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Biomedical subjects

P Honegger

Publications and source records attributed to P Honegger.

82 records · Page 5Linked to original sources
PubMed1979

Neurotransmitter synthesis, storage and release by aggregating cell cultures of rat brain.

Rotation-mediated aggregating cell cultures of mechanically dissociated fetal (15-16 days gestation) rat brains between 25 and 35 days in vitro were examined for their ability to synthesize neurotransmitters and putative neurotransmitters from radioactively labeled precursors added to the culture medium. Cultures derived from whole brain synthesized [3H]acetylcholine from [3H]choline, [3H]gamma-aminobutyric acid from L-[3H]glutamic acid, [3H]dopamine from L-[3H]tyrosine, [3H]dopamine and [3H]norepinephrine from L-[3H]dihydroxyphenylalanine, and [3H]serotonin from L-[3H]tryptophan. Veratridine increased and tetrodotoxin decreased the rate of [3H]-dopamine synthesized by aggregates derived from midbrain plus hindbrain. In chase experiments in which aggregates were incubated for 4 h with radioactively labeled precursors and then for 4 h with non-radioactively labeled precursors, addition of veratridine (50 micronM) during the second 4 h incubation significantly decreased the amounts of radioactively labeled acetylcholine, L-glutamic acid, dopamine and serotonin recovered from aggregates. Tetrodotoxin (5 micronM) present during the chase significantly increased the amounts of [3H]acetylcholine and [3H]dopamine recovered from the aggregates. In addition, reserpine (4 micronM) markedly depleted [3H]dopamine from aggregates in these experiments. These results indicate that these cultured cells synthesized neurotransmitters and in addition suggest that some of these compounds are stored by and released from electrically active cells within the aggregates.

Acetylcholine↗
PubMed1979

Morphological differentiation of mechanically dissociated fetal rat brain in aggregating cell cultures.

Rotation-mediated aggregating cell cultures of mechanically dissociated fetal rat brains (15-16 days) were morphologically characterized at 4, 19, 26 and 40 days in vitro. The dissociated cells coalesced into spherical aggregates which increased in diameter from 340 micrometer at 4 days to 430 micrometer at 40 days. Cells within the aggregates developed from an undifferentiated state at 4 days to a population of morphologically mature neurons, astrocytes and oligodendrocytes (26 days in vitro) before degenerating. Synaptic contacts and myelinated axons appeared as the cells differentiated. Neurons tended to occur in clusters that were located in central regions of the aggregates, whereas astrocytes were more concentrated in the periphery. Synapses and myelinated axons were more abundant in central portions of the aggregates. The amount of myelin formed within the aggregates was less than in organotypic cultures or in vivo. These results show that the morphological differentiation of mechanically dissociated aggregates resembles the development of rat CNS in vitro. The ease with which large amounts of aggregates can be prepared provides an in vitro system which can be analyzed biochemically without the use of micro-methods. This advantage is particularly useful for multidisciplinary investigations in developmental neurobiology.

Animals↗
PubMed1979

The lipid composition of rat brain aggregating cell cultures during development.

The lipid and fatty acid composition of rat brain was studied during its development both in vivo and in an aggregating cell culture system. Although the amount of lipid present in the cultures was very low, the increase in glycolipid content corresponded closely to the period of intense myelin formation. Very long chain fatty acids (hydroxylated and unsubstituted) were present in 41-day cultures. In comparison to the in vivo situation, myelination was delayed in vitro and, after 40 days in culture, cholesterol esters were 5-fold higher than in vivo, indicating that demyelination was occurring.

Animals↗
PubMed1977

Biochemical differentiation of aggregating cell cultures of different fetal rat brain regions.

Rotation-mediated aggregating cell cultures of mechanically dissociated fetal rat brains divided into three (telencephalon, mesencephalon-diencephalon and rhombencephalon), or two (telencephalon and mesencephalon-diencephalon plus rhombencephalon) parts were examined for their biochemical differentiation by measuring the specific activities of choline acetyltransferase, acetylcholinesterase, glutamic acid decarboxylase, tyrosine 3-monooxygenase, aromatic L-amino acid decarboxylase, catechol methyltransferase and monoamine oxidase. The results showed that such parts yielded cultures that were relatively enriched for acetylcholine-synthesizing (telencephalon) or catecholamine-synthesizing (mesencephalon-diencephalon and mesencephalon-diencephalon plus rhombencephalon) enzymes. For cultures which were derived from two brain divisions, the sum of the total activity for each enzyme in the parts after 30 days equalled that in whole brain cultures derived from the same group of embryos, suggesting that development of these enzymes was unaffected by division of the brain in two. In experiments to determine the effects of culture conditions on this development, chronic administration of certain drugs was found to selectively influence the specific activity of certain neurotransmitter metabolizing enzymes. Thus, in cultures of whole brain, ascorbic acid (0.2 mM) decreased tyrosine 3-monooxygenase and aromatic L-amino acid decarboxylase while other enzymes were slightly increased; and in cultures of telencephalon and mesencephalon-diencephalon plus rhombencephalon, N6, O2'-dibutyryladenosine 3',5'-cyclic phosphate (0.2 mM) decreased the specific activities of choline acetyltransferase acetylcholinesterase, glutamic acid decarboxylase and monoamine oxidase. These results demonstrate the feasibility of growing these cultures for pharmacological studies in developmental neurobiology.

Acetylcholinesterase↗
PubMed1976

Biochemical differentiation of mechanically dissociated mammalian brain in aggregating cell culture.

Mouse and rat brain cells were dissociated by a simple mechanical sieving technique and studied in culture for the formation of aggregates and the activities of choline acetyltransferase, acetylcholinesterase, glutamic acid decarboxylase, tyrosine 3-monooxygenase, aromatic L-amino acid decarboxylase, catechol methyltransferase, and monoamine oxidase. Cells from fetal and neonatal tissue formed aggregates but not cells from tissue older than two days after birth. The pattern of development of enzyme activities in these aggregates varied with the age of starting tissue. The highest levels of specific activity for the neuron-specific enzymes were found after 3-4 weeks in culture for aggregates of cells derived from relatively undeveloped brains.

Acetylcholinesterase↗