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N Halász

Publications and source records attributed to N Halász.

At least 37 records · Page 2Linked to original sources
PubMed1981

Immunohistochemical identification of two types of dopamine neuron in the rat olfactory bulb as seen by serial sectioning.

Several neurons around the glomeruli in the rat olfactory bulb contain the enzyme tyrosine hydroxylase as revealed by light and electron microscopic immunohistochemistry. Electron microscopic analysis of serial sections reveal that both superficial tufted cells and small periglomerular neurons were labelled. These results give further support for the view that dopamine neurons in the rat olfactory bulb, from a neuroanatomical point of view, do not represent a homogeneous cell population. Furthermore, taken together with previous results in the literature our findings indicate that, from a transmitter histochemical point of view, neither tufted cells nor periglomerular neurons represent a homogeneous cell population.

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PubMed1981

Immunohistochemical studies on the effect of capsaicin on spinal and medullary peptide and monoamine neurons using antisera to substance P, gastrin/CCK, somatostatin, VIP, enkephalin, neurotensin and 5-hydroxytryptamine.

After neonatal treatment of rats with capsaicin, the spinal cord, the spinal trigeminal nucleus and spinal and trigeminal ganglia were analysed with immunohistochemistry using antisera to several peptides and 5-hydroxytryptamine. A marked decrease was observed in substance P-, cholecystokinin-, somatostatin- and VIP-like immunoreactivity present in the central branches of primary sensory neurons in the spinal cord and in substance P- and somatostatin-like immunoreactivity in sensory ganglion cells. No definite depleting effect of capsaicin could be established on 5-hydroxytryptamine and peptides, such as enkephalin and neurotensin, present in centrally originating fibres in the dorsal horn of the spinal cord. The results demonstrate that the effects of capsaicin are not confined to substance P immunoreactive primary sensory neurons. The possibility is discussed that capsaicin effects specifically functioning rather than chemically specific primary sensory neurons.

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PubMed1981

Histamine in brain capillaries.

A high amount of histamine was found in capillaries isolated by subcellular fractionation from the brain. In view of the important effects of histamine on vascular permeability in peripheral vessels, it was thought that histamine had a similar function in the cerebral vasculature. Intracarotic histamine infusion resulted in an enhanced pinocytosis of endothelial cells and te oedematous swelling of the astrocytic end-feet system. [3H]-Histamine, injected in the cerebral ventricles, accumulated in the capillary wall. Histamine and cimetidine activated hydroxyfatty acid and prostaglandin D2 synthesis in isolated brain capillaries. The possible function of the capillary histamine in the regulation of permeability of microvessels is discussed.

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PubMed1979

The zinc iodide-osmium (ZIO) reaction in the central nervous system: localization and relations to functional activity.

The fine structural characteristics of ZIO reaction was studied in the cerebral and cerebellar cortex and olfactory bulb of the rat and in synaptosomes prepared from rat cerebellar cortex. It was concluded that: 1. Organelles of different nerve cell types exhibit different ZIO reactions provided that the impregnation was carried out under standardized conditions. 2. 6...10 times more synaptic vesicles were stained by ZIO in the inhibitory terminals than in the excitatory ones. 3. ZIO positivity was found in all types of synaptosomes prepared from cerebral cortex. Following electrical or chemical (KCl) depolarization there was a decrease in the number of ZIO positive synaptic vesicles, which decrease was directly proportional to the parameters of stimulation. 4. By x-ray microanalysis Os, Zn and Ca were consistently detected in the ZIO precipitates. Iodine, however, could not always be found. After stimulation the presence of Ca was observed even in those synaptosomes in which the ZIO reaction product was absent. 5. On the basis of the staining characteristics the reaction, under standard conditions, can reflect certain functional states of the nerve terminals.

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PubMed1978

Transmitter histochemistry of the rat olfactory bulb. II. Fluorescence histochemical, autoradiographic and electron microscopic localization of monoamines.

The rat olfactory bulb was studied with the Falck-Hillarp formaldehyde fluorescence technique, including recent modifications, autoradiography and electron microscopic cytochemistry (permanganate fixation). Some periglomerular cells and few superficial tufted cells take up and accumulate catecholamines and precursors. They probably represent dopamine cells. In the glomeruli, probable 5-hydroxy-tryptamine nerve terminals could be identified. In the granular and external plexiform layers, noradrenaline axon terminals were present. At the ultrastructural level, monoamine boutons were in synaptic contact with dendritic spines of granule cells and in the glomeruli, probable 5-hydroxytryptamine boutons formed synapses with periglomerular cell dendrites. Therefore, monoamine afferents to the bulb may exert their influence via interneurons.

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PubMed1978

Studies on the fine structural localization of zinc iodide-osmium reaction in the brain. III. Some characteristics of localization in the synaptosomes.

Synaptosomes from rat cerebral cortex were impregnated in the zinc iodide--osmium (ZIO) solution. The fine structural localization of the ZIO impregnation product was studied and, in addition, the function-dependent features of the reaction were examined after electrical stimulation or potassium chloride treatment. It was revealed that: (i) Aldehyde prefixation resulted in an increase in the number of reactive synaptic vesicles in all types of synaptosomes; (ii) Electrical stimulation decreased the number of reactive vesicles in a voltage dependent manner; (iii) Potassium chloride treatment also reduced the reactivity of vesicles; the reduction was dependent on the concentration of potassium and duration of treatment; (iv) Experimental interventions leading to the release of neurotransmitters from the synaptic vesicles and to fatigue of the nerve terminals also resulted in a decrease of the ZIO-reaction product of synaptic vesicles in a manner proportional to the strength of stimuli.

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PubMed1977

Transmitter histochemistry of the rat olfactory bulb. I. Immunohistochemical localization of monoamine synthesizing enzymes. Support for intrabulbar, periglomerular dopamine neurons.

The rat olfactory bulb was studied at the light and electron microscopic level with the indirect immunofluorescence technique and the unlabelled antibody enzyme method (PAP-technique), respectively. Antibodies to all 4 enzymes in the catecholamine synthesis were used. In the principal bulb the first two enzymes, tyrosine hydroxylase (TH) and DOPA decarboxylase (DDC), but not dopamine-beta-hydroxylase (DBH), were present in a proportion of periglomerular cell bodies and dendrites indicating that these neurons synthesize dopamine (DA). This amine may therefore be released as a transmitter substance at some of the intraglomerular dendrodendritic synapses which periglomerular cells form with the mitral cells. There is evidence to suggest that some periglomerular cells use GABA as their transmitter. Thus, a morphologically and physiologically homogenous population of neurons can be subdivided on the basis of transmitter histochemical criteria. There was an impression of more DDC-positive than TH-positive fibers in the glomeruli. Such presumably DDC-positive, but TH-negative processes may represent 5-hydroxytryptamine (5-HT) nerve terminals. DBH-positive fibers were seen in the granular, external plexiform, and very rarely, in the glomerular layers, probably representing noradrenaline (NA) nerve terminals ascending from the lower brain stem. Weakly fluorescent DDC-positive fibers may represent nerve terminals of ascending 5-HT neurons. No phenylethanolamine-N-methyltransferase (PNMT)-positive neurons were observed.

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PubMed1977

Incorporation of H3-leucine in the mouse kidney in thrombocytopenia. Attempt to demonstrate thrombopoietin production.

Light and dark field autoradiography of semithin sections prepared 6 h after a treatment with APS showed that the incorporation of H3-leucine into the cells of the convoluted tubules of the kidney was increased in mice. There was no difference in the H3-leucine incorporation in the liver, either in thrombocytopenic or in untreated animals. The increased incorporation of leucine in the kidney in APS-induced thrombocytopenia showed coincidence with increased thrombopoietin production.

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PubMed1974

Studies on the fine structural localization of zinc-iodide-osmium reaction in the brain. II. Some characteristics of localization in certain identified synapses.

Samples of the olfactory bulb and cerebellar cortex from rats were impregnated in zinc-iodide-osmium (ZIO) solution. The fine structural localization of ZIO impregnation product was studied and, in addition, the percentage distribution of ZIO-positive synaptic vesicles was ascertained in certain synapses of known function. Spherical vesicles, particularly in aldehyde-prefixed material, were found to be more resistant to ZIO impregnation than ovoid vesicles, both in dendro-dendritic and in axo-dendritic synapses. The different ZIO reactivity of synaptic vesicles in excitatory and inhibitory synapses, apart from reflecting an important difference in the chemical composition of synaptic vesicles, may offer a new method for characterizing synapses in relation to certain functions.

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