Distribution of glial fibrillary acidic protein in central nervous system lesions of tuberous sclerosis

The distribution of glial fibrillary acidic protein (GFAP) in the central nervous system (CNS) lesions of tuberous sclerosis (TS) was examined using antiserum against GFAP and the peroxidase antiperoxidase method of Sternberger. In cortical tubers there were islands of gemistocytic astrocytes staining intensely for GFAP and occasional giant cells having some cytoplasmic staining. The majority of the cortical giant cells had no GFAP. The islands were separated by areas devoid of astrocytes with perikaryal staining. A faintly staining fibrous network was found between these islands. The majority of cells in the subependymal nodules stained. The retinal phakoma stained but not as intensely as the subependymal nodules. There was no staining whatsoever in the giant cell subependymal tumors. Absence of GFAP staining in the subependymal giant cell tumors makes their classification as astrocytomas less certain.     

Suppression of glial tumor growth by expression of glial fibrillary acidic protein

We examined the effect of expression of glial fibrillary acidic protein (GFAP) on the tumor growth of astrocytoma in vivo. When rat astrocytoma C6 cells were injected subcutaneously in athymic mice, the cells produced tumors that grew rapidly. The tumor growth of C6 cells transfected with GFAP cDNA was significantly reduced compared to that of control NeoC6 cells transfected only with the neomycin resistant gene. After implantation of C6 cells transfected with mutated GFAP cDNA at the phosphorylation sites, the tumor growth was suppressed similar to that of the wild GFAP transfectants. To determine whether the cell growth suppression by GFAP is specific for astroglial cells, we assessed the effect of GFAP on the cell growth of an L cell of fibroblast origin in vitro. By GFAP cDNA transfection, L cells showed morphological changes, but the cell growth was not reduced. These results suggest that GFAP is a critical regulator of the tumor growth of astrocytoma.     

Glial cells in the enteric nervous system contain glial fibrillary acidic protein

The complex nervous networks found throughout the mammalian gut--the enteric nervous system--are histologically, ultrastructurally, and, to some extent, functionally--similar to the central nervous system. The glial cells of the small enteric ganglia are generally classified as Schwann or satellite cells, since they are found in the peripheral nervous system, possess nuclei which ultrastructurally resemble those of Schwann cells and are derived from the neural crest. However, it has been argued that these cells resemble astrocytes of the central nervous system with respect to gross and fine structure, and their relationship with the enteric neurones and their processes. In immunohistochemical studies of these cells, both in frozen sections of gut wall and in tissue culture preparations of the enteric plexuses, we found evidence that the enteric glial cells are rich in glial fibrillary acidic protein (GFAP), a protein associated with the 100 A glial intermediate filaments, and hitherto believed to be specific to astrocytes of the central nervous system only.     

Axonal and nonneuronal cell responses to spinal cord injury in mice lacking glial fibrillary acidic protein

We have examined the regeneration of corticospinal tract fibers and expression of various extracellular matrix (ECM) molecules and intermediate filaments [vimentin and glial fibrillary acidic protein (GFAP)] after dorsal hemisection of the spinal cord of adult GFAP-null and wild-type littermate control mice. The expression of these molecules was also examined in the uninjured spinal cord. There was no increase in axon sprouting or long distance regeneration in GFAP-/- mice compared to the wild type. In the uninjured spinal cord (i) GFAP was expressed in the wild type but not the mutant mice, while vimentin was expressed in astrocytes in the white matter of both types of mice; (ii) laminin and fibronectin immunoreactivity was localized to blood vessels and meninges; (iii) tenascin and chondroitin sulfate proteoglycan (CSPG) labeling was detected in astrocytes and the nodes of Ranvier in the white matter; and (iv) in addition, CSPG labeling which was generally less intense in the gray matter of mutant mice. Ten days after hemisection there was a large increase in vimentin+ cells at the lesion site in both groups of mice. These include astrocytes as well as meningeal cells that migrate into the wound. The center of these lesions was filled by laminin+/fibronectin+ cells. Discrete strands of tenascin-like immunoreactivity were seen in the core of the lesion and lining its walls. Marked increases in CSPG labeling was observed in the CNS parenchyma on either side of the lesion. These results indicate that the absence of GFAP in reactive astrocytes does not alter axonal sprouting or regeneration. In addition, except for CSPG, the expression of various ECM molecules appears unaltered in GFAP-/- mice.     

Decreases in brain glial fibrillary acidic protein (GFAP) are associated with increased serum corticosterone following inhalation exposure to toluene

Toluene and other neurotoxicants can cause both increases and decreases in the concentration of GFAP in the brain. While increased GFAP concentration is widely regarded as evidence for reactive gliosis, toxicant-induced decreases in GFAP have received less attention. In order to identify conditions under which inhalation exposure to toluene results in decreased GFAP concentration, rats were subjected to repeated inhalation of toluene for up to 7 days. Adult male F344 rats received inhalation exposure to air or to 1000 ppm toluene, 6 hr/day, for 3 or 7 days. This toluene exposure replicated the previously-observed decreases in GFAP in the thalamus. Serum Corticosterone was significantly elevated in the same rats that exhibited decreases in brain GFAP concentration. These results show that decreases in brain GFAP might be a consequence of disruption of the hypothalamic-pituitary-adrenal axis and/or hormonal homeostasis. Changes in GFAP and in Cort were not accompanied by a change in body weight. More research is needed to firmly establish cause and effect between increased serum glucocorticoid levels and GFAP decreases following toluene inhalation and to determine whether these decreases indicate toxicity or adaptive changes.     

Postnatal morphologic changes and glial fibrillary acidic protein immunoreactivity in the anteroventral cochlear nucleus of the acoustically-deprived gerbil

This study investigated the morphological changes and glial fibrillary acidic protein immunoreactivity (GFAP-IR) in the anteroventral cochlear nucleus (AVCN) of acoustically-deprived gerbils during postnatal development. The mongolian gerbil, Meriones unguiculatus, had been acoustically deprived on the right side or left side by a surgical ligation of the external auditory canal at postnatal day 12-14. No discernible microcysts were located in the ipsilateral AVCN at one, three, six and nine months after monaural ligation. Also, no discernible microcysts were located in the contralateral AVCN at one and three months after monaural ligation. Numerous microcysts were located in the contralateral AVCN at six months after monaural ligation and were slightly reduced in number at nine months after monaural ligation. Some of the microcysts closely apposed to and connected with the blood vessels through a leakage route or channel. A foamy region was found in the superficial granule cell cap of the AVCN. The foamy region became evident in the ipsilateral AVCN at three months after monaural ligation. However, the foamy region became evident in the contralateral AVCN at three and nine months after monaural ligation. Vacuoles were mainly found in the neuronal cells at the junction of the superficial and deep layers in the AVCN. These vacuoles were found in the contralateral AVCN at one, three, six, and nine months after monaural ligation. However, vacuoles were found in the ipsilateral AVCN only at three months after monaural ligation. Morphological changes of the myelin sheath were found to be more severe in the contralateral AVCN than in the ipsilateral. GFAP-IR was located in the superficial layer of the contralateral AVCN at three and nine months after monaural ligation. However, GFAP-IR was found in the superficial and deep layers of the ipsilateral AVCN at three and nine months after monaural ligation. GFAP-IR was also found in the superficial layers of the ipsilateral AVCN at six months after monoaural ligation. Microcysts are presumably derived from the detachment of the myelin sheath from the retracted axons, protrusion of the myelin sheath, and disruption of the myelin sheath. The major conclusions were that (1) microcysts were greatly reduced following acoustical ligation during postnatal development, and (2) blood vessels and GFAP-immunoreactive astrocytes may be involved in the depletion of microcysts for maintaining the homeostasis of the microenvironment in the cochlear nuclei.     

Analysis of c-Fos and glial fibrillary acidic protein (GFAP) expression following topical application of potassium chloride (KCl) to the brain surface

The mustached bat, Pteronotus p. parnellii, has a finely tuned cochlea that rings at its resonant frequency in response to an acoustic tone pip. The decay time (DT) and frequency of these damped oscillations can be measured from the cochlear microphonic potential (CM) to study changes in cochlear mechanics. In this report, we describe phasic changes that occur in synchrony with communication sound vocalizations of the bat. Three animals with chronically implanted electrodes were studied. During the experiments, 1-2 ms tone pips were emitted from a speaker every 200 ms. This triggered a computer analysis of the resulting CM to determine the DT and cochlear resonance frequency (CRF) of the ringing. The time relative to vocalizations was determined by monitoring the output of a microphone placed near a bat's mouth. Similar results were obtained from all three bats tested. In a representative case, the average DT was 2.33 +/- 0.25 ms while the bat was quiet, but it decreased by 46% to 1.26 +/- 0.75 during vocalizations, which indicates a greater damping of the cochlear partition. Sometimes, DT started decreasing immediately before the bat vocalized. After the end of a vocalization, the return to baseline values varied from rapid (milliseconds) to gradual (1-2 seconds). The CRF also changed from baseline values during vocalization, although the amount and direction of change were not predictable. When gentamicin was administered to block the action of medial olivocochlear (MOC) efferents, DT reduction was still evident during vocalization but less pronounced. We conclude that phasic changes in damping occur in synchrony with vocalization, and that the MOC system plays a role in causing suppression. Since suppression can begin prior to vocalization, this may be a synkinetic effect, mediated by neural outflow to the ear in synchrony with neural outflow to the middle ear muscles and the muscles used for vocalization.     

Glial fibrillary acidic protein expression but no glial demarcation follows the lesion in the molecular layer of cerebellum

The present study investigates the reactive gliosis following a simple stab wound lesion to a brain area in which a characteristic astroglial architecture exists, i.e., the Bergmann-glia in the molecular layer of cerebellum. While in mammalian brain the Bergmann-glia contains glial fibrillary acidic protein (GFAP), in the avian Bergmann-glia, the cytoskeletal protein is vimentin, which is characteristic for immature astroglia in mammals. The operations were performed on chickens and rats under deep anaesthesia, using a sterile disposable needle. After a 1-week survival period, the animals were overdosed with ether and perfused transcardially with 4% buffered paraformaldehyde. Free-floating sections cut with a vibration microtome were processed for immunohistochemistry against GFAP and vimentin. GFAP immunopositivity of Bergmann-glia appeared in chicken and increased in rat in the lesioned area but the lesion was not surrounded by typical astrocytes and no demarcation was formed in the molecular layer, in contrast to the usual appearance of reactive gliosis, which was observed in the granular layer and in the white matter in both species. Vimentin immunopositivity of the Bergmann-glia also increased around the lesion in both species. The results suggest that a highly developed glial architecture fails to re-arrange into a demarcating scar, which offers an interesting model system to study the importance of glial demarcation. The observations also support that the resident glia is the main component of the glial reaction, and prove the capability of avian Bergmann-glia to express GFAP.     

Astroglial architecture of the carp (Cyprinus carpio) brain as revealed by immunohistochemical staining against glial fibrillary acidic protein (GFAP)

The present paper is the first comprehensive study on the astroglia of a teleost fish that is based on the immunohistochemical staining of GFAP (glial fibrillary acidic protein, an immunohistochemical marker of astroglia). The ray-finned fishes (Actinopterygii) and their largest group, the Teleostei, represent a separate pathway of vertebrate evolution. Their brain has a very complex macroscopic structure; several parts either have no equivalents in tetrapods or have a very different shape, e.g., the telencephalon. The results show that the teleost brain has a varied and highly specialized astroglial architecture. The primary system is made up of radial glia, which are of ependymal origin and cover the pial surface with endfeet. The tendency is, however, that the more caudal a brain area is, the less regular is the radial arrangement. A typical radial glia dominates some parts of the diencephalon (median eminence, lobus inferior and habenula) and the telencephalon. In the rest of the diencephalon and in the mesencephalon, the course of the glial fibers is modified by brain tracts. The most specialized areas of the teleost brain, the optic tectum and the cerebellum, display elaborate variations of the original radial system, which is adapted to their layered organization. In the cerebellum, an equivalent of the Bergmannglia can be found, although its fiber arrangement shows meaningful differences from that of mammals or birds. In the lower brain stem radial glia are confined to fibers separating the brain tracts and forming the midline raphe. A dense ependymoglial plexus covers the inner surface of the tectum and the bottom of the rhombencephalic ventricle, intruding into the vagal and facial lobes. The structure and the position of the rhombencephalic plexus suggest that it corresponds to a circumventricular organ that entirely occupies the bottom of the ventricle. Perivascular glia show an unusual form as they consist of long fibers running along the blood vessels. In the large brain tracts long glial fibers run parallel with the course of the neural fibers. At least in the diencephalon, these glial fibers seem to be modified radial fibers. Real astrocytes (i.e., stellate-shaped cells) can be found only in the brain stem and even there only rarely. The glial specialization in the various areas of the teleost brain seems to be more elaborate than that found either in amphibia or in reptiles.     

Thyroid hormone induces protein secretion and morphological changes in astroglial cells with an increase in expression of glial fibrillary acidic protein

Degradation and utilization of protein by Prevotella ruminicola B1(4), a proteolytic bacterium that is prominent in the rumen, was examined. In preliminary experiments, proteinaceous N sources produced faster growth rates than did NH4Cl, based on changes in optical density over time. However, ammonium chloride produced a greater maximum cell density than did proteinaceous N sources. Of the proteinaceous N sources, an enzymatic hydrolysate of soybean protein with a relative peptide size of 3 AA residues produced a greater growth rate and maximum cell density compared with the other proteinaceous N sources. Further experiments revealed that P. ruminicola B1(4) grew faster and to a greater final dry weight with soybean protein than with casein. Degradation of both proteins was low as was indicated by the slow disappearance of soluble protein, low concentrations of free AA and peptides, and the decrease in ammonia concentrations over time. Patterns of degradation did differ between the two proteins, however. Accumulation of peptides and free AA from soybean protein peaked 2 h earlier than those from casein, and concentrations of free AA and peptides from soybean protein were lower on average than those from casein. Prevotella ruminicola B1(4) preferentially utilized Asp, Ile, Leu, Lys, and Arg from soybean protein compared with casein. The relative size of peptides that accumulated from both proteins, as determined by the ratio of ninhydrin reaction after HCl hydrolysis to ninhydrin reaction before HCl hydrolysis, suggested that part of the proteolytic activity of P. ruminicola B1(4) is a dipeptidase. Our findings suggest that P. ruminicola may have a greater impact on peptide degradation than on protein degradation in the rumen.     

Astrogliosis in culture: I. The model and the effect of antisense oligonucleotides on glial fibrillary acidic protein synthesis

Astrogliosis is a predictable response of astrocytes to various types of injury caused by physical, chemical, and pathological trauma. It is characterized by hyperplasia, hypertrophy, and an increase in immunodetectable glial fibrillary acidic protein (GFAP). As GFAP accumulation is one of the prominent features of astrogliosis, inhibition or delay in GFAP synthesis in damaged and reactive astrocytes might affect astrogliosis and delay scar formation. The aim of this study is to investigate the possibility of utilizing antisense oligonucleotides in controlling the response of astrocytes after mechanically induced injury. We scratched primary astrocyte cultures prepared from newborn rat cerebral cortex with a plastic pipette tip as an injury model and studied the astrogliotic responses in culture. Injured astrocytes became hyperplastic, hypertrophic, and had an increased GFAP content. These observations demonstrate that injured astrocytes in culture are capable of becoming reactive and exhibit gliotic behaviors in culture without neurons. The increase in GFAP content in injured astrocytes could be inhibited by incubating the scratched culture with commercially available liposome complexed with 3' or 5' antisense oligonucleotides (20 nt) in the coding region of mouse GFAP. The scratch model provides a simple system to examine in more detail the mechanisms involved in triggering glial reactivity and many of the cellular dynamics associated with scar formation. Antisense oligonucleotide treatment could inhibit the GFAP synthesis in injured astrocytes, hence it may be applicable in modifying scar formation in CNS injury in vivo.     

Nerve gas-induced seizures: role of acetylcholine in the rapid induction of Fos and glial fibrillary acidic protein in piriform cortex

Soman (pinacolymethylphosphonofluoridate), a highly potent irreversible inhibitor of acetylcholinesterase (AChE), causes seizures and rapidly increases Fos and glial fibrillary acidic protein (GFAP) staining in piriform cortex (PC). This suggests that the inhibition of AChE by soman leads to increased acetylcholine (ACh) and neuronal excitability in PC. The sole source of cholinergic input to PC is from the nucleus of the diagonal band (NDB). To investigate the role of ACh in soman-induced seizures, we lesioned cholinergic neurons in NDB unilaterally with 192-IgG-saporin. By 10 d, saporin eliminated staining for choline acetyltransferase (ChAT), the synthetic enzyme for ACh, in NDB ipsilateral to the lesion. Staining for AChE, the degradative enzyme for ACh, was eliminated in PC ipsilateral to the lesioned NDB. By 45-60 min after soman, increased Fos and GFAP staining in PC was evident only ipsilateral to the unlesioned NDB. By 90-120 min after soman, Fos and GFAP staining increased bilaterally in PC. In a second experiment, electrical stimulation electrodes were implanted unilaterally in the NDB to activate focally the projections to PC in unanesthetized rats. Within 5 min of NDB stimulation, there were clear behavioral and EEG signs of convulsions. After 45-60 min of NDB stimulation, there was increased Fos and GFAP staining in layer II of PC ipsilateral to the stimulation site. Pretreatment with the selective muscarinic receptor antagonist scopolamine blocked the convulsions and prevented increased Fos and GFAP staining in PC. These results suggest that ACh release in PC triggers the initiation of seizures and gliosis after soman administration, predominantly by the activation of muscarinic receptors.     

Down-regulation of glial fibrillary acidic protein expression during acute lytic varicella-zoster virus infection of cultured human astrocytes

The effects of the varicella-zoster virus (VZV) OKA vaccine strain in producing morphologic and antigenic changes in dissociated cultures of human fetal brain was investigated. Cultures containing 80% glial acidic fibrillary protein (GFAP), GFAP+ (positive) astrocytes and 20% GFAP- (negative) fibroblastic-like cells were infected with cell-free VZV OKA at a multiplicity of infection of 0.1 plaque-forming units per cell. Cytopathic effects and significant viral antigen labeling with antibodies against VZV gpl and immediate-early (IE) protein 62 were first detected 6 to 7 days postinfection. Several observations indicated that astrocyte GFAP expression was altered and diminished as a result of VZV infection itself, thereby raising doubts about the utility of combining cell markers and viral antigenic labeling in assessing the susceptibility of neural cell types to viral infection. The down-regulation of GFAP expression by VZV appears to be mediated by early rather than late events in the viral replication cycle and may not be the result of virally induced global shut-off of host cell protein synthesis. Similar observations were made using VZV Ellen, a multipassaged, nonvaccine strain. These observations have potential in vivo implications related to histologic analysis of VZV-infected tissues and disease pathogenesis.     

Unusual fibro-osseous lesion of the spinal cord with positive staining for glial fibrillary acidic protein and radiological progression: a case report

A rare intradural lesion of the lumbar spine producing leg pain and minimal neurological deficits is described in a 48-year-old man. Previous reports of similar lesions have been described under the designation "fibro-osseous lesions" and "calcifying pseudoneoplasms." This is the first report of an unusual fibro-osseous lesion with an intradural spinal location as well as the first to show immunohistochemical positivity for glial fibrillary acidic protein (GFAP) within cellular components of this process and crystal formation suggestive of calcium pyrophosphate. This case also shows radiographic progression suggesting the possibility that this entity may be a form of low grade neoplasm.     

Glial fibrillary acidic protein in CSF of multiple sclerosis patients: relation to neurological deficit

Glial fibrillary acidic protein (GFAp) was analysed in cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) and healthy controls. Patients with relapsing-remitting course (n = 13) were followed with quantitative neurological examinations and lumbar punctures during a 24-month period. The patient group was a subsample from a randomised, double-blind clinical trial of acyclovir on MS: 7 patients were treated with acyclovir and 6 were placebo controls. CSF was also collected from 5 age-matched healthy individuals with normal quantitative neurological examinations. The CSF assays disclosed increased concentrations of GFAp in MS patients compared to controls (p < 0.01). Furthermore, the GFAp levels correlated significantly with the deficit score (p < 0.01) but not with exacerbation frequency. When the group treated with acyclovir was compared with the placebo group, no significant change of CSF GFAp was observed. In the present study we show that GFAp is increased in CSF of patients with MS and that the levels correlate with the neurological dysfunction. Further work is needed to ascertain whether determinations of CSF GFAp can be used to monitor disease progression in MS or whether the assay may be useful to evaluate therapeutic intervention.