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E Dobó

Publications and source records attributed to E Dobó.

At least 19 recordsLinked to original sources
PubMed2004

Decreased expression of kynurenine aminotransferase-I (KAT-I) in the substantia nigra of mice after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment.

Nerve cells in the substantia nigra pars compacta (SNPC) are known to express tyrosine hydroxylase (TH). By means of light and electron microscopical immunohistochemical techniques, we have shown that the dopaminergic neurons of SNPC express also kynurenine aminotransferase (KAT-I), the enzyme taking part in the formation of kynurenic acid, a neuroprotectant which is one of the endogeneous antagonists of N-methyl-d-aspartate receptors. It was also found that microglial cells and astrocytes express KAT-I. It has been shown that the highly selective dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), widely used as a model of Parkinson's disease (PD), affects not only TH of dopaminergic neurons in the SNPC but also their KAT-I immunoreactivity as well: MPTP treatment decreased the number and optical density of KAT-I immunoreactive SNPC neurons. Decrease of KAT-I after MPTP treatment has been proved also by Western blot analysis. MPTP also reduced KAT-I immunoreactivity of microglial cells, except for those involved in reactive gliosis, which were arranged in groups surrounding affected neurons of the SNPC; also the number of KAT-I immunoreactive (IR) astroglial cells was increased in SNPC. We conclude that MPTP treatment may have a dual effect: in addition to being deleterious for neurons expressing TH and KAT-I, it also affects glial cells which could exacerbate the neurodegenerative process characterizing PD.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2001

Time-dependent distribution and neuronal localization of c-fos protein in the rat hippocampus following 4-aminopyridine seizures.

The immunohistochemical localization of c-fos protein in the CNS neurons was studied in a model of generalized epilepsy induced by the intraperitoneal injection of 4-aminopyridine to adult Wistar rats. This specific blocker of the voltage-dependent potassium channels proved to be suitable for use in the investigation of epileptogenesis. Following the treatment of adult rats with 5 mg kg of 4-aminopyridine, the animals experienced generalized seizures. At the end of the experiment, the rats were briefly anesthetized and perfused with fixative. Frozen coronal plane sections were cut and processed for immunohistochemistry, using polyclonal c-fos antibody. The number and distribution of immunostained cell nuclei in the hippocampus were analyzed in detail with the help of a digital microscope camera and a morphometry program. The highest level of immunostaining was detected in most of the structures at 3 h, but the level had decreased to the control level by 5 h following 4-aminopyridine injection. In the dentate fascia, immunostaining was highest at 1 h and then decreased slowly until 5 h post-injection. The activated neuronal assemblies were analyzed with the aid of parvalbumin c-fos double immunostaining. These countings revealed the highest inhibitory interneuronal activation in every part of the hippocampus (including the dentate fascia) at 3 h post-injection. The results indicate that systemic 4-aminopyridine induces limbic seizures, which are probably initiated in the entorhinal cortex.

4-Aminopyridine↗
PubMed1999

Estrogen receptor immunoreactivity is present in the majority of central histaminergic neurons: evidence for a new neuroendocrine pathway associated with luteinizing hormone-releasing hormone-synthesizing neurons in rats and humans.

The central regulation of the preovulatory LH surge requires a complex sequence of interactions between neuronal systems that impinge on LH-releasing hormone (LHRH)-synthesizing neurons. The reported absence of estrogen receptors (ERs) in LHRH neurons indicates that estrogen-receptive neurons that are afferent to LHRH neurons are involved in mediating the effects of this steroid. We now present evidence indicating that central histaminergic neurons, exclusively located in the tuberomammillary complex of the caudal diencephalon, serve as an important relay in this system. Evaluation of this system revealed that 76% of histamine-synthesising neurons display ERalpha-immunoreactivity in their nucleus; furthermore histaminergic axons exhibit axo-dendritic and axo-somatic appositions onto LHRH neurons in both the rodent and the human brain. Our in vivo studies show that the intracerebroventricular administration of the histamine-1 (H1) receptor antagonist, mepyramine, but not the H2 receptor antagonist, ranitidine, can block the LH surge in ovariectomized estrogen-treated rats. These data are consistent with the hypothesis that the positive feedback effect of estrogen in the induction of the LH surge involves estrogen-receptive histamine-containing neurons in the tuberomammillary nucleus that relay the steroid signal to LHRH neurons via H1 receptors.

Animals↗
PubMed1993

Distribution of GABA-immunoreactive nerve fibers and cells in the cervical and thoracic paravertebral sympathetic trunk of adult rat: evidence for an ascending feed-forward inhibition system.

Neurochemical and immunohistochemical evidence suggests that the superior cervical ganglion (SCG) contains all components of a gamma-aminobutyric acid (GABA)ergic transmission system, which includes GABAergic axons of unknown origin. The number of nerve fibers with and without GABA-like immunoreactivity was determined in interganglionic connectives at all cervical and thoracic levels of the paravertebral sympathetic trunk. In addition, the distribution of GABA-immunoreactive (IR) neurons was established within the ganglion chain and compared with the relative frequency of principal neurons richly innervated by GABA-IR axon terminals. The following results were obtained: 1) the total number of nerve fibers in cross sections did not significantly vary between the cervical levels, but it increased steadily from upper to lower thoracic segments; 2) in contrast, the number of GABA-IR fibers decreased from the cervical sympathetic trunk below the SCG (approximately 300 fibers) down to the seventh to tenth thoracic ganglion, below which no such fiber was seen; 3) GABA-IR nerve fibers originate from a subclass of GABA-IR cells; these are small, bipolar neurons with predominantly ascending, unmyelinated axon-like processes; 4) the number of principal neurons richly innervated by GABA-IR nerve fibers decreased from the SCG to the upper thoracic ganglia, and was very small below; and 5) apart from basket-like innervation, GABA-IR axons also formed diffuse networks around GABA-negative principal neurons predominantly in cervical and upper thoracic ganglia. These data suggest that the GABAergic innervation of paravertebral sympathetic ganglia is more complex than previously suspected. What appears as preganglionic afferents from several spinal segments (C8-Th7) innervate GABAergic neurons in the sympathetic trunk which have ascending axons and focus their inhibitory effects on the cervical sympathetic ganglia, predominantly the SCG. These data suggest that GABAergic small interganglionic neurons form a feed-forward inhibition system, which may be driven by multisegmental spinal input in the paravertebral sympathetic ganglion chain.

Afferent Pathways↗
PubMed1993

Distinct subsets of neuropeptide Y-negative principal neurons receive basket-like innervation from enkephalinergic and gabaergic axons in the superior cervical ganglion of adult rats.

The distributions of axons immunoreactive for [Leu]- or [Met]enkephalin and GABA were studied in the superior cervical ganglion of adult rats. The antigens were visualized separately and in combination with neuropeptide Y by the immunoperoxidase technique, using reaction end-products of different colors. Similarities and differences were found in the light-microscopic innervation patterns of enkephalin- and GABA-immunoreactive nerve fibers. Both fiber systems were heterogeneously distributed within the superior cervical ganglion, forming denser networks in its rostral part than elsewhere in the ganglion. The appearance of labeled nerve fibers differed in the two systems. Enkephalin-immunoreactive axons exhibited dotted profiles due to a strong immunoreaction in the axonal varicosities as compared with that in the intervaricose segments, whereas GABA-positive fibers were evenly labeled in both parts of the axons. The most marked difference between the innervation patterns from enkephalin- and GABA-immunoreactive axons was the presence of bundles of varicose axons in conjunction with the basket-like aggregation of enkephalin-immunoreactive nerve terminals. The possibility that enkephalins and GABA are co-localized in certain axons was excluded in double-labeling studies, silver intensification being used for the first antigen and the nickel-enhanced diaminobenzidine reaction for the second antigen. Different subsets of principal neurons were richly innervated in a basket-like manner by axons immunoreactive for enkephalins and GABA. Additionally, combined staining with antisera against either enkephalin and neuropeptide Y or GABA and neuropeptide Y revealed that both subsets of principal neurons richly innervated either by enkephalin-immunoreactive or by GABA-immunoreactive axons were devoid of neuropeptide Y immunoreactivity. Thus, the enkephalinergic and GABAergic axons have different subpopulations of neuropeptide Y-negative principal neurons as targets in the superior cervical ganglion. These results provide further evidence that sympathetic ganglion cells can be classified on the basis of their receiving input from different sources.

Animals↗
PubMed1992

Termination pattern and fine structural characteristics of GABA- and [Met]enkephalin-containing nerve fibers and synapses in the superior cervical ganglion of adult rat.

Morphological features of nerve fibers and synapses containing GABA and [Met]enkephalin were studied at the light and electron microscopic levels in the superior cervical ganglia of rats by pre- and postembedding immunohistochemistry. Both GABA and [Met]enkephalin immunoreactivities were found in varicose nerve fibers, forming diffuse networks which were denser in the rostral than in the caudal part of each ganglion. For both antigens rich and basket-like innervation was observed around some of the principal neurons. The GABA-immunoreactive fibers were evenly stained, while in case of [Met]enkephalin-positive nerve fibers the varicosities showed intensive immunopositivity only. Postembedding immunochemistry revealed that both inhibitory substances were located in axon varicosities which established asymmetric synapses of Gray I type. Fine structural investigation revealed that GABA-like immunoreactivity was confined in the nerve endings to the clear synaptic vesicles of 40 nm diameter, whereas the immunogold particles, indicating the occurrence of [Met]enkephalin, were located over the large dense-cored vesicles of 120 nm diameter. The clear and dense-cored vesicles were, however, mixed in the nerve endings labeled by either neurotransmitter substance. Interestingly, the [Met]enkephalin-immunopositive axon terminals were found, consequently, in synaptic contacts with dendrites containing dense bodies in a row underlying the postsynaptic membrane thickening. Since nerve terminals with GABA-like immunoreactivity established synapses of Gray I type without such subjunctional bodies, one can reasonably assume that, in spite of similarities in termination pattern, there is no co-existence of GABA and enkephalin in the axons in the superior cervical ganglion.

Animals↗
PubMed1992

GABA-immunoreactive structures in rat kidney.

We examined the distribution of gamma-aminobutyric acid-like immunoreactivity (GABA-LI) in the rat kidney by light and electron microscopy. In vibratome sections, GABA-LI was present in both the renal medulla and cortex. The inner stripe of the outer medulla was most heavily and almost homogeneously labeled, whereas GABA-LI in the cortex was mainly confined only to some tubules. GABA-positive structures involved the epithelial cells of the thin and the thick ascending limbs of the loop of Henle, the connecting tubules, and the collecting ducts. In GABA-positive connecting tubules and collecting ducts the immunoreactivity was present in the cytoplasm of about half of the epithelial cells. As revealed by electron microscopy, the labeled cells in the collecting tubules were the light (principal) cells. No GABA-LI occurred in neuronal structures. These findings are consistent with the presence of a non-neuronal GABA system in the rat kidney. Furthermore, the specific distribution of GABA in the tubular epithelium suggests a functional significance of this amino acid in tubular transport processes.

Animals↗
PubMed1991

Releasable GABA in tubular epithelium of rat kidney.

The distribution of gamma-aminobutyric acid (GABA) in the rat kidney was examined by immunocytochemical techniques. GABA-like immunoreactivity (GABA-LI) was predominantly confined to the renal tubules, including the ascending parts of the distal tubules, and the loops of Henle, the collecting tubules and ducts, and the connective parts of the convoluted tubules. In GABA-positive cortical tubules, about half of the epithelial cells were labelled. The labelled cell type showed the ultrastructural features of principal cells. Depolarizing stimulation by ouabain and high K+ concentration evoked the efflux of endogenous GABA from kidney slices. The present findings, along with previous results, suggest that GABA released from renal tubular epithelium, and transported with the urine, might be involved in the modulation of contractility in the urinary tract.

Animals↗
PubMed1990

Structures with GABA-like and GAD-like immunoreactivity in the cervical sympathetic ganglion complex of adult rats.

The distribution of gamma-aminobutyric acid (GABA)-like and glutamate decarboxylase (GAD)-like immunoreactivity was studied in the cervical sympathetic ganglion complex of rats, including the intermediate and inferior cervical ganglia and the uppermost thoracic ganglion. GABA-positive axons may enter the ganglion complex via its caudal end. Others apparently arise from small GABA-positive cell bodies which are scattered among principal neurons, within clusters of SIF cells and in bundles of GABA-negative axons. The majority of these cells is located in the lower half of the ganglion complex. Principal neurons did not react with antibodies against GABA or GAD. An unevenly distributed mesh-work of GABA-immunoreactive axons was seen in each of the ganglia. Immunoreactive axons formed numerous varicosities. Some of them were aggregated in a basket-like form around a subpopulation of GABA-negative principal ganglion cell bodies. Electron-microscopic immunocytochemistry revealed that GABA-positive nerve fibers establish asymmetric synaptic junctions with dendritic and somatic spines of principal neurons, whereas postsynaptic densities are inconspicuous or absent on dendritic shafts and somata. The results suggest that in the cervical sympathetic ganglion complex principal neurons are not GABAergic, but are innervated by axons which react with both antibodies against GAD and/or GABA antibodies and originate from a subpopulation of small neurons.

Animals↗
PubMed1990

Demonstration of bacterial antigen in macrophages in experimental pyelonephritis.

The immunomorphological characteristics of interstitial macrophages with PAS-positive granules were studied in experimental Escherichia coli pyelonephritis in rats, using an anti-E. coli antibody. Immunohistochemical, immunoelectron microscopical, as well as light- and electron microscopical findings were compared at twelve time points between 2 days and 13 weeks after infection. Macrophages with PAS-positive granules were present in the inflammatory infiltrates from the 7th day. The granules were phagolysosomes, filled predominantly with myelin figures. The myelin figures originated mainly from the constituents of the bacterial wall and reacted with the anti-E. coli antibody even 13 weeks after infection. The storage of bacterial residues with preserved antigenic structures for several weeks after infection indicates disturbed phagolysosomal elimination of the bacterial substances in the PAS-positive macrophages. In the formation of macrophages with PAS-positive granules, lysosomal overloading with large amounts of bacteria and cell debris is assumed, leading to consumption of the lysosomal enzymes, consequent incomplete breakdown and retention of the bacterial residues.

Animals↗
PubMed1989

Pronase treatment increases the staining intensity of GABA-immunoreactive structures in the paravertebral sympathetic ganglia.

A novel tissue preparation technique for improving gamma-aminobutyric acid (GABA) immunocytochemistry has been developed. The influence of the glutaraldehyde concentration in the fixative and the effect of pronase treatment on the GABA immunostaining were tested. This method includes fixation with a high concentration of glutaraldehyde, gelatin embedding and treatment of the sections with pronase. In sympathetic (paravertebral) ganglia and their connectives, the most intense and specific immunoreaction was obtained with the following procedure: immersion fixation in 5% glutaraldehyde, infiltration and embedding in 15% gelatin, secondary fixation of the samples with 4% formaldehyde, floating frozen sections and digestion with 0.1% pronase for 15-20 min. With this technique, the GABA-containing structures (cells and nerve fibers with varicosities forming basket-like networks around some principal neurons) were selectively labeled. The data presented suggest that (1) a high concentration (5%) of glutaraldehyde in the primary fixative is necessary to preserve a large proportion of the GABA content; (2) this glutaraldehyde fixation partly masks the GABA immunoreactivity; and (3) this masking may be overcome by a proteolytic treatment preceding the immunostaining. This method has been extensively tested for the light microscopic visualization of GABA-containing tissue components in the sympathetic ganglion chain, but it may probably also be used for the immunocytochemical detection of other small molecules in other parts of the nervous system.

Animals↗
PubMed1989

Evidence for GABAergic fibers entering the superior cervical ganglion of rat from the preganglionic nerve trunk.

The origin of gamma-aminobutyric acid immunoreactive (GABA-IR) nerve fibers present in the superior cervical ganglion (SCG) of rat was investigated. With immunocytochemical techniques many nerve fibers showed GABA-like positivity in the cervical sympathetic trunk, whereas similar staining could not be revealed in the internal carotid nerve or in the external carotid nerve. Ligation of the cervical sympathetic trunk for 24 h resulted a dramatic reduction in the staining density in the ganglion and in the cervical sympathetic trunk distal to the ligature. After transection of the preganglionic nerve fibers for eleven days or more, very few fibers staining for GABA were seen in the ganglion. The immunohistochemical results suggest that a major source of GABA within the SCG is a population of GABAergic axons entering from the preganglionic trunk.

Animals↗
PubMed1989

Fibre typing using sarcoplasmic reticulum Ca2+-ATPase and myoglobin immunohistochemistry in rat gastrocnemius muscle.

Skeletal muscle fibre types were identified by using immunohistochemical detection of sarcoplasmic reticulum Ca2+-ATPase and myoglobin content in rat gastrocnemius muscle. The strong Ca2+-ATPase-reactive fibres were identical with the fast-twitch population, while the fibres with weak reactivity represented the slow-twitch type. Strong myoglobin immunoreactivity reflected the fast oxidative glycolytic (FOG) and slow oxidative (SO) types. Slight to moderate myoglobin immunostaining was found in the fast glycolytic (FG) fibres. The staining intensity of the different fibre types differed as follows: for Ca2+-ATPase FG greater than FOG greater than SO, and for myoglobin FOG greater than SO greater than FG. The immunoreactivity of Ca2+-ATPase and myoglobin were well preserved after fixation of the muscles in Bouin's solution, or in formol/acetic acid fixative, and paraffin embedding. Detection of the primary antibodies was carried out by using the avidin-biotin-peroxidase complex, and the immunogold-silver-staining methods. The latter was found to be more sensitive and suitable for postembedding ultrastructural demonstration of the Ca2+-pump enzyme on Durcupan-embedded muscles. The method, using 5 nm immunogold conjugate with silver enhancement, offered the advantages of high sensitivity and excellent visualization of the reaction product. The postembedding detection of sarcoplasmic reticulum Ca2+-ATPase also proved to be useful in the retrospective identification of the main fibre classes in human muscle biopsies.

Animals↗
PubMed1989

Application of immunogold-silver staining and immunoenzymatic methods in multiple labelling of human pancreatic Langerhans islet cells.

The use of immunogold-silver staining (IGSS) combined with immunoperoxidase and/or immunoalkaline phosphatase methods for the simultaneous demonstration of pancreatic islet cell hormones on routinely fixed paraffin-embedded human tissue sections was examined. If IGSS was applied first, the black colour of silver-enhanced colloidal gold on doubly immunostained sections contrasted with the colours of most of the chromogens used generally in the 2 immunoenzymatic methods. If IGSS was followed by immunoalkaline phosphatase and immunoperoxidase techniques in optional sequence, 3 different hormone-containing cell types could be stained simultaneously without non-specific cross-reactions. IGSS and immunoalkaline phosphatase methods, together with 2 kinds of non-cross-reacting immunoperoxidase systems, permitted the detection of 4 distinct antigens on the same tissue section. Multiple immunohistochemical labelling of the endocrine pancreas provides an opportunity for the correct and rapid analysis of the topographic and morphometric relationships between different hormone-producing cell populations under both normal and pathological conditions. IGSS is of great potential for the simultaneous immunolabelling of antigens situated within separate cells.

Chronic Disease↗
PubMed1989

S-100 protein immunoreactivity in human islets of Langerhans.

S-100 protein-containing cells were demonstrated by immunogold silver staining in human islets of Langerhans from patients with chronic pancreatitis (CP) with (n = 6) (Group I) or without (n = 6) (Group II) diabetes mellitus, (DM) and from nondiabetic, non-pancreatic controls (n = 6) (Group III). In all three groups S-100 protein containing cells were observed in all islets of Langerhans throughout the pancreas. Quantitative analysis of cell composition of islets did not reveal significant differences in S-100 protein cell content between the three groups. When double immunohistochemical staining was used to demonstrate different endocrine cell types (insulin, glucagon and pancreatic polypeptide) and S-100 protein immunoreactive cells, the latter proved to be a distinct cell type. Somatostatin-producing cells and S-100 protein-containing cells were usually also present as two distinct cell populations, but positive staining for both S-100 protein and somatostatin was occasionally observed within the same cells.

Chronic Disease↗
PubMed1989

[Characterization of striated muscle fiber types by Ca2+-ATPase and myoglobin immunohistochemistry of the sarcoplasmic reticulum].

By the immunohistochemical demonstration of SR calcium ATPase and myoglobin a fibre classification method was developed. Fast fibres showed intense, while slow fibres weak SR calcium ATPase reactivity. Immunohistochemical reaction of myoglobin characterized the oxidative metabolic state of fibres similar to the succinate dehydrogenase (SDH) reaction. By means of SR calcium ATPase and myoglobin immunohistochemistry fibres were classified as slow oxidative (SO), fast oxidative glycolytic (FOG) and fast glycolytic (Fg) groups. The SR calcium ATPase activity of the different fibres varied in the FG greater than FOG greater than SO order, while myoglobin immunoreactivity in the FOG greater than SO greater than FG order. Both proteins studied preserved their antigenicities in Bouin's fixative or in formol-acetate and paraffin embedding. The light microscopic immunogold-silver method was found suitable also for electron microscopy. The silver intensification of small particle-size (5 nm) gold conjugate results in a reaction with the joint advantages of high sensitivity and optimal visibility. The described immunohistochemical method proved to be suitable for the retrospective differentiation of human biopsy materials.

Calcium-Transporting ATPases↗
PubMed1988

Heterogeneous distribution of GABA-immunoreactive nerve fibers and axon terminals in the superior cervical ganglion of adult rat.

The distribution of axons and axon varicosities containing GABA was studied in the superior cervical ganglion of rat by light and electron microscopic immunohistochemistry. Two different polyclonal antibodies were used, which had been made against GABA conjugated by glutardialdehyde to bovine serum albumin. GABA-like immunoreactivity occurred in many axons within the cervical sympathetic trunk and in axons and axon varicosities around the principal nerve cells in the superior cervical ganglion. GABA-positive axons were intermingled with non-stained axons, except for a small group of fibers in the trunk where the staining was absent. The rostral part of the ganglion and some scattered patches were more densely innervated by GABA-positive axons than the middle and caudal parts. Within dense areas, some of the large ganglion cells were abundantly surrounded by GABA-positive nerve fibers, while the vicinity of others was devoid of any immunoreactive axon terminals. None of the principal ganglion cells contained GABA-like immunoreactivity, although a class of small cells scattered within the ganglion was stained. Transection of the cervical sympathetic trunk for 11 days caused the disappearance of GABA-like positivity from most of the fibers, and only very little GABA-like staining was revealed in some small cells, which resembled satellite cells. Ultrastructurally, the GABA-positive nerve fibers were unmyelinated. However, their terminal branches and varicosities accumulated around the perikarya and dendrites of certain principal ganglion cells were partly wrapped in glial processes. The present results provide evidence that the superior cervical ganglion of adult rat receives a significant number of GABA-positive axons from the cervical sympathetic trunk and that these axons provide an innervation which is heterogeneously distributed within the superior cervical ganglion and on ganglionic cells. The source and function of the GABA-positive axons remain to be elucidated.

Animals↗