manganese chloride results in injury to the olfactory epithelium and neurotoxicity as evidenced by increased glial fibrillary acidic protein (GFAP) concentrations in olfactory bulb astrocytes. The purpose of the present study was to further characterize the nasal toxicity of manganese sulfate (MnSO4) and manganese phosphate (as hureaulite) in young adult male rats following subchronic (90-day) exposure to air, MnSO4 (0.01, 0.1, and 0.5 mg Mn/m3), or hureaulite (0.1 mg Mn/m3). Nasal pathology, brain GFAP levels, and brain manganese concentrations were assessed immediately following the end of the 90-day exposure and 45 days thereafter. Elevated end-of-exposure olfactory bulb, striatum, and cerebellum manganese concentrations were observed following MnSO4 exposure to ≥0.01, ≥0.1, and 0.5 mg Mn/m3, respectively. Exposure to MnSO4 or hureaulite did not affect olfactory bulb, cerebellar, or striatal GFAP concentrations. Exposure to MnSO4 (0.5 mg Mn/m3) was also associated with reversible inflammation within the nasal respiratory epithelium, while the olfactory epithelium was unaffected by manganese inhalation. These results confirm that high-dose manganese inhalation can result in nasal toxicity (irritation) and increased delivery of manganese to the brain; however, we could not confirm that manganese inhalation would result in altered brain GFAP concentrations.

Sodium thiosulfate protects against acrylonitrile-induced elevation of glial fibrillary acidic protein levels by replenishing glutathione

Acrylonitrile (ACN) like many organic solvents produce neurotoxicity by elevating brain glial fibrillary acidic protein (GFAP), a putative biomarker of astrogliosis. In this study we tested the hypothesis that sodium thiosulfate (STS) protective action against ACN-induced astrogliosis is glutathione (GSH) mediated. Male Sprague–Dawley rats were administered for 2 weeks intraperitoneal doses (50 mg/kg body weight) of the ACN, with or without STS as outline in the Methods section. Specific brain regions were tested for GFAP, GSH and glutathione- S-transferase (GST) enzyme activity. In the brain regions tested STS significantly ( P≤0.05) maintained GFAP levels at the basal saline control levels, when compared to ACN-treated groups. STS also significantly ( P≤0.05) increased GSH levels in these brain regions with a corresponding increased in GST enzyme activity. Although the data indicated that STS antidotal action against ACN-induced neurotoxicity is likely to involve GSH and GST activity, other complex series of mechanisms may be involved.

Effect of Chelation withmeso-Dimercaptosuccinic Acid (DMSA) before and after the Appearance of Lead-Induced Neurotoxicity in the Rat

This paper examines whether a chelating agent (DMSA) can prevent and reverse the effects of lead (Pb) as evidenced by changes in brain glial fibrillary acidic protein (GFAP) concentration and in the habituation pattern of rearing behavior. Male F344 rats (42 days old) received Pb acetate at 150 or 2000 ppm as Pb in their drinking water for 21 days and returned to regular water for another 21 days to observe recovery. Blood Pb (BPb) concentration rose to 37 and 82 μg/dl for 150 and 2000 ppm, respectively. Rats exposed to 150 ppm Pb exhibited changes in GFAP concentration and behavioral hyperactivity, when placed in an unfamiliar cage. The 2000 ppm Pb exposure caused greater changes in GFAP, but behavioral hyperactivity appeared only postexposure, when BPb was declining. Chelation (DMSA, 50 mg/kg po, 3 times/week for 21 days) decreased the BPb concentration, and prevented and reversed the Pb-induced changes in GFAP and rearing, but not in body weight. Administration of DMSA by itself for 21 days caused no untoward effects in brain GFAP, behavior, or body weight. Concurrent administration of DMSA and Pb resulted in no evidence of additive toxicity. Results indicate that: (1) A brief behavioral test of habituation is a sensitive index of neurotoxicity and chelating therapy; (2) Pb-induced hyperactivity depends upon BPb concentration regardless of whether activity is measured during or after exposure; (3) repeated treatment with DMSA is effective in reducing Pb neurotoxicity; (4) there was no evidence that DMSA enhanced the absorption of Pb. The finding that DMSA administered late in exposure can hasten the recovery of toxic signs suggests that extracellular Pb continues to play a significant role even after toxic signs have appeared.

Sequelae of parenteral domoic acid administration in rats: comparison of effects on different metabolic markers in brain

Parenterally administered domoic acid, a structural analog of the excitatory amino acids glutamic acid and kainic acid, has specific effects on brain histology in rats, as measured usung different anatomic markers. Domoic acid-induced convulsions affects limbic structures such as hippocampus and entorhinal cortex, and different anatomic markers can detect these neurotoxic effects to varying degrees. Here we report effects of domoic acid administration on quantitative indicators of brain metabolism and gliosis. Domoic acid, 2.25 mg/kg i.p., caused stereotyped behavior and convulsions in approximately 60% of rats which received it. Six to eight days after domoic acid or vehicle administration, the animals were processed to measure regional brain incorporation of the long-chain fatty acids [1- 14C]arachidonic acid ([ 14C]AA) and [9,10- 3H]palmitic acid ([ 3H]PA), or regional cerebral glucose utilization ( rCMR glc) using 2-[1- 14C]deoxy- d-glucose, by quantitative autoradiography. Others rats were processed to measure brain glial fibrillary acidic protein (GFAP) by enzyme-linked immunosorbent assay. Domoic acid increased GFAP in the anterior portion of cerebral cortex, the caudate putamen and thalamus compared with vehicle. However, in rats that convulsed after domoic acid GFAP was significantly increased throughout the cerebral cortex, as well as in the hippocampus, septum, caudate putamen, and thalamus. Domoic acid, in the absence of convulsions, decreased relative [ 14C]AA incorporation in the claustrum and pyramidal cell layer of the hippocampus compared with vehicle-injected controls. In the presence of convulsions, relative [ 14C]AA incorporation was decreased in hippocampus regions CA1 and CA2. Uptake of [ 3H]PA into brain was unaffected. Relative rCMR glc decreased in entorhinal cortex following domoic acid administration with or without convulsions. These results suggest that acute domoic acid exposure affects discrete brain circuits by inducing convulsions, and that domoic acid-induced convulsions cause chronic effects on brain function that are reflected in altered fatty acid metabolism and gliosis. © 1977 Elsevier Science B.V. All rights reserved.

Detection of the peripheral nervous system (PNS)-type glial fibrillary acidic protein (GFAP) and its mRNA in human lymphocytes

Glial fibrillary acidic protein (GFAP), an astroglial marker, has been detected in the peripheral nervous system (PNS) in a shorter version and its mRNA in a longer form (beta-type) than the brain alpha-type. To determine the characteristics of the GFAP gene expression in nonneural cells, we have investigated its in vivo transcription and translation products in human lymphocytes. Using RT-PCR, we demonstrate that the GFAP gene is transcribed in these cells. Most or all of the mRNA resulting from this transcription was longer than the brain-type at its 5' end and thus may correspond to the beta-type. In addition, immunoblotting of lymphocyte extracts with a monoclonal antibody revealed a 41 KDa fragment instead of the 50 KDa expected from brain GFAP. These results suggest that GFAP expression in lymphocytes is preferentially of the PNS beta-type giving rise to longer mRNA and shorter protein. However, compared to two other astroglial mRNAs (S-100beta and aldolase C) which were synthesized in significant amounts in lymphocytes, GFAP mRNA was detected in minute amounts representing 0.03% of the brain level. This low expression may subserve a special role in lymphocytes since it is translated.

Persistent Alterations in Regional Brain Glial Fibrillary Acidic Protein and Synaptophysin Levels Following Pre- and Postnatal Polychlorinated Biphenyl Exposure

Pregnant Wistar WU rats were exposed to 0, 5, and 25 mg of the commercial polychlorinated biphenyl (PCB) mixture Aroclor 1254 per kilogram of body weight on Days 10 to 16 of gestation. Pregnant rats were sacrificed on Gestation Day 20 to observe effects on fetal body and brain weights. Male and female offspring were sacrificed on Postnatal Days 21 and 90 (PND21 and PND90, respectively) and examined for treatment-related effects on neurochemical parameters. The concentrations of the neuronal and glial cell markers, synaptophysin and glial fibrillary acidic protein (GFAP), were measured in diverse brain regions from the offspring using immunochemical techniques. The level of calcineurin (a calmodulin-regulated protein phosphatase) activity was measured in cerebellar homogenates. In addition, ethoxyresorufinO-deethylase (EROD) activity was determined in hepatic microsomes as a measure of a well-characterized response to PCB exposure in experimental animals. The major alterations of GFAP levels following maternal PCB treatment were significant increases in the lateral olfactory tract (LOT) and the cerebellum (CB) and significant decreases in the brain stem (BS) of the offspring on PND21 and 90. Synaptophysin levels were significantly decreased relative to controls in the LOT, prefrontal cortex, and striatum of the offspring on PND90. In the BS, synaptophysin levels were significantly decreased relative to controls in male and female weanlings on PND21 and males on PND90; however, significant increases were observed in the BS of females on PND90. No effect of maternal PCB treatment was observed on levels of GFAP and synaptophysin in the dorsal hippocampus on PND21 and 90. Due to analytical restrictions statistical comparisons of GFAP levels were limited to examining the effect of maternal PCB treatment per brain region per sex per time point. Calcineurin activity was decreased in the female CB on PND21, but a significant increase in activity was observed in the female CB on PND90. No effect of maternal PCB treatment was observed on the cerebellar calcineurin activity in male offspring on PND21 and 90. EROD activity was highly induced in maternal microsomes from both PCB treatment groups, but only slightly induced in fetal hepatic microsomes. On PND21 weanling hepatic microsomal EROD activity was highly induced following gestational and lactational PCB exposure; however, on PND90 EROD activity was unaffected by maternal PCB treatment in male offspring and significantly decreased in female offspring. The results of the present study indicate that gestational and lactational exposure to the commercial PCB mixture results in long-term alterations in a neuronal and glial cell markers in specific brain regions of rats. These marker proteins may be useful for determining the strucure–activity relationships in PCB-induced developmental neurotoxicity.

Reexpression of glial fibrillary acidic protein rescues the ability of astrocytoma cells to form processes in response to neurons.

Astroglial cells play an important role in orchestrating the migration and positioning of neurons during central nervous system development. Primary astroglia, as well as astrocytoma cells will extend long stable processes when co-cultured with granule neurons. In order to determine the function of the glial fibrillary acidic protein (GFAP), the major intermediate filament protein in astroglia and astrocytoma cells, we suppressed the expression of GFAP by stable transfection of an anti-sense GFAP construct in human astrocytoma U251MG cells. The resulting AS2-U251 cells can no longer extend stable processes in the presence of granule neurons. To show that this effect is due specifically to the absence of GFAP, we reintroduced a fully encoding rat brain GFAP cDNA into these AS2-U251 cells. The resulting rat GFAP appeared as a filamentous network and the reexpression of GFAP rescued the ability of these astrocytoma cells to form stable processes when co-cultured with neurons. From these results, it is clear that the glial specific intermediate filament protein, GFAP, is required for process extension of these astrocytoma cells in response to granule neurons.