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A Csillag

Publications and source records attributed to A Csillag.

At least 55 records · Page 3Linked to original sources
PubMed1988

Cell types of the hyperstriatum ventrale of the domestic chicken (Gallus domesticus): a Golgi study.

Two major classes of neurons were observed in Golgi impregnated material of two regions of the hyperstriatum ventrale (HV) (medial and rostral HV) of the chick telencephalon: a Golgi I type neuron with long axon (putative projection neuron) and a Golgi II type neuron with short axon (putative local circuit neuron). On the basis of the nature of the axon (bifurcating or non-bifurcating, ascending or descending) and of the dendrites (spiny or aspinous, and thickness), the following subclasses (types) were identified: two long axon (projection) and three short axon (local circuit) neurons in the medial (mid-telencephalic) hyperstriatum ventrale, and one major long axon (projection) and two short axon (local circuit) neurons in the rostral hyperstriatum ventrale. Possible patterns of intraregional connections between these neurons are suggested on the basis of cytoarchitectonics. The differences in cellular types and in internal connectivity patterns strongly suggest, in agreement with physiological and behavioural observations, that the medial (mid-telencephalic) hyperstriatum ventrale distinctly differs in cellular morphology from other parts of hyperstriatum ventrale in so far as it displays a greater diversity of neuronal types with an apparent higher degree of complexity.

Animals↗
PubMed1988

Cell types of the paleostriatal complex of the domestic chicken (Gallus domesticus): a Golgi study.

A study of was carried out of Golgi impregnated material in two regions of the paleostriatal complex of the chick telencephalon, the lobus parolfactorius and paleostriatum augmentatum. As in our previous investigation of the chick medial hyperstriatum ventrale, two major classes of neurons were observed in the paleostriatum: a Golgi I type neuron (type 1) with long axon (putative projection neuron) and a Golgi II type neuron (type 2) with short axon (putative local circuit neuron). Based upon the nature of the axon (bifurcating or nonbifurcating, ascending or descending) and of the dendrites (spiny or aspinous, and thickness), the following subclasses (types) were identified: two projection and three local circuit neurons in the lobus parolfactorius and two projection and two local circuit neurons in the paleostriatum augmentatum. In addition to known differences in developmental chronology and extrinsic connectivity, the lobus parolfactorius clearly differs from palaeostriatum augmentatum in cellular composition and organization. From its cytoarchitectonic appearance we would suggest that the lobus parolfactorius is the paleostriatal region of greater complexity.

Animals↗
PubMed1988

The structure of chicken ectostriatum. I. Golgi study.

Chicken ectostriatum was studied in Golgi preparations. In the two parts of the area (ectostriatum centrale and ectostriatum periphericum) the cell types were analysed. Projection neurons with long axon, and interneurons with short axon, could be distinguished in both parts of the region. The projection neurons are different in the two parts of the area, whilst the interneurons, with regard to their morphological features, are completely similar. The stellate-like projection neurons in ectostriatum centrale have 4-6 main dendrites, which ramify only slightly, and are densely covered by characteristic spines. The projection neurons in ectostriatum periphericum emit several (7-10) main dendrites, which have numerous bifurcations establishing a dense dendritic tree. The dendrites are densely covered by regular spines. The interneurons--in both parts of ectostriatum--have three subtypes. All have characteristic local axonal arborizations with varicose terminal sections. Some quantitative parameters of Golgi impregnated neurons were also measured and analysed by computer. Preliminary results of this study are included in the present publication.

Animals↗
PubMed1987

GABAergic structures in the chick telencephalon: GABA immunocytochemistry combined with light and electron microscope autoradiography, and Golgi impregnation.

The distribution of gamma-aminobutyric acid (GABA)-ergic elements in 3 forebrain regions (medial mid-telencephalic hyperstriatum ventrale; paleostriatum augmentatum; lobus parolfactorius) of two-day-old domestic chicks was investigated using (1) light and electron microscope autoradiography following [3H]GABA uptake in vitro in combination with pre-embedding GABA immunocytochemistry and (2) Golgi impregnation and 'gold-toning' combined with postembedding GABA immunocytochemistry. In both the paleostriatal regions and the medial (mid-telencephalic) hyperstriatum ventrale, GABA immunolabelling was demonstrated with the pre-embedding technique. Radiolabelling with [3H]GABA was also shown in these regions, co-localised in many cases with the immunolabelling. In the paleostriatal regions, the majority of perikaryal labelling was found in ovoid, elongated or fusiform cell bodies of 6-7 micron diameter whereas in the medial (mid-telencephalic) hyperstriatum ventrale, larger (10-15 micron) multipolar and smaller (5-6 micron) bipolar neurons were found labelled. In the latter region, Golgi impregnated neurons of similar morphology were found to be immunopositive to GABA using the postembedding technique. The ultrastructure of [3H]GABA accumulating cells is characterised by pale or moderately granular nuclei with small invaginations, few mitochondria and a prominent Golgi apparatus. Astrocytes and ependymal cells are also labelled with [3H]GABA. GABA-labelled axon terminals represent 29-36% of the total in the 3 brain regions studied. They appear as electron-lucent boutons with few and often scattered synaptic vesicles and in most cases they form symmetrical axo-dendritic junctions.

Animals↗
PubMed1987

Alterations in synaptic structure in the paleostriatal complex of the domestic chick, Gallus domesticus, following passive avoidance training.

A morphometric study was made of synapses in both left and right hemispheres of two regions of the chick paleostriatal complex, the paleostriatum augmentatum (PA) and the lobus parolfactorius (LPO), 24 h after passive avoidance training (methyl anthranilate, M-chicks), and in water-trained controls (W-chicks). The synaptic features examined were D, the mean length of the postsynaptic thickening; Nv.syn, the numerical density of synapses; Vv.syn, the volume density of the presynaptic bouton; V, the mean volume of the presynaptic bouton; Nv.ves, the numerical density of synaptic vesicles per bouton volume; ves.syn, the number of synaptic vesicles per presynaptic bouton; and K, the curvature of the synaptic contact zone. In the LPO there is a significant increase in the numerical density of synapses (Nv.syn) in both left and right hemispheres of M-compared with W-chicks (up to 59%, depending on the method of calculation used). A hemispheric asymmetry of postsynaptic thickening length (D) which is present in W-chicks (R greater than L by 10%) is reversed in M-chicks. There is no difference in the volume density of the presynaptic bouton (Vv.syn) or the mean bouton volume (V) either between W- and M-chicks, or between left and right hemispheres. Significant changes are found after avoidance training in both of the synaptic vesicle parameters measured. There is an increase of approximately 50%, both in the numerical density of synaptic vesicles (Nv.ves) and the number of vesicles per synaptic bouton (ves.syn), in the left hemisphere of M-chicks. No changes in the mean synaptic contact curvature (K) were observed after training, either of presynaptically concave, or presynaptically convex synapses, in either left or right hemispheres, nor did the percentage distribution of these different curvature classes vary greatly. In the PA there were no significant changes in D, Nv.syn or Vv.syn, either between M- and W-chicks, or between left and right hemispheres, 24 h after passive avoidance training. However, when the differences between the mean bouton volume (V) are examined, there is a significant increase in size of the boutons in the left hemisphere of M- compared to W-chicks. There is also a hemispheric asymmetry in both Nv.ves and ves.syn in W-chicks (R greater than L by approximately 15%) and this disappears on M-training. No changes in the mean synaptic contact curvature were observed after training, either of presynaptically concave, or presynaptically convex synapses, in either left or right hemispheres. However, the percentage distribution of these different curvature classes showed some variation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Synaptic vesicle proteins and acetylcholine levels in chick forebrain nuclei are altered by passive avoidance training.

In a search for biochemical markers of modified synaptic function following training of day-old chicks on a passive avoidance task, we have assayed two monoclonal antibodies to synaptic vesicle proteins (anti-p65 and anti-SV2) and one raised to postsynaptic densities (411B). We have also measured total acetylcholine (ACh) content. Measurements were made on three forebrain regions known to show metabolic and morphological change consequent on training--the lobus parolfactorius (LPO), paleostriatum augmentatum (PA), and medial hyperstriatum ventrale (MHV)--in the right and left hemispheres 2 and 24 h after training chicks on a passive avoidance task, in which they learn to avoid pecking a bead coated with methylanthranilate [methylanthranilate-trained (M-trained)]. Control chicks were trained on a water-coated bead [water-trained (W-trained)]. Twenty-four hours after training, 411B levels showed no differences between W-trained and M-trained chicks in any region. M-training reduced the titre of anti-p65 by 16% in the left PA and 15% in the left MHV and that of anti-SV2 by 19% in the left PA. M-trained chicks showed reduced total ACh content in the LPO by up to 40% and in the PA by up to 48% but had no change in ACh level in the MHV. The decreases in antibody titre were not seen in forebrains analysed 2 h after training, but tendencies toward increases in levels in the right PA and MHV were observed with all three antibodies. Significant differences between right and left hemispheric regions, independent of training, were observed for all the antibodies and for ACh content.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1987

Importance of endogenous substrates in synaptosomal functions.

Synaptosomes were found to contain endogenous substrates in sufficient amount to support physiological ion equilibrium and to maintain the resting oxygen consumption rate. Exogenous substrates were required only in functional states which brought about an increase of oxygen consumption only in the presence of a stimulating agent. Succinate increased oxygen consumption even in the resting phase but proved to be incapable of supplying energy for synaptosomal ion transport processes.

2,4-Dinitrophenol↗
PubMed1986

Differential responses of synaptosomal cation movements and respiration to the convulsants penicillin, pentylenetetrazol and 3-aminopyridine.

The effect of three convulsants was tested in rat cortical synaptosomes by measuring Na+ and K+ movements and respiration. Penicillin (of its derivatives the 3-phenyl-5-methyl-4-isoxazolyl-penicillin, i.e. oxacillin was used) at 2 to 14 mM concentration prolonged the uptake phase of the K+-curve without altering final cation equilibrium. Pentylenetetrazol, at 10 to 50 mM exerted a concentration-dependent inhibitory effect on K+-uptake, while 3-aminopyridine was effective only at high concentrations (50 mM) preventing synaptosomal K+-uptake and increasing the synaptosomal Na+-content without, however, blocking respiration. The data suggest a transitional rise of K+-permeability of synaptosomal membrane in the presence of oxacillin, without lasting depolarization. Sufficient doses of 3-aminopyridine probably depolarize synaptosomes, the underlying mechanism probably being associated with the primary blocking of K+-channels and a subsequent increase in Na+ influx rather than with the inhibition of the Na+--K+-pump.

Aminopyridines↗
PubMed1985

Passive avoidance training results in lasting changes in deoxyglucose metabolism in left hemisphere regions of chick brain.

Day-old chicks peck when offered a bright bead; if the bead is coated with the bitter-tasting methylanthranilate (M) they avoid it thereafter. 2-[14C] Deoxyglucose injected 1 min prior to training shows increased uptake into the hyperstriatum ventrale (HV) and lobus parolfactorius (LPO) 30 min later compared with control birds which have pecked a water-coated bead (W). To distinguish effects of training from those of consolidation, and to study lateralization of the increased uptake, 2-[14C]deoxyglucose (4 muCi) was injected ip either 5 min before, or 10 or 30 min after training. Thirty minutes after injection, bilateral samples of medial hyperstriatum ventrale (MHV), LPO and palaeostriatum augmentatum (PA)-enriched regions were dissected. Specific radioactivity (dmp/mg X prot) in left and right MHV and left and right LPO was standardized on the mean PA-specific radioactivity for each bird. When 2-DG was injected 5 min prior to training, standardized radioactivity in the left LPO was 26% greater, and in the left MHV 13% greater in M than W birds. There were no differences in the right hemisphere. With injection 10 min after training, there was an increase of 22% in the left LPO of M birds over W, of 29% in the left MHV and 22% in the right MHV. If injection was delayed to 30 min after training, there was no increase in the LPO, but a 13% increase persisted in the left MHV. Enhanced 2DG metabolism following passive avoidance training is thus persistent, lateralized, and, in the MHV at least may represent an aspect of cellular reorganization consequent on experience but independent of the immediate concomitants of training--perhaps part of the process of memory consolidation.

Animals↗
PubMed1985

Comparative studies of fresh and postmortem isolated rat cortical synaptosomes: uptake and potassium-evoked release of gamma-aminobutyric acid.

Synaptosomal fractions were isolated from rat cerebral cortex immediately after decapitation and after 2 h and 4 h postmortem storage at room temperature. Uptake and release of [3H]GABA was compared between fresh and postmortem synaptosomal fractions. The results suggest that after a 2 h postmortem storage these functions are still comparable to those observed in fresh preparations, while a 4 h period of storage decreases them by about 50%. The present data are consistent with our previous findings that the 2 h postmortem fractions are comparable to freshly isolated fractions with respect to coupled respiration, potassium accumulation and capability of specific configurational changes.

Animals↗
PubMed1985

The EM autoradiographic distribution of label in tissue blocks of pallidum incorporating [3H]-Leu-enkephalin and [3H]-naloxone in vitro.

The distribution of radioactivity in pallidal tissue blocks incubated in the presence of either a tritiated enkephalin analogue or [3H]-naloxone, was examined using EM autoradiography. The quantitative evaluation was based on the principle of proportional grain counting. The results showed a preferential accumulating of silver grains over dendrites in the enkephalin-labelled tissue. Following naloxone-labelling, a slight enrichment of grains over axonal elements was found. The findings provide ultrastructural support for previous biochemical data which suggested that different types of opiate binding sites have different tissue localizations.

Animals↗
PubMed1982

The effect of gamma-aminobutyric acid on the potassium movements of rat cortical synaptosomes.

K+ fluxes of rat cortical synaptosomes were monitored by a K+ sensitive ion-selective membrane electrode. The uptake phases of K+curves from control and experimental measurements were compared and statistically evaluated. GABA significantly reduced K+ uptake but it was able to reverse the decrease of K+ uptake caused by protoveratrine. In the absence of Ca2+ the K+ uptake was diminished; GABA had no effect on this inhibition. The effect of GABA on K+ take was partially reduced by bicuculline and abolished by diamino-butyric acid. The K+ content of synaptosomes decreased, while the NA+ content increased in the presence of GABA. The results are discussed in association with presynaptic depolarisation and with modulatory effects of GABA on the release of other transmitters.

Animals↗
PubMed1982

The separation of a fraction enriched in purely inhibitory nerve terminals from rat cerebellum.

The separation of a fraction enriched in cerebellar Golgi axon terminals of well-established inhibitory nature is described. The procedure is based on the phenomenon that the incubation of cerebellar glomerulus particles (isolated by a method described earlier) in saline media leads to the selective destruction of mossy terminals and of dendrites synapsing with them, whereas Golgi axon terminals remain intact. A 60-70% enrichment in Golgi terminals was achieved as revealed by electron microscopy.

Animals↗
PubMed1981

Localization of high affinity [3H]glycine transport sites in the cerebellar cortex.

A study was made of [3H]glycine uptake sites in a preparation greatly enriched in large pieces of the cerebellar glomeruli (glomerulus particles) and in morphologically well preserved slices of rat cerebellum. Electron microscopic autoradiography revealed that of the neurones in the cerebellar cortex only Golgi cells transported [3H]glycine at the low concentration used. Glial cells also took up [3H]glycine but to a lesser extent than the Golgi neurons. It was also confirmed that under comparable conditions Golgi cells transport [3H]GABA. Kinetic studies utilizing the Golgi axon terminal-containing glomerulus particles showed that glycine is a weak non-competitive inhibitor of [3H]GABA uptake (Ki over 600 microM vs the Kt of about 20 microM) and that GABA is an even weaker inhibitor of [3H]glycine uptake. These observations indicated that glycine and GABA do not share the same carrier. Quantitative electron microscopic autoradiography showed that the uptake of the two amino acids, in terms of the unit area of labelled Golgi axon terminals, was not additive. In contrast, their uptake in terms of unit protein was strictly additive. These observations, the first relating to unit volume and the latter to the total volume of Golgi terminals, are consistent with the view that there are two biochemically separate populations of Golgi neurons, one transporting glycine the other GABA. Saturable [3H]strychnine binding was detected in the preparations of glomerulus particles, but in comparison with those from the spinal cord the affinity was lower and [3H]strychnine was not displaced by glycine. Available information on glycine receptors, however, suggest that this should not exclude the possibility of strychnine resistant glycine receptors in the rat cerebellum.

Animals↗
PubMed1981

The types of proliferating glioblasts in the immature mouse neocortex and dentate gyrus as revealed by electron microscopic autoradiography.

Proliferating glial elements of 3 to 12-day-old mouse parietal cortex and dentate gyrus were investigated by the electron microscopic autoradiography of 3H-thymidine. The presence in these regions of three types of proliferating glial precursors was verified and related to astrocyte development. Comparing the two areas studied it was concluded that postnatal glial proliferation is independent from neurogenesis and that astroglia is capable of proliferation even in advanced stages of differentiation.

Animals↗