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B Lössner

Publications and source records attributed to B Lössner.

At least 37 records · Page 2Linked to original sources
PubMed1984

Changes in the incorporation of [3H]leucine into proteins of rat hippocampus subregions during the acquisition of a brightness discrimination are lateralized.

The incorporation of intraventricularly injected L-[4,5-3H]leucine into proteins of rat hippocampus subregions ("CA 1", "CA 3" and "Ca 4/area dentata") was studied during the acquisition of a footshock-motivated brightness discrimination. In passive controls, protein synthesis rates in CA 3 was significantly increased over those of CA 1 and CA 4/area dentata. Moreover, in left CA 3 L-leucine incorporation rates were significantly elevated when compared to those of the controlateral side. These differences between hippocampus subregions and left and right CA 3 were found to be not dependent on the technique of L-leucine application, but left-right differences did not exist under in vitro conditions. During training, protein synthesis rate in right CA 3 was increased by about + 30% (p less than 0.05) over that of active or passive controls. The trend in CA 1 was not significant. Protein labelling in left hippocampal subregions and, in addition, right CA 4/area dentata exhibited no differences between trained and non-trained animals. Pretreatment of rats with uridine-5'-phosphate improving long-term memory formation resulted in an augmentation of L-leucine incorporation into proteins of CA 1 and CA 3 of trained animals when compared to controls, whilst in other hippocampal subregions no differences in incorporation rates were found between trained and nontrained rats. The present data provided evidence for a hemispheric asymmetry of training-induced changes in protein synthesis in CA 1 and CA 3 of rat hippocampus.

Animals↗
PubMed1983

Changes in activities of fucokinase and fucosyltransferase in rat hippocampus after acquisition of a brightness discrimination reaction.

Activities of enzymes involved in utilization of the glycoprotein precursor L-fucose (fucokinase and fucosyltransferase) were studied in rat hippocampal tissue after acquisition of a brightness discrimination reaction. Fucokinase activity was increased immediately after training, while fucosyltransferase revealed decreased values. However, 7 hr after training fucokinase activity showed normal values, while fucosyltransferase activity rose in trained animals over active and passive controls. The results are discussed in the light of a regulatory role that fucokinase and fucosyltransferase may play in fucose utilization under altered functional conditions.

Animals↗
PubMed1983

Passive avoidance training increases fucokinase activity in right forebrain base of day-old chicks.

Fucokinase (EC 2.7.1.52) activity was estimated in supernatants of homogenate from day-old chick forebrain. Enzyme kinetic studies gave a Km of 4.5 X 10(-6) M and Vmax of 3.72 nmol fucose converted into fucose-1-phosphate/mg prot/h. The pH optimum was 7.5. The enzyme is thus considerably more active than was reported for other species and tissues. There were no differences in enzyme activity between the four forebrain regions studied. One hour after chicks were trained on a one-trial passive avoidance learning paradigm, enzyme activity in the right forebrain base increased 14% over control values (p less than 0.02). The 11.3% increase in activity in the left forebrain base and 10.3% increase in the left roof were not statistically significant. The relationship of this change to the increased fucose incorporation into glycoproteins known to occur over a similar time period and the significance of the lateralization of the increase are discussed.

Animals↗
PubMed1983

The effect of dopamine on L-fucose incorporation into hippocampal and striatal slices of dopamine-supersensitive rats.

The incorporation of L-[1-3H]fucose into total proteins was measured in hippocampal and striatal slices of dopamine-supersensitive and control rats. Compared with controls, striatal slices of supersensitive animals exhibited an augmented stimulation of L-fucose incorporation by 5 X 10(-5) M dopamine. This result supports former data about a dopamine-receptor mediated regulation of protein glycosylation in the nervous tissue.

Animals↗
PubMed1983

[Behavior of plasma amino acids in alcohol-induced chronic liver diseases].

In chronic liver diseases of alcoholic and non-alcoholic origin there are strikine differences of aspartate, glutamate and prolin. Where as plasma levels of aspartate and prolin are in most cases higher than in non-alcoholics, glutamate shows a contrary behaviour except in hepatic coma. The plasma ratio of alpha-amino-butyric acid to leucin allows no distinction of alcoholic from non-alcoholic liver lesion.

Adult↗
PubMed1982

Mechanisms of dopamine induced changes in hippocampal glycoprotein metabolism.

In rat hippocampal slices incubated in the presence of dopamine, a relatively strong correlation was observed between changes in the incorporation of 3H-fucose into total proteins and the formation of GDP-3H-fucose. However, in hippocampal homogenate the incorporation of 14C-fucose from GDP-14C-fucose was not stimulated by dopamine. In contrast, the incorporation of 3H-fucose was stimulated by dopamine to a similar extent observed in hippocampal slices. Furthermore, in hippocampal slices dopamine did not increase the activity of fucosyltransferase. These results, together with our previous findings, suggest that the increased incorporation of fucose induced by dopamine in the hippocampal slices may be due to a receptor-mediated cAMP-dependent regulation, which controls the rate of fucosylation of acceptor-glycoproteins either at the level of fucose phosphorylation or of formation of GDP-fucose rather than the activity of fucosyltransferase.

Animals↗
PubMed1981

Dopamine induced changes in L-fucose incorporation into proteins of rat hippocampus and corpus striatum during postnatal development.

In 60 day old (adult) male Wistar rats dopamine caused a dose-dependent increase of L-fucose incorporation into total proteins of both hippocampus and corpus striatum slices up to +47.8 +/- 6.0% (n=6) and +53.2 +/- 8.5% (n=20), respectively, when compared to corresponding controls. Under these conditions the dopamine concentration leading to a maximum stimulation of fucose incorporation was 5 X 10(-4) M in hippocampus and 1 X 10(-3) M in corpus striatum. In the latter tissue the range of dopamine concentrations causing a significant elevation in incorporation rates was larger than in hippocampal tissue. In the corpus striatum of 9 day old rats dopamine was ineffective, but by 30 days the transmitter stimulated fucose incorporation rate reached the maximum observed for any age studied. This developmental pattern seems to be related to the ontogenesis of dopamine receptor sites or dopamine sensitive adenylate cyclase formation in this brain structure. In the hippocampus the postnatal development of dopamine induced augmentation of glycoprotein synthesis showed a longer latency, but the maximum effect was also seen in 30 day old animals. These results support our assumption that at the end of the postnatal differentiation period the glycoprotein synthesis in brain tissue may be controlled (at least to some extent) by the state of dopaminergic receptors and/or of dopamine sensitive adenylate cyclase.

Animals↗
PubMed1980

The influence of dopamine on the incorporation of different sugars into total proteins of hippocampal slices.

Dopamine increases the incorporation of L-fucose and of D-mannose to a similar significant degree, whereas the incorporation of D-galactose as well as of N-acetyl-D-glucosamin into the total proteins of hippocampal slices was only slightly enhanced. The incorporation of N-acetyl-neuraminic acid was not influenced by dopamine. The results suggest that the effect of dopamine on glycoprotein formation seems mainly to depend on the kind of nucleotides necessary for activation of sugars and not on the sugar's final position in the glycan chain.

Animals↗
PubMed1980

Effect of L-fucose on brain protein metabolism and retention of a learned behavior in rats.

The intraperitoneal or intraventricular application of L-fucose (100 mg/kg or 75 microgram, respectively) prior to training in shuttle box avoidance as well as in shock-motivated brightness discrimination in rats significantly improved the retention of learned behavior 24 hr later. The application of D-fucose was without influence on retention. In naive animals, intraventricularly applied L-fucose (75-200 microgram) caused an increase in the rate of protein synthesis in the hippocampus, resulting in a significant increase in total proteins of this brain structure, mainly attributed to the Tris-insoluble protein fractions. The results are discussed in terms of an activation of glycoprotein formation by increasing supply with L-fucose.

Animals↗
PubMed1980

Apomorphine and glycoprotein synthesis in rat hippocampus.

Apomorphine intrahippocampally injected at a dose of 5 microgram led to a significant increase in incorporation of (3H)-fucose into total proteins of this brain area, whereas 40 microgram led to a significant decrease in comparison to controls, providing further evidence for the existence of dopaminoceptive structures in the hippocampus of rats and their significance for glycoprotein metabolism.

Animals↗
PubMed1979

The influence of cholinergic transmitter substances on the incorporation of (14C)-leucine and (3H)-fucose into the total proteins of hippocampus in vivo and in vitro.

The incorporation of (14C)-leucine into the total proteins of the hippocampus is inhibited by high concentrations of cholinergic agonists, with nicotinic substances (such as 1,1-dimethyl-4-phenyl-piperazine) being more effective than muscarinic compounds (such as arecoline and pilocarpine). Under these conditions the incorporation of (3H)-fucose is not influenced.

Animals↗
PubMed1979

Dopamine and macromolecule synthesis in rat hippocampus.

In hippocampus slices both dopamine and apomorphine lead to an increased incorporation of (3H)-fucose into total proteins, whereas the incorporation of (14C)-leucine was unchanged or decreased, respectively. Noradrenaline did not alter the incorporation of both precursors, whereas haloperidol partially reduced the dopamine induced increase in incorporation of fucose. Thus, an induction process of the observed macromolecular changes involving dopaminoceptive structures of hippocampus can be assumed.

Animals↗
PubMed1978

Hippocampal activation and incorporation of macromolecule precursors.

The effect of rhythmic slow wave activity (theta rhythm) on the incorporation of 3H-leucine and 3H-fucose into the total proteins of different hippocampus areas was studied. The theta rhythm was elicited by electrical stimulation of medial septum nuclei. An increase in 3H-leucine incorporation into the total proteins of CA 3 and CA 1 sectors of the hippocampus was observed, whereas the stimulation had no influence on precursor incorporation into the complex CA 4/area dentata. In contrast to these findings 3H-fucose incorporation into hippocampal proteins was not influenced by electrical stimulation of the medial septum. These findings are discussed in comparison to the results obtained in a learning experiment, which revealed an increased incorporation of both leucine and focuse into hippocampal proteins.

Animals↗
PubMed1978

[Quantitative electron microscopic studies of the environment dependent differentiation of synapses in the hippocampus (CA 1) of the rat].

The influence of environmental factors on synaptogenesis in the rat hippocampus (stratum radiatum of CA 1) was studied by the aid of quantitative electron microscopy. Three groups of newborn Wistar-rats were exposed to different environmental conditions (sensory deprivation and stimulation, respectively). The first group was raised in complete darkness while the second was exposed to permanent noise. The third group (controls) was reared under normal laboratory conditions. The animals were sacrificed either on the 15th or on the 35th postnatal day and prepared for electron microscopy. In the 15 day old dark raised animals the number of synapses in the stratum radiatum of CA 1 was significantly decreased by 24% in comparison with the normal. On the other hand, 15 day old rats exposed to permanent noise exhibit significantly more synapses (+ 28%) in the stratum radiatum of CA 1 (the mean number of synapses/25 micrometer 2 is 4,30 +/- 1,85 in the controls, 3,29 +/- 1,66 in the dark raised group and 5,52 +/- 2,35 in the animals subjected to permanent noise). No significant differences in the number of synapses between experimental animals and controls could be found in 35 day old rats. In accordance with earlier studies on the development of dendritic spines in hippocampal neurons the results of the present paper indicate an environment-dependent differentiation of synaptic structures in the hippocampus of the rat during the early postnatal period.

Animals↗
PubMed1977

[Amino acid determination in amniotic fluid and plasma during normal pregnancies and suspected intrauterine growth retardation].

Report is made on the determination of 14 amino-acids in amniotic fluid and maternal plasma with normal pregnancy and with the presence of a fetal growth retardation. Mean values of 9 amino-acids determined in amniotic fluid with pregnancies and with a nutritive placental insufficiency are blow the mean values with normal pregnancies. These investigations are deemed as preliminary for treating small-for-dates fetus by injections of amino-acids into the amniotic sac.

Amino Acids↗
PubMed1977

[Uptake of (3H)-leucine into the total proteins of various Sommer's sectors of the rat hippocampus in vivo and in vitro].

The incorporation of 4.3-3H-L-leucine into total proteins of different Sommer's sectors of the rat hippocampus was studied. The labelling of the acid-soluble supernatant purified through anion exchanger, the specific activity of the proteins and the relative specific activity of the proteins following intraventricular and intraperitoneal application of 3H leucine were determined in vivo and, on hippocampal slices, in vitro. It has been consistently demonstrated in all experimental models that leucine is incorporated into total proteins of the hippocampal structures to a varying degree, the highest label being observed in the region "CA3". The findings seem to reflect differences in the protein synthesis of the individual hippocampal sectors. However, this conclusion was possible only on the basis of resuls taken as a whole, since each experimental model was afflicted with different methodical drawbacks limiting the interpretation of the results obtained.

Animals↗
PubMed1975

[Micromethod for the quantitative determination of leucine from biological experimental material using a dansylation technic].

A method is described allowing quantitative determination of leucine from biological material up to 1 - 10(-11) M by means of dansylation of amino acids and their thin-layer chromatographic separation on polyamide microfoils. By selecting [14C]-U-L-leucine as an 'internal' standard, which is added to the tissue during the homogenization procedure, it is possible to correct for data scattering related to variations of the conversion rate or the yield of the dansylation reaction, and to losses in the different steps of thin-layer chromatography that are difficult to standardize.

Animals↗