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J Wenzel

Publications and source records attributed to J Wenzel.

At least 55 records · Page 3Linked to original sources
PubMed1982

[Effect of DL-tryptophan on photic evoked potentials and basic activity of the EEG].

The effects of DL-tryptophan on photic evoked potentials (photic after discharges--PhNE, photic recruitment--PhR, photic evoked primary potential--PhEP) and basic activity of EEG were investigated in freely moving rats with chronically implanted electrodes in various areas of cortex. DL-tryptophan increased the number of PhNE potentials and particularly the number of NE potentials per answered lightflashes (NE/bLB). The effects depend on dosage of DL-tryptophan. The double impulse stimulation confirmed these results. The power spectral show an increased synchronization of the background EEG activity. The results are discussed in connection with local serotoninergic effects and influences on vigilance by 5-hydroxytryptamine.

Animals↗
PubMed1981

[The effect of conditioning on the ultrastructural distribution of synaptic vesicles in the hippocampus of the rat].

In three months old male Wistar-rats the influence of conditioning (brightness discrimination reaction) on the number and distribution of vesicles of the synapses in the stratum radiatum (CA 3) of the hippocampus were investigated. A total of 15 rats (5 trained rats, 5 passive and 5 active controls) were studied by the aid of electron microscopic and morphometric methods. The number of synaptic vesicles was evaluated for the passive controls by 27 vesicles per synaptic area. In the CA 3-region 70 minutes after training the calculation of the number of synaptic vesicles revealed a significant decrease in comparison with passive and active controls (16 and 32 vesicles per synaptic area, respectively; significant difference at p less than 0.05). The volume of the synaptic vesicles was reduced for the trained rats by 20-25% in comparison with controls. The morphological results after training could be correlated with the changes of the Ach fractions, and seem to be of great significance at the initial stages of memory formation.

Acetylcholine↗
PubMed1981

[Electron microscopic investigations about the influence of the cyclic N6-monobutyryladenosine-3':5'-monophosphate (mb-cAMP) on the neuron differentiation in the explantate cultures of the hippocampus (author's transl)].

1. The influence of the cyclic N6-monobutyryladenosine-3':5'-monophosphate (mb-cAMP) on the neurogenesis was investigated by means of electron microscopic and morphometric methods at the explantate cultures of the fetal hippocampus of the rats in vitro. 2. After three days of the in vitro cultivation the neuroblasts of the treated cultures show not significantly changes of the total number of ribosomes in comparison to the controls. 3. After 7 and 14 days of the in vitro cultivation the neurogenesis is significantly stimulated under the influence of the mb-cAMP. The drug produces a significant increase of the free ribosomes and polysomes in company with a higher degree of differentiation of the granular endoplasmatic reticulum. Under the influence of the mb-cAMP the total number of ribosomes significantly increases by 32% (after 7 days) respectively 20% (after 14 days). 4. The results might suggest, that mb-cAMP might stimulate the protein synthesis in connection with an increased nerve fibre growth in vitro.

Animals↗
PubMed1981

[Development of neuron structure of the fascia dentata in the rat. Neurohistologico-morphometric, ultrastructural and experimental study].

In the brains of male white rats some structural parameters of granule neurons in the hippocampal dentate gyrus such as cytoarchitectonical arrangement of these cells, structure of dendrites and dendritic spines were analyzed during ontogenetic development as well as changes in these parameters due to modified external conditions (acoustic stimulation, dark rearing, cerebrolysine administration). Transmission electron microscopy as well as cytologic and morphometric methods were employed. Under normal conditions the adult cytoarchitectonical pattern of the dentate gyrus was reached at postnatal day 20 (P 20). At the ultrastructural level the differentiation of the neuronal perikarya during ontogenesis was determined by the size of the nucleus, occurrence of rough endoplasmic reticulum, ribosoms and polysoms, Golgi apparatus and mitochondria between birth and postnatal day 90 (P 0--P 90). Synaptogenesis starts in the perinatal period in form of immature axo-somatic and axo-dendritic contacts. In adults a pronounced structural variability of synapses and the presence of complex spines was found. The average density of spines increased considerably with age in isolated dendritic segments as well as over the whole length of a dendrite. The density was at P--P 2: 0,03; P 5: 0,04; P 8: 0,09; P 10: 0,1; P 15: 0,17; P 20: 0,23; P 30: 0,48; P 180: 0,62 spines per micrometer dendrite. The postnatal development of the neurons under experimental conditions was characterized by significant augmentations of the spine numbers mainly in the early postnatal phase: Controls at P 15 with 0,17, after dark rearing 0,30, after Cerebrolysine 0,32, after acoustic stimulation 0,33 spines per micrometer dendrite. At P 30 only dark rearing resulted in significant augmentation of the spine number (0,63 spines per micrometer dendrite against 0,48 in controls). The data obtained after acoustic stimulation and dark rearing point to a widespread influence of external stimuli on neuronal development not only confined to the corresponding visual or acoustic pathway. The Cerebrolysine results during early postnatal development can be explained by a stimulation of protein synthesis and, hence, of the neurogenesis.

Amino Acids↗
PubMed1980

Electron microscopic and morphometric studies on synaptic plasticity in the hippocampus of the rat following conditioning.

1. In 40 three months old Wistar rats (16 trained animals, 14 active controls, 10 passive controls) the influence of learning (brightness discrimination) on the number of electronmicroscopically detectable synapses per area neuropil was studied in the stratum radiatum (CA 1) of the hippocampus. 2. 70 minutes after completion of training, the mean number of synapses has significantly increased as compared to active controls (trained animals 14.26 +/- 2.95 synapses/25 micrometer2; active controls 10.23 +/- 2.80 synapses/25 micrometer2; p less than 0.001). 3. 24 hours after training this increase in trained animals still persisted (trained animals 14.15 +/- 2.60, active controls 11.39 +/- 2.87 synapses/25 micrometer2; p less tha 0.001). 4. 14 days after training, the number of synapses has decreased considerably, but was nevertheless significantly higher than in the active controls (trained animals 12.49 +/- 2.76, active controls 11.45 +/- 3.10; p less than 0.001). 5. The results are discussed with regard to their significance to the different stages of memory formation in the CNS.

Animals↗
PubMed1980

[Electron microscopy of the neural and synaptic organization of the regio cingularis in the rat].

The neuronal structure and synaptology of the regio cingularis of the rat was examined with electron microscopical methods. On the basis of GOLGI-impregnation studies of the cingulate region ultrastructural characteristics of pyramidal and nonpyramidal neurons were investigated concerning the variations in size and content of intracytoplasmatic organelles, morphology of the nucleus and the number, site and kind of synaptic contacts. There are mainly small and medium sized pyramidal cells. The axo-somatic synapses appear as symmetrical contacts (type GRAY II). The number and distribution of small and medium sized nonpyramidal neurons (interneurons) are different in various cortical layers. Both types of synapses, asymmetrical as well as symmetrical contacts (type GRAY I and type GRAY II) were found on the pericarya of these nonpyramidal cells. As has been established for the neocortex, the dendrites of cingulate pyramidal neurons are bundled. The numerous spines along these dendrites are of different size and shape. The asymmetric axo-spinodendritic contacts (type GRAY I) are the most frequent type of synapses compared with axo-dendritic junctions. The dendrites of nonpyramidal neurons are of the spiny type or of the sparsely spined type with dilations of "beads" (varicosities) that are present along them. The ultrastructural investigations and the results following terminal degeneration (electrolytical stereotaxic lesions in the nucleus mediodorsalis and in the nucleus anteromedialis thalami) cause the suggestion that the specific thalamic afferents reach monosynaptically the layer III or V pyramids and specific interneurons. Recurrent axon collaterals of the pyramids and inhibitory interneurons represent the morphological correlates for the recurrent inhibition of the pyramids. These results demonstrate a similarity between the cingulate cortex and the neocortex concerning the synaptic organization made up by excitatory and inhibitory neurons.

Afferent Pathways↗
PubMed1979

Herpes virus infection as a cofactor in carcinogenesis: supernatants of herpes virus type 1- and type 2-infected cell cultures contain a cell growth-stimulating factor.

Some cell cultures synthesize a mitogenic factor (DNASF) following their lytic infection with either HSV-1 or HSV-2 which is shed into the medium. Of six cell lines permissive to HSV infection tested, three produce DNASF (CV1, HF, MCA) and a significantly higher (3H)-TdR incorporation was obtained with indicator cells growing in supernatants of virus-infected cells (SupV+) than in the corresponding supernatants of sham-treated cells (SupV-). Sometimes the values obtained with SupV+ exceed those obtained with cell controls, which demonstrates that DNASF is not simply a nutritional factor. Other cell lines do not produce DNASF (HeLa, Wistar and probably REF) and SupV+ frequently inhibit cell growth. DNASF is genetically nonspecific and all indicator cells tested were stimulated by supernatants which contain the mitogen, including the nonpermissive DC-3F cells. The quantity of DNASF induced is directly proportional to the number of cells in the culture and its production peaks when the lysis of the cells is complete. It is not accumulated inside the cells.

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

Further evidence of teratogenic effects apparently produced by neurotransmitters during brain differentiation.

1. Adult male rats treated neonatally with the monoamine oxidase inhibitor pargyline showed significantly increased nuclear volumes of the nerve cells in the medial and central amygdaloid nuclei and significantly decreased concentrations of noradrenaline and dopamine in the hypothalamus as compared to control males. 2. Adult male rats treated neonatally with the monoamine depletor reserpine also displayed increased nuclear volumes of the nerve cells in the medial and central amygdaloid nuclei in comparison to the control males but significantly decreased nuclear volumes in comparison to the pargylinized males. Furthermore, the number of synapses in the stratum radiatum (CA 1-region) of the hippocampus was significantly decreased in the reserpinized males in comparison to the control males. 3. Adult male rats treated neonatally with the acetylcholine esterase inhibitor pyridostigmine showed a slight decrease of the noradrenaline concentration in the hypothalamus. These findings suggest that changes of neurotransmitter concentrations and/or turnover rates apparently produced by psychotrophic drugs during brain differentiation are able to exert teratogenic effects.

Amygdala↗