K. Halasy - Academia.edu (original) (raw)

Papers by K. Halasy

Hippocampus, 2004

This study examined the distribution of vesicular glutamate transporter 2 (VGLUT2)‐immunoreactive... more This study examined the distribution of vesicular glutamate transporter 2 (VGLUT2)‐immunoreactive neuronal structures in the ipsilateral and contralateral hippocampi of unilateral fimbria/fornix transected, unilateral entorhinal cortex ablated, and intact female and male rats. In the hippocampi of intact animals, the highest density of VGLUT2‐positive boutons was observed in the supragranular layer of the dentate gyrus, followed by the CA2 pyramidal and oriens layers, and the stratum lacunosum‐moleculare of the CA1 field. This staining pattern was identical both in males and in females. Electron microscopic examination revealed that the immunolabeling was confined to axon terminals forming exclusively asymmetric synaptic contacts. The quantitative analysis of the synaptic targets of VGLUT2‐positive terminals showed that in the dentate gyrus, 59% of the synaptic targets were dendritic spines, followed by dendritic shafts (22%) and granule cell somata (19%). In the pyramidal layer of ...

Brain Research Bulletin, 2006

Overexcitation of neuronal networks in some forebrain structures and pathological synchronization... more Overexcitation of neuronal networks in some forebrain structures and pathological synchronization of neuronal activity play crucial role in epileptic seizures. Seizure activity can be elicited experimentally by different convulsants. Because of various distribution of excitatory and inhibitory connections in the neocortex there might be laminar differences in seizure sensitivity. Current source density (CSD) analysis or immunocytochemical c-Fos localization offer suitable tools to localize increased activation of neurons during seizure. In the present experiments, interictal epileptiform activity elicited by 4-aminopiridine, bicuculline or Mg(2+)-free solution was recorded with a 16-channel multielectrode assembly in different layers of the somatosensory cortex, and CSDs were calculated. Parallel c-Fos immunocytochemistry was applied. Each convulsant elicited characteristic activation pattern. 4-aminopiridine induced relatively short discharges, which were associated with a huge sink in layer V, the sink and source pattern was relatively simple. Mg(2+)-free solution elicited the longest discharges, sinks appeared typically in the supragranular layers II and III than quickly distributed toward layers V and VI. Bicuculline induced rather similar seizure pattern as Mg(2+)-free solution, but the amplitudes of field potentials were larger, while the durations shorter. The peak of c-Fos activation, however, was not parallel with the largest electrical activation. Larger amount of stained cells appeared in layers II and III in 4-aminopiridine and bicuculline, respectively. In Mg(2+)-free solution the highest c-Fos activity was detected in upper layer VI. Long-lasting cellular effects do not always correspond to the largest electrical responses, which are primarily determined by the activation of asymmetrical pyramidal neurons. Interneurons, which possess more symmetric process arborisation, play less important role in the generation of field potentials, although they may be intensively activated during seizure.

ABSTRACT A szárazföldi ászkarákok morfológiai, fiziológiai és viselkedésbeli adaptációik révén so... more ABSTRACT A szárazföldi ászkarákok morfológiai, fiziológiai és viselkedésbeli adaptációik révén sokféle élőhelyen előfordulhatnak: a nedvestől a szárazig, a természetestől a zavartig. Mint talaj felszínén mozgó, röpképtelen, kisméretű gerincteleneknek igen nagy a helyhűségük. Így megjelenésük, túlélésük az élőhely adottságaitól és a fajok tűrőképességétől függ. Ökológiai jellemzőik (tolerancia viszonyaik) alapján fajaikat minősíthetjük, ami az egyes élőhelyek természetességi megítélésében segítségül szolgál. Vizsgálatainkat az Armadillidium nem négy hazai faján (Armadillidium zenckeri, A. nasatum, A. versicolor, A. vulgare) végeztük, melyek a földrajzi elterjedésükben található átfedések ellenére élőhelyi skálán jelentősen eltérnek. Az ászkarákok túlélésének szempontjából kulcsfontosságú a kiszáradás elleni védekezés. Vízháztartásuk szempontjából fontos tényező a kutikulájuk vastagsága, légzőszervük szerkezete. Kutatásunkban ezek különbségét vizsgáltuk a fajok élőhelyeinek változatossága szempontjából. Fénymikroszkópos vizsgálataink igazolták feltételezésünket: a négy faj karaktereik alapján egyértelműen elkülönül és sorrendbe állítható az élőhelygeneralista, szárazságtűrőbb A. vulgare fajtól a specialista, nagy nedvességtartalmat igénylő A. zenckeri fajig.

Journal für Hirnforschung, 1993

The dentate gyrus has been shown to receive a laminated and target selective GABAergic input (Han... more The dentate gyrus has been shown to receive a laminated and target selective GABAergic input (Han et al., 1993; Halasy and Somogyi, 1993), but the numerical parameters of this innervation are not known. In order to establish the relative weight of GABAergic inputs to the dendritic versus somatic regions of granule cells the numerical density and proportion of GABA-immunopositive and immunonegative synaptic boutons and their postsynaptic targets were determined in the molecular and granule cell layers of the dentate gyrus using the postembedding immunogold method. The granule cell layer contained 9% of all synapses with the remaining 91% being in the molecular layer. Altogether 17% of all synaptic boutons were GABA-immunoreactive, and they formed either type 1 or type 2 synaptic junctions. About 88% of synaptic boutons in the granule cell layer and 7-8% in the molecular layer were GABA-positive. However, the numerical density (number of synapses per unit volume) of GABA-immunoreactiv...

Acta biologica Hungarica, 1987

Authors studied the fine structural characteristics of the neuromuscular junctions in the aliment... more Authors studied the fine structural characteristics of the neuromuscular junctions in the alimentary tract of phylogenetically different animal species. Nearly in each studied species the so-called close contacts were observable, where the sarcolemma and axolemma establish a junction; the gap of this contact is 10-100 nm wide, and the neurotransmitters can affect the muscles through non-synaptic release (exocytosis). The junctional gap is widest in the gut wall of earthworm: 100-200 nm. Only close contacts are to be found in the alimentary canal of snail, and here, the junctional gap is as narrow as 10-15 nm. Beside close contacts synaptic neuromuscular junctions also occur in the locust gut. Their fine structural organization refer to that of chemical synapses. As in the tench intestine both striated and smooth muscular elements can be found, motor endplates as well as close contacts take part in their innervation. Only close contacts are in the smooth muscular layer of domestic fo...

Journal of neurocytology, 2000

Light microscopic analysis of the rat midbrain periaqueductal grey (PAG) showed vasoactive intest... more Light microscopic analysis of the rat midbrain periaqueductal grey (PAG) showed vasoactive intestinal polypeptide immunoreactive (VIP-ir) neurons localized at the lateral and ventral walls of the aqueduct. Some varicose VIP-ir elements were detected closely associated with the ependyma. While several VIP-ir elements were encountered immediately under the ependyma, in a few cases, VIP-ir cell bodies were seen on the luminal surface of the ependymal cells lining the aqueduct. Electron microscopy revealed that most of these cells possessed the characteristics of a local circuit neuron. All VIP-ir cells had indented nuclei. Two types were distinguished: one with rounded cell body receiving numerous axo-somatic synapses established by VIP-negative axons. The other cell type was fusiform and its surface was almost fully isolated from axonal contacts by a glial sheath. The VIP-ir processes were interconnected with other periaqueductal cells by a variety of synaptic contacts. VIP-ir axon te...

Neurobiology (Budapest, Hungary), 1998

The occurrence and distribution of four opioid peptides (methionine-enkephalin /met-enk/, leucine... more The occurrence and distribution of four opioid peptides (methionine-enkephalin /met-enk/, leucine-enkephalin /leu-enk/, dynorphin-A /dyn-A/, dynorphin-B /dyn-B/) were studied and compared in the subregions and layers of the hippocampi of four rodent species (rat, mouse, hamster and guinea-pig) by means of pre-embedding immunocytochemistry in order to reveal species-specific morphological characteristics. Concerning the mossy fibre system, in the rat met-enk and dyn-A, in the mouse met-enk, in the the hamster dyn-A, in the guinea-pig dyn-B was found to be the dominating immunocytochemically detectable hippocampal opioid peptide. Outside the mossy fibre system, in other hippocampal areas met-enk-immunopositive varicose nerve fibres were most frequently detected in the rat and mouse, whereas dyn-B was the most abundant in the guinea-pig. In the hamster hippocampus all the four studied opioid peptides occurred at least in few varicose fibres. In the rat and mouse enkephalinergic boutons...

Acta morphologica Hungarica, 1986

Innervation of the midgut musculature has been studied in the tench (Tinca tinca) by light and el... more Innervation of the midgut musculature has been studied in the tench (Tinca tinca) by light and electron microscopic methods. Smooth and striated muscle layers of the tunica muscularis of the gut are innervated by the same nerve bundles. Thick nerve bundles are found in the connective tissue between the two muscle layers projecting branches into both the smooth and striated muscle layers. The nerve fibres are varicose, the varicosities contain various vesicle populations. Some of these comprise small clear vesicles (measuring 40 nm in diameter), and a few dense-core vesicles (120 nm in diameter), while in others the amount of dense-core vesicles is higher; furthermore there are varicosities containing granules of peptidergic character measuring 200 nm in diameter. Nerve fibres often form neuropil in which synapses have not been observed. Axon terminals establish parallel membrane contacts with the muscle cells without synaptic specialization in the smooth muscle layer. Innervation of...

Zeitschrift für mikroskopisch-anatomische Forschung, 1990

The myenteric plexus of the domestic fowl (Gallus domesticus) small intestine was studied by mean... more The myenteric plexus of the domestic fowl (Gallus domesticus) small intestine was studied by means of silver staining, glyoxylic acid-induced fluorescence, the modified Koelle-Friedenwald method for the detection of acetylcholinesterase, NADH-diaphorase techniques and the unlabelled antibody method involving the use of an antiserum raised against GABA conjugated by glutaraldehyde to bovine serum albumin. The majority of the perikarya were in the ganglia, with an average density of 3370 +/- 942 nerve cells/cm2. Cholinesterase-positive and a few GABA-immunoreactive nerve cell bodies were seen in the myenteric ganglia, while fluorescent ganglion cells were not observed. In addition to AChE and GABA-positive nerve fibres, a rich fluorescent network of varicose and nonvaricose nerve fibres was detected, pointing to the presence of an extrinsic aminergic system in the domestic fowl myenteric plexus. Electron microscopic observations on nerve cells, axon profiles and varicosites with vario...

Cardiovascular Research, 2014

ABSTRACT Ophiobolins are sesterpene-type secondary metabolites, mostly synthesized by some plant ... more ABSTRACT Ophiobolins are sesterpene-type secondary metabolites, mostly synthesized by some plant pathogenic fungi (e.g. Bipolaris). Most of the microbial secondary metabolites have substantial effects on humans and animals but the background of their action is poorly known. The synapse-associated protein 97 (SAP97) anchors Kir and Kv ion channels regulating the subcellular translocation and localization of channels. The gap junction protein connexin26 facilitates direct intercellular communication but its role in the heart is indefinite. Aim: In this study we compared the expression and distribution of Kv4.x ion channels, their modulators and connexin26 in cardiomyopathic heart in the presence of ophiobolin as an external stress factor for myocytes. We used rat heart tissues and rat cardiomyocytes using molecular biology methods. Results: We revealed that the Kv4.3 pattern differs from that of Kv4.2 because only Kv4.3 marked the Z-line which is the localization place of the T-tubular system. Ophiobolin P1 (OP1) treatments down-regulated and redistributed the Kv4.2 and Kv4.3 ion channels in the plasma membrane as well as in the mitochondrial and nuclear membrane. Another effect was that the synapse-associated protein 97 did not colocalize with the Kv4.x ion channel α-subunits at the sarcolemma compared to the controls. Atomic force microscope study showed that the Young modulus and the mechanical parameters are altered on the cell surface after 1 day in the presence of OP1. The SAP97 and Kv4 channel subunits colocalize at the sarcolemma of healthy cardiomyocytes but the distribution of these complexes has changed under ophiobolin treatment. Discussion: These results suggest that the anchoring SAP97 and its modulator functions are crucial to maintain the normal ITO current in the heart tissues. In the tripartite complex of Kv4.3-SAP97-CAMKII structure are need to form the physiologically active Kv4 type channels and essential to regulate the subcellular localization of channels in the cardiomyocytes. This work was supported by grants TAMOP-4.2.2.A-11/1/KONV-2012-0035 and TAMOP-4.2.2.A-11/1/KNOV-2012-0052.

Zeitschrift für mikroskopisch-anatomische Forschung, 1988

ABSTRACT A disztrofin-disztroglikán komplexet (DGC) vizsgáltuk neuronokban és glia sejtekben. Ten... more ABSTRACT A disztrofin-disztroglikán komplexet (DGC) vizsgáltuk neuronokban és glia sejtekben. Tenyésztett Müller glia sejtekben a 71 kDa-os disztrofin forma egyik splice-variánsának (Dp71f) eloszlása független a disztroglikántól, míg az utrophin és a disztroglikán kolokalizációt mutat. A fehérjék lokalizációja és kolokalizációs mintázata hasonló nyugvó és vándorló sejtekben, és nem változik meg laminin hátására. A lamininnak a Müller glia sejtekre gyakorolt motilitásnövelő hatása jelentős részben a laminin-DGC kölcsönhatás következménye. A mozgó sejtek irányváltoztatási gyakorisága és a nyugvó sejtek nyúlvány-dinamizmusa nem függ a laminin jelenlététől. A hippocampus CA3 régiójában a Dp71f kis aszimmetrikus szinapszisok posztszinaptikus elemében, továbbá a moharostok membránján és egyes kis átmérőjű myelinhüvelyes axonokban van jelen. A Dp71f jelen van az asztrocitákban, a sejttestben és a nyúlványokban egyaránt. A fehérje a gliális fibrilláris proteint és laminint is expresszáló asztrocita populációkban fordul elő. A laterális hypothalamikus terület egyes neuronjai alfa-disztrobrevint (a-DB) expresszálnak. Az a-DB pozitív neuronok melanin koncentráló hormon immunreaktivitást mutatnak. Az a-DB a perikaryonokban és a nyúlványokban is jelen van. Az a-DB megjelenik a perivascularis glia végtalpakban, ezen belül az endothel sejteket és végtalpat elválasztó lamina basalissal érintkező membránon lokalizálódik. | Proteins of the dystrophin-associated glycoprotein complex have been localized by light and electronmicroscopic technique in neurons and glial cells. In primary cultures of retinal Muller glial cells the distribution of Dp71f, one of the splice variants of the 71 kDa dystrophin protein, has been shown to be independent of the distribution of dystroglycan, while utrophin and dystroglycan colocalized in clusters in all parts of the cells. The colocalization pattern was similar in resting and migrating cells and it was independent of the presence of laminin. The laminin-induced motility of Muller cells has been proven to be dependent on laminin-dystroglycan interaction. Dystroglycan function does not seem to be involved in the laminin-dependent increase of the direction-changing activity of the migrating cells and the process dynamism of the resting ones. Dp71f positivity has been demostrated in glial fibrillary acidic protein and laminin producing astrocytes. In the CA3 region of the hippocampus, Dp71f has been localized in the postsynaptic density of small asymmetric axospinous and axodendritic synapses. Furthermore, the protein was present on the membranes of the mossy fibers and in the axon proper of small-caliber myelinated axons. Alpha-dystrobrevin (a-DB) immunoreactivity was demonstrated on the endothelium-facing membrane of the perivascular astrocytes and in melanin-concentrating hormone producing neurons within the lateral hypothalamic area.

The Journal of Physiology, 1998

The Journal of Physiology, 2005

Pesticide Biochemistry and Physiology, 1994

ABSTRACT All parts of the carp intestine contain three different molecular forms of acetylcholine... more ABSTRACT All parts of the carp intestine contain three different molecular forms of acetylcholinesterase (AChE): G1, G4 and A12. After paraquat treatment there were no significant changes in AChE activity, whereas after CuSO4 treatment there was a slight increase in activity. During exposure of carp to 2 ppm methidathion in vivo, the AChE activity in the tissues investigated decreased significantly. Moreover, the relative distribution of the molecular forms of AChE changed relative to that in the control animals. The results suggest that an investigation of the molecular forms of fish AChE could contribute to an understanding of fish AChE at a molecular level and emphasize the importance of in vivo and in vitro approaches in assessing chemical effects and their potential hazards in the aquatic environment.