Choline acetyltransferase and acetylcholinesterase in cultured brain cells from chick embryos

Parallel development of acetylcholinesterase in vivo and in primary neuron surface culture

The development of acetylcholinesterase (AChE) activity in primary surface cultures of mouse cortical neurons and in mouse brain was examined. The specific activity of AChE in culture increased over 600% during a 3 week period and closely paralleled the development of AChE observed in vivo. The results obtained in this study show that a developmental increase in AChE can be obtained in primary surface neuron cultures, and that the high degree of cellular organization previously deemed necessary for this development in vitro is not as important as previously thought.

The effect of cyclic AMP on neuritic outgrowth in explant cultures of developing chick olfactory epithelium

The effect of cyclic AMP (cAMP) analogs and phosphodiesterase (PDE) inhibitors on neurite outgrowth was studied in explant cultures of olfactory neurons. Nasal pits from 5- or 6-day-old chick embryos were minced, explanted into culture dishes, and grown in a serum-free medium. One of the cyclic AMP analogs, dibutyryl cyclic AMP (dbcAMP) or 8-bromo-cyclic AMP (8-Br-cAMP), or one of the PDE inhibitors, theophylline or isobutylmethylxanthine (IBMX), was added to the culture medium. The explants were examined for neurite outgrowth after 2 days in vitro. Db-cAMP increased the number of explants expressing neurites by 25-35% over control cultures, whereas 8-Br-cAMP had essentially no effect at the same concentrations. Addition of dibutyryl cyclic GMP (dbcGMP) gave no increase in neurite outgrowth, thus indicating that the effect of enhancing neuritic growth is specific to cAMP and not cyclic nucleotides in general. The resulting increase in neurite outgrowth is due to the cyclic nucleotide component of dbcAMP, since both IBMX and theophylline, which elevate intracellular cAMP, also increased neurite outgrowth significantly. When forskolin was added to the culture medium, there was a trend to increased neurite outgrowth; this was significantly enhanced when a subthreshold concentration of theophylline was added in addition to the forskolin.

Cell and tissue culture of the central nervous system: recent developments and current applications

A survey of methods for cell and tissue culture of the central nervous system (CNS) is given. This includes a brief historical outline and description of methods in current use. Recent methodological improvements are emphasized, and it is shown how these are applied in modern neurobiological research. Both monolayer cell cultures and three-dimensional organ culture systems are widely used, each having advantages and limitations. In recent years, there has been considerable improvement of culture for prolonged periods in chemically defined media. Brain tissue from a wide spectrum of species have been used, including different types of human brain cells which can be propagated for several months. At present, these culture systems are employed for dynamic studies of the developing, the adult and ageing brain. It is possible to select neurons and the different classes of glial cells for culture purposes. Cell culture of the CNS has given new insights into the biology of brain tumours. Culture systems for experimental tumour therapy in vitro are also available. Recently, it has been shown that organ cultures of brain tissue can be used as targets for invasive glioma cells, enabling a direct study of the interactions between tumour cells and normal tissue to take place.

Development of cholinergic properties in nerve cell cultures in the presence of brain extract

Cells dissociated from cerebral hemispheres of 6-day-old chick embryos were cultured either in standard nutrient medium or in the presence of a brain extract from 8-day-old chick embryo. Morphological observations showed the development of bipolar and multipolar neurons in both culture conditions and acetylcholinesterase activity was found in all neuronal cells. Brain extract stimulated the morphological maturation of neurons, expressed by the formation of fiber bundles, fine structural maturation and development of synapses rich in clear vesicles. Furthermore, acetylcholinesterase and choline acetyltransferase activities were higher in the cultures treated with brain extract. In these cultures, the values of choline acetyltransferase activity reached a peak at 10 days and then decreased. These observations are discussed with particular reference to proliferation, maturation and degeneration of cholinergic neurons.

Induction of cholinergic expression in developing spinal cord cultures

The induction of choline acetyltransferase (ChAT) by cAMP derivatives was studied in dissociated spinal cord cultures. Dibutyryl cAMP (dbcAMP) and 8-bromo cAMP (1 mM) produced a 2-3-fold stimulation of ChAT activity in developing cultures whereas 8-bromo cGMP had no effect. A phosphodiesterase inhibitor, 3-isobutyl-l-methylxanthine, also increased (2-fold) ChAT activity in immature cultures. Significant elevations in ChAT were detected after 2 h incubation with dbcAMP. Maximum enzyme induction was observed 24 h after dbcAMP supplementation to the culture medium. Developmental studies revealed that ChAT could be induced on days 2-16 in culture. The largest induction of ChAT activity was observed on day 7 in culture. After day 19, when control enzyme activity attained levels of mature cultures, cAMP-mediated ChAT induction was no longer observed. Cycloheximide and actinomycin D blocked ChAT induction whereas basal enzyme activity remained unaffected. Culture protein content was not changed after 1-day exposure to dbcAMP. 125I-Tetanus toxin fixation after dbcAMP treatment revealed a 20% decrease from control in neuronal surface during days 7-9 in culture. These data indicated that cAMP derivatives produced a rapid increase in cholinergic expression during a specific period of development in spinal cord cultures. There appears to be specificity to this effect, as total neuronal surface does not respond in the same manner as ChAT activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase changes in the central nervous system of mice during the development of morphine tolerance addiction and withdrawal

The distribution of acetylcholinesterase in the brain is studied during the development of morphine tolerance and through a period of withdrawal to elucidate the possible role of this enzyme in producing physical dependence in mice. Tolerance and physical dependence are produced in male albino mice by giving morphine sulphate subcutaneously at eight hourly intervals, in an increasing dose of 10 mg/kg body weight every 24 hours, for 15 days. The animals are considered addicted, when they received an otherwise lethal dose, 150 mg/kg three times a day. The enzyme shows a marked elevation in the overall distribution during the development of physical dependence. The habenular complex, nuclei anterioventralis and medialis thalami, nucleus caudatus putamen, amygdaloideus lateralis, septal nuclei, nucleus nervi hypoglossi, nucleus reticularis lateralis, tuberculum olfactorium, nucleus tractus diagonalis brocae, stratum pyramidale hippocampi, nucleus paraventricularis thalami, nucleus dorsalis nervi vagi, nucleus tractus spinalis nervi trigemini and nucleus reticularis thalami show an increase in the enzyme activity. This enhancement is not linear with the increase in dosage. Withdrawal is characterised by a sudden fall in the activity of acetylcholinesterase in the above mentioned areas of brain.

Opiates, endorphins and the developing organism: a comprehensive bibliography

A comprehensive bibliography of the literature concerned with opiates, endorphins, and the developing organism is presented. A total of 1378 clinical and laboratory references, with citations beginning in 1875, are recorded. A series of indexed accompanies the citations in order to make the literature more accessible. These indexes are divided into clinical and laboratory topics. The clinical section is subdivided into: age of subject examined; maternal aspects; effects on the fetus; pharmacology, physiology, and the withdrawal syndrome; and "other" effects on the offspring. The laboratory section is subdivided into: type of opiate/endorphin studied; species utilized; and major subject areas explored.

A comparative study of the differentiation of dissociated nerve cells under different culture conditions

In vitro differentiation of chick embryo brain cells was compared under several culture conditions. Morphological observations and acetylcholinesterase histochemical staining revealed that the development was similar in all conditions tested if cells have been derived from 7 days embryos. Considering the cultures from 11 days embryos, the cell dissociation by trypsin and the plastic surface proved to be the most favourable conditions in contrast to mechanical dissection and collagen surface.

The fine localization of ATPases in cultures in vitro of chick embryo spinal cord

A histochemical study of the ultrastructural localization of ATPases in cultures of chick embryo spinal cord has been carried out. The localization of Ca2+ and Mg2+ activated membrane ATPases appears similar: both enzyme activities are localized on the outer surfaces of plasma membranes of all kinds of cell present in the cultures, with the exception of the membranes in direct contact with the culture medium. The results are discussed in relation to data concerning the localization and function of ATPases in vivo and in relation to the possible establishment of mechanisms of nutrient uptake and transfer in cultures of nervous tissue.

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.

Neurons from fetal rat brain in a new cell culture system: a multidisciplinary analysis

A new culture system for cells from the mammalian brain was developed by a modification of a previously established technique. This modification involved the use of fluorodeoxyuridine and adult horse serum. The cultures contained large, easily visualized neurons both isolated from other neurons and in networks of varying complexity. These cells were large enough to permit reliable intracellular electrophysiologic recording and were often sufficiently dispersed to allow examination of membrane responses to iontophoretically applied neurotransmitter candidates. Many responses characteristic of central neurons in situ were seen, including evoked and spontaneous action potentials, complex patterns of inhibitory and excitatory post-synaptic potentials, and neurotransmitter-induced membrane responses. These preparations were examined by phase contrast microscopy, by light microscopy after silver impregnation and by Nomarski interference optics. Total choline acetyltransferase (CAT) activity was little changed and specific activity was increased in the new culture system as compared with the earilier system. Conditions which gave the highest specific activity of CAT also provided the best cultures from the standpoint of electrophysiologic and morphologic analysis. This new approach will allow, in culture, detailed multidisciplinary analyses of individual neurons and small networks of neurons from the mammalian brain.

The influence of non-neuronal cells on catecholamine and acetylcholine synthesis and accumulation in cultures of dissociated sympathetic neurons

The effects of several non-neuronal cell types on neurotransmitter synthesis in cultures of dissociated sympathetic neurons from the new-born rat were studied. Acetylcholine synthesis from radioactive choline was increased 100- to 1000-fold in the presence of non-neuronal cells from sympathetic ganglia. This increase was roughly dependent on the number of ganglionic non-neuronal cells present. The effect did not appear to be due to an increased plating efficiency of neurons, since the non-neuronal cells were capable of increasing acetylcholine synthesis after only 48-hr contact with neurons that had been previously grown without non-neuronal cells for 2 weeks. C6 rat glioma cells were also able to stimulate acetylcholine synthesis, but 3T3 mouse fibroblast cells had little or no effect. None of the non-neuronal cell types synthesized detectable acetylcholine in the absence of the neurons. The ganglionic non-neuronal cells had no significant effect on catecholamine synthesis (which occurs in the absence of non-neuronal cells).

The uptake of gamma-aminobutyrate by organotypic cultures of chick spinal cord

1. Explants of spinal cord from 10-day chick embryos maintained for up to 16 days in culture rapidly accumulated gamma-amino[(3)H]butyrate when incubated at 25 degrees C or 36 degrees C in a medium containing 50nm-gamma-aminobutyrate. The mechanism of the uptake process has many of the properties of an active-transport system: it is Na(+)-dependent, temperature-sensitive, inhibited by ouabain, and displays saturation kinetics. The apparent K(m) for gamma-aminobutyrate is 1.7x10(-5)m, and V(max.) is 33pmol/min per g. 2. The rate of accumulation of gamma-amino[(3)H]butyrate in cultures between the ages of 3 and 16 days was remarkably constant and was not related to the morphological maturity of the spinal-cord explants. 3. The present demonstration in spinal-cord explants of an active transport system for gamma-aminobutyrate, already established for non-cultured nervous tissue, means that nervous-tissue culture can provide a convenient model for studying uptake processes in the central nervous system.

Neurotrophic effect on isolated chick embryo muscle in culture

Acetylcholinesterase activity in cultures of dissociated skeletal muscle prepared from the thigh muscle of the 10-day-old chick embryo was increased by the presence of innervating spinal cord explants, spinal cord explants in a parabiotic environment, and by media containing brain-spinal cord extract.