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Biomedical subjects

H Matthies

Publications and source records attributed to H Matthies.

At least 163 records · Page 9Linked to original sources

[Biochemical studies on histones of the central nervous system. II. Acetylation of histones from neurons and glia of the rat brain in vitro].

There are no qualitative differences in the electrophoretic patterns of histones from neurones and glia. A 25% increased acetylation rate is found in neuronal histones as compared to glial histones after incubation of chopped brain in a [14C]-acetate containing medium. This result probably reflects different condensation states of the chromatins of both cell types, as demonstrated by electron microscopy.

Acetates↗

[Biochemical studies on histones of the central nervous system. III. Incorporation of [14C]-acetate into the histones of different rat brain regions during a learning experiment].

Long term memory formation obviously is accompanied by changes in macromolecule synthesis within the brain structures involved. The regulation of this process was investigated in various rat brain regions using the model of histone acetylation with [14C]-acetate during the training session, as well as 5 min and 120 min upon completion of training. Almost at all three times and in most brain structures the acetylation rate was diminished in trained animals as compared to pseudo-conditioned rats. With the exception of hippocampus labeling in trained animals was even lower in comparison to passive controls.

Acetates↗

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↗

Influence of post-training intrahippocampally applied oxotremorine on the consolidation of a brightness discrimination.

The posttraining intrahippocampal injection of oxotremorine revealed an improvement of the retention performance in a brightness discrimination task. The oxotremorine effect seemed to be dependent on distinct variables of training and was restricted to rats exhibiting a good acquisition performance. Scopolamine impaired the retention performance of animals with few training errors. The role of hippocampal cholinergic synapses for consolidation was discussed.

Animals↗

Retention improvement by topical application of uridine monophosphate into different brain areas.

This study aimed to demonstrate the effect of uridine monophosphate (UMP) on the consolidation of a brightness-discrimination reaction after topical application of this RNA precursor into the hippocampus, the neocortex or the mesencephalic reticular formation (MRF). Thirty minutes before the rats started their training in a Y-chamber, UMP was injected into each animal through cannula implanted into the particular brain area. When injected into hippocampus or MRF UMP exerted no influence on acquisition, but after epidural UMP injection an impairment of acquisition was observed. After intrahippocampal or epidural UMP application the retention test carried out 48 hour after training showed a significant improvement in retention performance, whereas UMP injection into MRF showed no influence on retention. Consequently, the retention-improving effect of UMP is probably not induced by activation of ascending neuronal systems.

Administration, Topical↗

Effects of orotic acid and pirazetam on cortical bioelectrical activity in rabbits.

In order to obtain further evidence of the pharmacological effects of retention-facilitating substances, the influence of sodium-orotate, methylglucamine orotate, and pirazetam on the bioelectrical activity of central nervous system structures were studied. Sodium orotate showed no influence on the cortical and hippocampal spontaneous EEGs of conscious nonimmobilized rabbits. The amplitude of the first surface-positive wave of the cortical evoked potential that was elicited by stimulation of tooth pulp was, however, significantly increased in long-lasting terms by both pirazetam and the two salts of orotic acid. Similarly, the three substances also influenced the changes in excitability induced by PTP of tooth pulp. The findings suggest that these chemicals facilitate in nonspecific manner responses to externally applied stimuli through central structures. The relationships between the altered stimulus response and the retention-facilitating action of these substances are discussed.

Animals↗

Time course and disposition of fucose radioactivity in rat hippocampus. A biochemical and microautoradiographic study.

Male adult rats were injected intraventricularly with L-[1-3H]fucose. At various intervals, ranging between 30 min and 11 days, one-half of the brain was prepared for microautoradiography, and the hippocampus from the other side was prepared for biochemical investigations. The TCA-precipitable proteins from the hippocampus homogenate were maximally labeled at between 8 and 24 h and remained at a high radioactivity level even 11 days after [3H]-fucose injection, the labeling being predominantly present in the solubilized insoluble proteins. Using gel electrophoretic separation, study of Tris-soluble material indicated a rapid turnover of soluble fucose-containing glycoproteins, whereas several slow-migrating bands of solubulized proteins revealed a time course suggesting the presence of fucose-containing glycoproteins with slower turnover rates. Using microautoradiography, a rapid labeling of neuronal cell bodies of the hippocampus was found, whereas the nuclei were not labeled. Perikarya were maximally labeled 4 h after [3H]fucose application. The radioactive material was continuously transported from the soma into the corresponding fiber layers, the latter being maximally labeled at a pulse interval of one day; even 10 days later a considerable amount of radioactivity could be detected in the neuropil.

Animals↗

Increased fucose incorporation into rat hippocampus during learning. A biochemical and microautoradiographic study.

The incorporation of intraventricularly infected L-[1-3H]fucose into proteins of the hippocampus and visual cortex was studied during the acquisition of a shock-motivated brightness discrimination in rats. The labeling of Tris-soluble proteins from both regions was not significantly changed during learning, whereas solubilized insoluble proteins obtained from the hippocampus revealed an increased fucose incorporation in learned animals. A significant enhanced incorporation into some distinct, slow-moving, carbohydrate-rich protein bands, separated by polyacrylamide gel electrophoresis, was observed in material from CA1 and CA3 sectors as well as from area dentata of the hippocampus formation during acquisition. The corresponding gel bands from the visual cortex exhibited no differences between trained animals and controls. Jointly performed microautoradiography showed an increased fucose incorporation into most areas of the hippocampus in learned animals compared with active and passive controls. The most significant differences were found to occur mainly in substructures consisting of densely packed neuronal cells.

Animals↗

Is actinomycin D suitable for the investigation of memory processes?

The influence of Actinomycin D (AMD) applied intrahippocampally at doses of 1-6 mug/animal, on the acquisition and retention of a shock-motivated brightness discrimination was studied on rats in a semiautomatic Y-maze. The injection of AMD 4 hr prior to training did not influence the acquisition, but causes, dose-dependent, a retention loss in relearning 24 hr after training. Twenty-eight hr after AMD application, naive rats exhibited a deterioration of acquisition performance increasing equally with the dose. At the same time, both circumscribed necroses in the hippocampus and signs of a general intoxication were observed. Considering the described pro- and retroactive effects, it is concluded that the use of the inhibitor AMD in learning experiments is not suitable to provide reliable evidence of the specific importance of the cerebral RNA synthesis for memory consolidation.

Animals↗

Influence of uridine-5-monophosphate on 3H-leucine incorporation into hippocampal neurons during learning.

The influence of UMP (injected intraventricularly) on the incorporation of 3H-leucine (injected intraperitoneally) was studied in rats using the microautoradiographic technique. Under the conditions of a brightness discrimination, the incorporation of labeled leucine into hippocampal neurons was significantly increased by UMP pretreatment, whereas under control conditions UMP caused only a tendency of increase without any statistical significance. It is suggested, that under learning conditions UMP substitution increases RNA synthesis, which would yield an enhanced protein synthesis.

Animals↗

[The effect of orotic acid and orotic acid derivatives on the in vitro differentiation of hippocampus neurons-morphometric and electron microscopic studies of ribosomes].

1. By means of electron microscopic and quantitative methods at the explantate cultures of the fetal hippocampus in vitro the influence of the orotic acid, sodium orotate and methylglucamine orotate on the neurogenesis was investigated. 2. After three days of the in vitro cultivation the neuroblasts influenced by these drugs show a smaller respectively not different degree of differentiation compared to the controls. 3. Under the influence of the orotic acid and of its derivatives the neurogenesis is significantly stimulated. The drugs produce a significant increase of the membrane-bound ribosomes and polysomes. The total number of ribosomes increases following the application of orotic acid by 20%, of sodium-orotate by 48% and of methylglucamine-orotate by 23% compared to the controls (alpha = 0,1%). 4. Sodium-orotate shows with reference to the neuronal development the clearest stimulatory effect. After 20 days in vitro the total number of ribosomes is by 60% higher at the treated cultures than in the controls. 5. The results might suggest, that an enlarged supply of the pyrimidine nucleotide via a raising of the RNA- and the protein synthesis might stimulate the development of the neuroblasts even under the in vitro conditions.

Animals↗