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Biomedical subjects

H Thoenen

Publications and source records attributed to H Thoenen.

At least 181 records · Page 10Linked to original sources
PubMed1982

Nerve growth factor stimulates neurite outgrowth from goldfish retinal explants: the influence of a prior lesion.

Goldfish (Carassius auratus) retinal explants, whose ganglion cells were 'primed' in vivo by an optic nerve crush at varying intervals prior to culture, were found to respond by enhanced neurite outgrowth to low (ng/ml) concentrations of nerve growth factor (NGF). This in vitro response was dose-dependent and specific for NGF. The spontaneous fiber outgrowth which normally occurs in vitro in response to optic nerve lesion without exogenous NGF in the medium could be reduced by approximately 80% with administration of NGF antiserum. These observations strongly indicate the formation of an NGF-like molecule in the goldfish retina. The magnitude and sensitivity of the NGF response was dependent on the post-crush interval, referred to as days post-axotomy (DPA). Without a prior crush there was no response unless explants remained in culture 1-2 weeks before NGF treatment. NGF elicited the greatest increase in neurite outgrowth when administered to 7 DPA explants. With increasing intervals after axotomy the response decreased until by 35 DPA none could be elicited.

Animals↗
PubMed1982

Extract from brain stimulates neurite outgrowth from fetal rat retinal explants.

Explants from rat fetal retina were placed in culture and assayed for fiber outgrowth. In contrast to results obtained with lower vertebrates, nerve growth factor (NGF) does not seem to play a role in this system: NGF is not able to stimulate fiber outgrowth and antibodies to NGF do not block the spontaneously occurring fiber outgrowth. However, an extract prepared from pig brain is able to stimulate fiber outgrowth in a dose-dependent manner. It is suggested that such an extract can be used as a source of putative neurotrophic factors exhibiting in the mammalian central nervous system (CNS) an action similar to that of NGF in the peripheral nervous system (PNS) of mammals and in the CNS of lower vertebrates like fishes and amphibia.

Animals↗
PubMed1982

Internalization of nerve growth factor by pheochromocytoma PC12 cells: absence of transfer to the nucleus.

The intracellular distribution of 125I-labeled nerve growth factor (NGF) in rat pheochromocytoma PC12 cells was studied by quantitative electron microscopic (EM) autoradiography and by subcellular fractionation. PC12 cells were grown as monolayer cultures in medium supplemented with serum in the presence of 125I-NGF. EM autoradiography showed that 125I-NGF was localized at the plasma membrane and cytoplasmic compartments but did not accumulate in the nuclear chromatin or in the nuclear membrane compartment of cells analyzed after 1 hr and 1, 2, and 8 d of incubation with 125I-NGF. 125I-NGF also was not detected in nuclear subcellular fractions prepared from cells grown in serum-supplemented medium either in suspension for 1 d or in monolayer cultures for 1 to 8 d. In contrast, and in confirmation of the results of Yankner and Shooter (Yankner, B. A., and E. M. Shooter (1979) Pro. Natl. Acad. Sci. U. S. A. 76: 1269-1273), about 60% of the cell-bound 125I-NGF was found in the nuclear pellet after cell fractionation if the cells had been kept previously in suspension for 1 d in phosphate-buffered saline supplemented with 0.2% glucose, 0.1% bovine serum albumin, and 125I-NGF. The ultrastructure of PC12 cells grown under such conditions, however, revealed signs of varying degrees of damage. Autoradiography of the nuclear pellet from these cells showed the grains to be located mainly over damaged nuclei or over cell debris between nuclei. It is concluded that NGF, after binding to specific receptors at the plasma membrane, is transferred to membrane-confined cytoplasmic compartments but does not have to be transferred further to the nuclear membrane or to the nuclear chromatin as a prerequisite for its physiological action.

Animals↗
PubMed1981

Subpopulations of cultured chick sympathetic neurones differ in their requirements for survival factors.

Peripheral autonomic and sensory neurones derived from the neural crest will survive in vitro only if the culture medium is supplemented with specific factors (for review see ref. 1). For example, the nerve growth factor (NGF), although supporting the survival of sympathetic and spinal sensory neurons, is ineffective on parasympathetic neurones, whereas medium conditioned by chick heart cells (HCM) supports the survival of all three neuronal types. We showed previously that the requirements of cultured spinal sensory ganglion neurones for survival factors changed during development, and so provided a basis for the classification of such factors. We now demonstrate that cultured post-mitotic neurones from chick paravertebral sympathetic ganglia respond differentially to NGF, HCM and medium conditioned by C6 glioma cells (GCM). Thus, there three survival factors are functionally distinct in that they support the survival in culture of discrete subpopulations of sympathetic neurones. Those subpopulations responding to HCM and NGF are shown to differ not only in their requirements for survival factors but also in their contents of the cholinergic and adrenergic marker enzymes choline acetyltransferase (ChAT) and tyrosine hydroxylase (TH).

Animals↗
PubMed1980

Immunosympathectomy: lack of evidence for a complement-mediated cytotoxic mechanism.

To determine whether the destruction of peripheral sympathetic neurons by anti-NGF-antibodies results from a complement-mediated cytotoxic action or from the deprivation of endogenous NGF or immunologically NGF-like cross-reacting molecules we investigated the time-course of the reversibility of the effect of NGF-antibodies by neutralizing doses of NGF, together with the effect of NGF-antibodies in complement-deficient mice. After administration of a single dose of 50 mg/kg of purified antibodies to newborn rats the TH level was reduced to 75% of controls after 12 h, to 48% after 24 h, 39% after 36, and 28% after 48 h. After this time no further reduction occurred and levels remained constant up to 14 days. The effect of the NGF-antibodies was reversible on addition of NGF up to 48 h after antibody administration. Although the reversibility was not complete (85% of controls) the extent of the reversibility was the same whether NGF was given 12 or 48 h after the antibodies. The incompleteness of the reversibility is reflected by the small number of degenerating neurons apparent as early as 12 h after antibody administration. Since these early degenerative effects were also seen in complement-deficient mice it is concluded that they involve a small population of neurons, sensitive to short-term NGF deprivation whereas the majority of the neurons can withstand deprivation for up to 48 h without sustaining irreversible damage.

Adrenergic Fibers↗
PubMed1980

The role of sodium influx mediated by nicotinic receptors as an initial event in trans-synaptic induction of tyrosine hydroxylase in adrenergic neurons.

1. Isolated superior cervical ganglia of the rat were incubated for 2--30 min (37 degrees C) in Krebs' solution or tissue culture medium (BGJb) containing 22Na and then washed for 30 min in ice-cold 22Na-free Krebs' solution (to clear extracellular space). The radioactivity remaining in the ganglia was taken as a measure of 22Na influx into the intracellular compartment of the ganglion. 2. Addition of cholinomimetics (100 microM nicotine or 100 microM carbachol) to the incubation led to an increase in 22Na influx. This increase reached maximal values after 10 min of incubation; it was more pronounced after incubation in Krebs' solution than in BGJb medium. 3. While chlorisondamine (3 microM) or dopamine (100 microM) greatly reduced the carbachol-induced 22Na influx, tetrodotoxin (2 microM) did not have any effect. 4. In ganglia obtained from animals treated with 6-hydroxydopamine in the early postnatal phase (resulting in an extensive destruction of peripheral sympathetic neurons) neither carbachol (100 microM) nor nicotine (100 microM) produced an increase in 22Na influx demonstrating that the intraneuronal compartment is responsible for this enhanced influx. 5. The effects of dopamine, chlorisondamine and tetrodotoxin on the carbachol-induced 22Na uptake into superior cervical ganglia are similar to their effects on carbachol-mediated induction of tyrosine hydroxylase in superior cervical ganglia kept in tissue culture (Thoenen and Otten 1977b). It is concluded that the induction of tyrosine hydroxylase via nicotinic receptors is closely linked to the enhanced sodium influx into the adrenergic neurons mediated by the same receptors.

Animals↗
PubMed1980

Sensory neurons in culture: changing requirements for survival factors during embryonic development.

The effect of nerve growth factor (NGF) and medium conditioned by glioma cells (GCM) on the survival of chicken sensory neurons in culture was investigated. Neurons were isolated from embryos 8 days (E8) to 16 days (E16) old and the proportion of surviving neurons was determined after 2 days in culture. In the absence of NGF or GCM, essentially no neurons survived at any age. In the presence of NGF, survival increased from 25% of the neurons at E8 to 40% between E10 and E12 and then decreased to background level (5%) at E16. In contrast, in the presence of GCM, survival increased continuously from 10% of the neurons at E8 to 75% at E16. At early developmental stages, the effect of NGF and GCM together was greater than the sum of their individual effects: at E8, about 80% of the neurons survived, double the number expected for a simple additive effect. Thus, a significant proportion of chicken neurons from dorsal root ganglia require both NGF and GCM for survival, and this may well include neurons from the ventro-lateral population, which do not respond to NGF alone. As neurons matured, the double requirement progressively decreased and, by E16, NGF no longer increased the number of neurons over that surviving in response to GCM alone. The facts that rat brain extracts mimicked the effect of GCM and that the potency of the brain extracts of rat in the postnatal period increased in parallel with the development of the glial cells suggest that glial cells produce a factor(s) both immunologically and functionally different from NGF which supports the survival of sensory neurons.

Age Factors↗
PubMed1979

Nerve growth factor (NGF) in the rat CNS: absence of specific retrograde axonal transport and tyrosine hydroxylase induction in locus coeruleus and substantia nigra.

Selective, highly efficient uptake of [125I]NGF by nerve terminals followed by retrograde axonal transport, and specific induction of tyrosine hydroxylase by NGF are well known phenomena in peripheral adrenergic neurons of adult rats. In the present study these parameters were used in order to detect possible interactions of NGF with central catecholaminergic neurons. No selective retrograde transport of [125I]NGF could be detected by light microscopic autoradiography from the caudate nucleus to the dopaminergic neurons in the substantia nigra or from the hippocampus to the noradrenergic nerve cells of the locus coeruleus. Biochemically, no change in tyrosine hydroxylase activity could be observed for up to 3 days after injection of either NGF, anti-NGF antibodies, or control proteins close to the nerve cell bodies in the substantia nigra or the locus coeruleus. These data suggest a fundamental difference between central and peripheral adrenergic neurons with regard to their responsiveness of NGF.

Adrenergic Fibers↗