Biomedical subjects

F Hajós

Publications and source records attributed to F Hajós.

At least 37 records · Page 2Linked to original sources

PubMed1995

Species-specificity of glial vimentin as revealed by immunocytochemical studies with the Vim 3B4 and V9 monoclonal antibodies.

Two monoclonal antibodies directed against vimentin, Vim 3B4 and V9 could distinguish between vimentins originating from certain species, when tested on cell lines (Bohn et al, 1992). Our comparative immunohistochemical studies in the rat and chicken brain with the same antibodies suggest the coexistence of two vimentin forms in the glial cells of both species. One of these forms bearing the epitope present in the respective non-glial cell lines is present in astrocytes and Bergmann glia independently of the ontogenic state of the animal. The other epitope appeared also mutually in both species, albeit its expression was more restricted. These patterns suggest that in these two species, the expression of the different vimentin forms might be differently regulated.

Aging↗

PubMed1994

Maturation of the GFAP-immunopositive glial network is delayed in the olfactory bulbs of rats subjected to early, low-dose X-irradiation.

Young rats were subjected to low-level, repeated doses of x-irradiation from a Co60 source and examined for the presence and arrangement of their GFAP-immunopositive system at the light and electron microscopic levels. In 2-week-old control rats, labelled cells were already distributed homogeneously throughout the bulb, while in the experimental animals, a (newborn- and early postnatal-type) radial arrangement of immunoreactive fibres continued to persist even until the end of the fourth postnatal week. This delay in the maturation of the GFAP-immunopositive glial system may contribute to the hindered development of the bulbar neurones, neuronal connections, and field potentials, as found in earlier studies.

Animals↗

PubMed1994

Structural maturation, cell proliferation and bioelectric activity in long-term slice-cultures of immature rat hippocampus.

Explants of transverse slices of the 6-day-old rat hippocampus were grown in a serum-free medium for 2-14 days. Histology performed after various culturing periods demonstrated that these slices maintain a high degree of 3-dimensional organotypy, while undergoing growth and differentiation of the main cellular elements similar to that seen in vivo. Histological indications of continuing cell proliferation were verified by autoradiography showing a labelling of neuroblasts in the dentate gyrus and of glioblasts at the sites of gliogenesis observed in vivo. Spontaneous bioelectric activity and evoked potentials were recorded, both indicating the development of impulse generation and neuronal connectivity within the explant. Silver impregnation and electron microscopic studies lent further support for the presence of neuronal networks intrinsic to the hippocampus. These findings suggest that within the period studied the hippocampal slice cultures mature in a fashion similar to that seen in situ.

Animals↗

PubMed1993

Vasoactive intestinal polypeptide immunoreactive structures in the mouse barrel field.

Immunohistochemistry for vasoactive intestinal polypeptide was carried out in tangentially cut vibratome sections of the barrel cortex in adult mice. Sections through layer IV have revealed an association between the cytoarchitectonically visible modular organization of barrels and the distribution of immunoreactive axon terminals. These terminals are preferentially localized in the side region of a barrel, whereas the hollow shows a relative scarcity of these structures as shown with image analysis. This finding is the first direct demonstration of a modular distribution of vasoactive intestinal polypeptide-containing axon terminals in the neocortex.

Animals↗

PubMed1993

Long-term effects of anterograde degeneration on astroglial reaction in the rat geniculo-cortical system as revealed by computerized image analysis.

Changes in the expression of glial fibrillary acidic protein by astrocytes in the primary visual cortex of adult albino rats were analyzed with immunohistochemistry after unilateral destruction of the dorsal lateral geniculate nucleus. An increase in number of glial fibrillary acidic protein-immunoreactive astrocytes could be detected in the visual cortex of the side ipsilateral to the lesion in the short-term survival group (7-11 days post lesion), but this increase was extremely reduced after a postlesional survival time of 150 days. The quantitation of the glial response by image analysis showed, that the initial increase was mainly localized in the cortical layers II-IV, where the geniculo-cortical input terminates. The transient nature of this process was revealed by the measurements in the long-term survival group, where differences between experimental and control sides were substantially reduced. We conclude, that the remote glial response in the visual cortex is transient and that is disappearance indicates the end of a postlesional adaptation period in the neuropil.

Animals↗

PubMed1993

Matching localization of vasoactive intestinal polypeptide (VIP) and VIP-receptor at pre- and postsynaptic sites in the mouse visual cortex.

Vibratome sections of the mouse occipital cortex were processed by double label immunohistochemistry to demonstrate the localization of the receptor for vasoactive intestinal polypeptide and the peptide itself. The receptor was found to be distributed in the cytoplasm and major dendrites of numerous cortical cells, mainly pyramidal neurons. Vasoactive intestinal polypeptide, on the other hand, occurred in a population of non-pyramidal neurons and axonal boutons. Image analysis revealed a close spatial association of peptide-containing presynaptic terminals with receptor-containing cells. Ultrastructurally, these connections represented symmetrical axo-somatic and axo-dendritic synapses. Our findings demonstrate a matching histological localization of vasoactive intestinal polypeptide and its receptor in the brain.

Animals↗

PubMed1993

Astroglial reaction following Wallerian degeneration in the rat visual cortex: proliferation or hypertrophy?

Following chemical lesioning of the rat dorsal lateral geniculate nucleus the visual cortical astrocytes were investigated with light and electron microscopy. A quantitative evaluation of astrocyte distribution within the cortex was also carried out. Findings suggest that while the number of cortical astrocytes remains fairly constant, they become hypertrophic and shifted towards the upper layers of the visual cortex. It is concluded that the degeneration of synaptic input to the visual cortex triggers the translocation and hypertrophy rather than proliferation of astrocytes.

Animals↗

PubMed1992

Slices from the rat olfactory bulb maintained in vitro. Morphological aspects.

Transverse, 400-microns-thick slices of 8-day-old rat olfactory bulb were incubated in Krebs-Henseleit medium with and without oxygenation. Following incubation, slices were fixed in aldehyde-osmium and embedded in resin for light and electron microscopy. After 2 h of incubation oxygenated preparations showed a structural preservation comparable to that of the freshly fixed olfactory bulb. Under hypoxic conditions mitral cells located on the medial side of the bulb were the most sensitive to the interruption of gassing, while ventricular cells and glomeruli were remarkably resistant as judged by morphological standards. The effects of short-term (up to 30 min) interruptions of gassing proved to be reversible. Our findings suggest that the incubated olfactory bulb slice may be a useful preparation for functional morphological studies.

Animals↗

PubMed1991

Developmental gradients of vasoactive intestinal polypeptide (VIP)-containing neurons in the rat visual cortex detected by image analysis.

The postnatal development of vasoactive intestinal polypeptide-immunoreactive (VIP-IR) neurons was followed by computer-assisted image analysis in the rat visual cortex. The laminar distribution of all VIP-IR structures was measured. These structures were subdivided into cell somata, dendritic profiles and axonal boutons and measured separately. VIP-IR neurons were first seen on postnatal day 1, mostly in the upper half of the presumptive visual cortex. A localization of cell bodies similar to that in the adult is reached between days 12 and 16. VIP-IR dendrites have a protracted growth period as compared to perikarya, involving a developmental gradient from an even distribution to a concentration in the upper cortical layers. This is due to the formation of dendritic terminal arbors after the second postnatal week. Scattered VIP-IT axonal boutons appear on day 3 in the midportion of the presumptive visual cortex. Their typical laminar distribution in layers II, IV and lower VI was observed after day 12. Our results suggest that the biochemically detected sharp increase in VIP levels after the second postnatal week is due to the maturation of cell processes as a morphological basis of neuronal connectivity.

Aging↗

PubMed1991

Mapping of glial fibrillary acidic protein-immunoreactivity in the rat forebrain and mesencephalon by computerized image analysis.

Computer-assisted image analysis was used to map the regional distribution of glial fibrillary acidic protein-immunoreactive (GFAP-IR) astrocytes in the rat forebrain and mesencephalon. A complete survey of packing densities of GFAP-IR structures was performed. Computer maps revealed high values in the outer and inner layers of the cortex, some hippocampal and olfactory bulb layers, prepiriform cortex, dorsal part of the caudate-putamen, globus pallidus, lateral septum, reticular thalamic nucleus, lateral habenular nucleus, circumventricular organs, nuclei of the medial hypothalamus, substantia nigra, interpeduncular nucleus, and mamillary body. These correspond to regions of the embryonic pial and ventricular brain surfaces, which undergo developmental alterations including growth and various forms of internalization. From this we conclude that in the adult brain, astrocytes of high GFAP-IR are derivatives of surface-contact glia, whereas those located in areas having developed by the local thickening of the neural tube wall show reduced or no GFAP-IR.

Animals↗

PubMed1991

Enantioselectivity at the physiologically active GABAA receptor.

A subfraction of cortical tissue from rat brain, containing membrane vesicles was prepared freshly with added protease inhibitors and antioxidant. The preparation was used to measure stimulation of transmembrane 36C1- flux and inhibition of bicuculline-sensitive [3H] muscimol binding by (+)-(S) and (-)-(R) enantiomers of dihydromuscimol at 30 degrees in physiological salt solution. Displacement of bound [3H]muscimol and stimulation of 36Cl- flux appeared in the 0.1-10 microM concentration range of the enantiomers, channel gating, however, required rather high concentrations. Degrees of enantioselectivity for channel gating, desensitization of and binding to GABAA receptors were estimated by the concentration ratios of dihydromuscimol enantiomers, [(-)-(R)]/[(+)-(S)], at the same level of response or displacement. Different enantioselectives were observed for channel gating (6 +/- 3), receptor binding (3 +/- 2) and desensitization (no selectivity). The low and concentration-dependent enantioselectives found for channel gating and receptor binding can be explained by desensitization and heterogeneity of GABAA receptors.

Animals↗

PubMed1990

Alterations in glial fibrillary acidic protein immunoreactivity in the upper dorsal horn of the rat spinal cord in the course of transganglionic degenerative atrophy and regenerative proliferation.

Transection of a peripheral nerve induces marked increase in the glial fibrillary acidic protein (GFAP) immunoreactivity in the ipsilateral, segmentally related upper dorsal horn. Increase of GFAP immunoreaction is similar to, but not identical with, that observed after dorsal rhizotomy. If the peripheral nerve succeeds in regenerating, GFAP immunoreactivity in the upper dorsal horn returns to normal. It is concluded that the amount and distribution of GFAP is determined by transganglionic degenerative atrophy. Wallerian degeneration and regenerative proliferation of dorsal root axon terminals, respectively.

Animals↗

PubMed1990

Remote astrocytic response as demonstrated by glial fibrillary acidic protein immunohistochemistry in the visual cortex of dorsal lateral geniculate nucleus lesioned rats.

The reaction of astroglia was investigated after unilateral destruction of the dorsal lateral geniculate nucleus in the primary visual cortex of adult albino rats. The destruction of the dorsal lateral geniculate nucleus was performed by stereotaxic injections of ibotenic acid, and the location was verified in Nissl stained sections in each animal. Electron microscopic observations demonstrated the presence of degenerating axon terminals surrounded by hypertrophic astroglial processes mainly in layers III and IV of the ipsilateral primary visual cortex. The ipsilateral (impaired) and contralateral (control) sides of the primary visual cortex showed light microscopically a clearly differing appearance and distribution of glial fibrillary acidic protein (GFAP) immunoreactivity 7 to 11 days after the unilateral injection of ibotenic acid into the dorsal lateral geniculate nucleus. Whereas the control side of the primary visual cortex showed GFAP staining only in the subpial zone of layer I and close to the white matter, all layers of the impaired cortex showed an intense GFAP immunoreactivity. The increase in immunoreactivity was confined to the primary visual cortex. The extent of and increase in immunoreactivity was corroborated by image analysis. These findings were interpreted as a localized hypertrophy of astroglia caused by the anterograde degeneration of geniculocortical terminals. This hypertrophy is accompanied by an increase in GFAP, which may represent the stabilization of the cytoskeleton of newly formed glial processes involved in the rearrangement of the impaired neuropil.

Afferent Pathways↗

PubMed1990

Vasoactive intestinal polypeptide (VIP) containing cells in the developing rat occipital hemisphere.

Numerous cells were observed to show intense vasoactive intestinal polypeptide (VIP) immunoreactivity from birth to postnatal day 8 in the subventricular zone of the rat occipital hemisphere. This cell population was markedly reduced by postnatal day 8, but isolated clusters of VIP cells persisted into adulthood. In addition, long, L-shaped VIP fibers were seen in the hemispheric wall up to postnatal day 16, but not in the adult. Parallel to the reduction in number of the subventricular VIP cells an increasing number of VIP cells appeared in the neo- and allocortex, developing by postnatal day 12 all the features of the mature cortical bipolar fusiform neurons. As possible alternatives, the migration of subventricular VIP cells into the cortex, the transient character of the subventricular VIP population or the expression of VIP by radial glia are discussed.

Aging↗

PubMed1989

Immunohisto- and cytochemical localization of cortical nicotinic cholinoceptors in rat and man.

A monoclonal antibody (WF 6) raised against purified Torpedo nicotinic acetylcholine receptor was applied to study the cellular and subcellular receptor distribution in human and rat neocortex. In both species, immunostaining was most prominent in perikarya and dendrites of the projection neurons in layers III and V. In layer VI fusiform cells displayed immunoreactivity while in layers I, II and IV some round-shaped cells were immunostained. Subcellularly, immunoprecipitate was found in neuronal perikarya, dendrites and in the postsynaptic thickenings, indicating intracellular sites of synthesis, transport and membrane incorporation of receptor protein. The results suggest that WF 6-immunocytochemistry is a useful tool to label nicotinic cholinergic receptors rendering new information about the specific cell-type and subcellular receptor distribution hardly obtainable by using conventional receptor autoradiography.

Adult↗

PubMed1989

Nerve endings from rat brain tissue release copper upon depolarization. A possible role in regulating neuronal excitability.

Membrane vesicles from rat cerebral cortex were prepared and the functional response of the GABAA receptor was followed by monitoring GABA-activated influx of the radiotracer 36Cl- ion. CuCl2 decreased GABA-activated 36Cl- influx into synaptosomal membrane vesicles. The effect of Cu2+ was concentration dependent (5-500 microM CuCl2) and occurred with saturating (1 mM) as well as low (30 microM) GABA concentrations. A similar inhibition of the responses to muscimol (30 microM) was also observed with 50 microM CuCl2. In addition, release of copper from cortical synaptosomes and median eminence was followed by atomic absorption technique. An increased release of copper into the extracellular space was observed upon depolarization with 50 mM K+. A minimal concentration of copper was estimated to be 100 microM in the synaptic cleft. These findings suggest that copper may play a role in regulating neuronal excitability.

Animals↗

PubMed1989

Distribution of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the rat brain. I. Forebrain.

In the first of two papers dealing with the distribution of glial fibrillary acidic protein-(GFAP)-immunoreactive elements in the rat brain, the localization of immunostaining in the forebrain is systematically described. While the limbic cortex was found to contain intensely stained, evenly distributed astrocytes, the neocortex showed clearly stratified GFAP-staining, with substantially less immunoreactivity occurring in the middle layers than in the areas close to the brain surface or the white matter. A remarkably regular staining pattern was observed in the hippocampus and dentate gyrus. The striatum remained unstained in sharp contrast to the pallidum. In the diencephalon, the main thalamic nuclei were poor in GFAP-labelled elements in contrast to the internuclear border zones. In the hypothalamus, nuclei were conspicuous by their GFAP-staining. A consistent differential staining pattern was obtained in the epithalamic structures. The observed distributional pattern of diencephalic GFAP-immunoreactivity is thought to be due to different regional proliferation of the embryonic neuroepithelium of the diencephalon. The uneven distribution of GFAP-immunoreactivity in the forebrain is explained on a mainly developmental basis.

Animals↗

PubMed1989

Distribution of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes in the rat brain. II. Mesencephalon, rhombencephalon and spinal cord.

The topographical mapping of glial fibrillary acidic protein (GFAP)-immunoreactivity was performed in coronal serial sections of the rat mesencephalon, rhombencephalon and spinal cord. Relative to a background of poor or moderate overall staining of the mesencephalon, the interpeduncular nucleus, substantia nigra and the periaqueductal grey matter were prominent by their intense GFAP-immunoreactivity. The pons and particularly the medulla contained more GFAP-labelled elements compared with the mesencephalon. The spinal trigeminal nucleus and Rolando substance were distinguished by their intense staining. Large fibre tracts were usually poor in immunoreactive GFAP. In a concluding discussion, findings relevant to the GFAP-mapping of the whole rat CNS are evaluated with regard to possible reasons underlying the observed differential distribution of GFAP-immunoreactivity.

Animals↗