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Biomedical subjects

J Sievers

Publications and source records attributed to J Sievers.

At least 91 records · Page 5Linked to original sources
PubMed1980

Structural and biochemical changes in rat cerebral cortex after neonatal 6-hydroxydopamine administration.

Newborn rats received an intracisternal injection of 6-hydroxydopamine (100 micrograms) within 16 h after birth. Treatment effects upon noradrenaline uptake (with or without desmethylimipramine pre-incubation), endogenous noradrenaline, dopamine, and serotonin were biochemically assayed. Noradrenaline uptake and endogenous noradrenaline content were permanently reduced to less than 5% of control values. Reduction of endogenous dopamine content was less marked: at day 60, values were about 40% of controls. Serotonin content remained unaffected. Cell density countings in postnatal day 15 temporal cortex revealed an about 16% reduction in layers II and III of treated animals. These modifications of cortical geometry were discussed with reference to measurements of cortical thickness and ultrastructural observations on postnatal days 2, 5 and 15. Both supranormal involution and growth processes might result from the neurotoxin treatment. Whereas some of the degeneration processes might be due o general cytotoxic effects, this is less likely for the supranormal growth processes.

Animals↗
PubMed1979

Studies on the dense-core vesicles in the ontogenesis of locus coeruleus. III. Statistical reconstruction of the diameter distribution of the dense-core vesicles in locus coeruleus during rat ontogenesis.

The method for statistical reconstruction of the diameters of dence-core vesicles, described in the previous work, is applied for studying the changes of these vesicles in the perikarya, the axonal boutons and the neuropile of the rat locus coeruleus during ontogenesis. The data obtained show the presence of the population during the embryonal development and of two populations of dense-core vesicles after birth in the structures studied. This finding is interpreted in connection with the different function of the dense-core vesicles and of the transmitters, respectively, in the development and function of the main noradrenergic nucleus in the brain of mammals -- locus coeruleus.

Age Factors↗
PubMed1978

Studies on the dense-core vesicles in the ontogenesis of locus coeruleus. I. Localization, type and density of the dense-core vesicles in locus coeruleus during rat ontogenesis.

In an attempt to clarify the function of dense-core vesicles quantitative estimation is made of their density and localization in the perikarya, axonal boutons and neuropil of rat locus coeruleus during different ontogenetic stages. The results obtained, compared with the fluorescence- and electronmicroscopic data, suggest participation of the dense-core vesicles in the neuronal development and differentiation: presence in the earliest embryonal periods, statistically significant increase in the density in the period of most intensified growth and maturing of the neuropil and axonal boutons, and change in the density of the perikarya in connection with intensified axonal transport. Quantitative data are also presented about the participation of the dense-core vesicles in synaptic transmission.

Animals↗