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M V Sofroniew

Publications and source records attributed to M V Sofroniew.

At least 37 records · Page 2Linked to original sources
PubMed1997

Expression of LIM protein genes Lmo1, Lmo2, and Lmo3 in adult mouse hippocampus and other forebrain regions: differential regulation by seizure activity.

The LIM domain is a zinc-binding amino acid motif that characterizes various proteins which function in protein-protein interactions and transcriptional regulation. Expression patterns of several LIM protein genes are compatible with roles in vertebrate CNS development, but little is known about the expression, regulation, or function of LIM proteins in the mature CNS. Lmo1, Lmo2, and Lmo3 are LIM-only genes originally identified as putative oncogenes that have been implicated in the control of cell differentiation and are active during CNS development. Using in situ hybridization for mRNA and immunohistochemical detection of reporter protein expression in transgenic mice, we found that Lmo1, Lmo2, and Lmo3 show individually unique but partially overlapping patterns of expression in several regions of the adult mouse forebrain, including hippocampus, caudate putamen, medial habenula, thalamus, amygdala, olfactory bulb, hypothalamus, and cerebral cortex. In the hippocampal formation, Lmo1, Lmo2, and Lmo3 show different combinatorial patterns of expression levels in CA pyramidal and dentate granule neurons, and Lmo1 is present in topographically restricted subpopulations of astrocytes. Kainic acid-induced limbic seizures differentially regulated Lmo1, Lmo2, and Lmo3 mRNA levels in hippocampal pyramidal and granule neurons, such that Lmo1 mRNA increased, whereas Lmo2 and Lmo3 mRNAs decreased significantly, with maximal changes at 6 hr after seizure onset and return to baseline by 24 hr. These findings show that Lmo1, Lmo2, and Lmo3 continue to be expressed in the adult mammalian CNS in a cell type-specific manner, are differentially regulated by neuronal activity, and may thus be involved in cell phenotype-specific regulatory functions.

Animals↗
PubMed1997

Brain-derived neurotrophic factor, acidic and basic fibroblast growth factors, insulin-like growth factor-I, and various antioxidants do not prevent the apoptotic death of developing septal cholinergic neurons following nerve growth factor withdrawal in vitro.

The degree to which growth factors act alone or in combination to influence neuronal survival during the development of the central nervous system is not well understood. In this study, we investigated whether multiple growth factors might interact to regulate the survival of developing basal forebrain cholinergic neurons in vitro, in the rat. We have previously shown that most embryonic septal cholinergic neurons grown in sandwich cultures in serum-free, completely defined medium are dependent on nerve growth factor during a critical period of their development, such that nerve growth factor withdrawal during this period results in the protein synthesis-dependent, apoptotic death of most, but not all, of these neurons. Here we report that brain-derived neurotrophic factor, acidic and basic fibroblast growth factors, and insulin-like growth factor-I applied individually in serum-free, completely defined medium, were not able either to support the development of septal cholinergic neurons from plating at embryonic day 16, or to prevent the cell death of these neurons induced by nerve growth factor withdrawal during days 14-18 after plating. We also found that the apoptotic death of developing septal cholinergic neurons induced by nerve growth factor withdrawal was not prevented by a number of antioxidants, with the exception of a high concentration (50 mM) of ascorbic acid. However, this effect of ascorbic acid was prevented when pH was buffered, and is likely to have been mediated via a proton-induced sustained neuronal depolarization. These findings suggest that in the absence of serum and other additives, brain-derived neurotrophic factor, acidic and basic fibroblast growth factors, and insulin-like growth factor-I do not interact with nerve growth factor to regulate the survival of septal cholinergic neurons during the developmental period spanned by this in vitro model. In addition, the findings suggest that the apoptotic death of septal cholinergic neurons induced by nerve growth factor withdrawal is not mediated by oxidative stress or free radical generation.

Animals↗
PubMed1996

Delayed death of septal cholinergic neurons after excitotoxic ablation of hippocampal neurons during early postnatal development in the rat.

To investigate the role of neuron-target interactions in regulating the survival of developing septo-hippocampal cholinergic neurons, hippocampal neurons were excitotoxically ablated in early postnatal rats. Four weeks after hippocampal ablation, hippocampal levels of brain-derived neurotrophic factor and nerve growth factor (NGF) mRNA had fallen to 15% of control values, and ipsilateral septal levels of NGF protein had fallen to 45% of control values. Four weeks after hippocampal ablation, the number of immunoreactive septal cholinergic neurons had fallen to 30% of control values. The number of cholinergic neurons in the septum correlated significantly with the amount of hippocampal tissue present. Ultrastructural analysis of the septal region at 3 days after hippocampal ablation showed no evidence of excitotoxic damage, but at 7 or 10 days showed degenerative profiles compatible with the delayed cell death of large septal neurons. Two weeks of NGF administration, initiated at 4 weeks after hippocampal lesions, failed to increase the number of detectable cholinergic neurons in the septal region, suggesting that the loss of immunoreactive neurons seen at 4 weeks represented cell death rather than downregulation of cholinergic markers. These findings suggest that septal cholinergic neurons depend for survival during early postnatal development on interactions with hippocampal neurons and are compatible with the possibility that neurotrophins play a role these interactions.

Animals↗
PubMed1996

Nerve growth factor withdrawal induces the apoptotic death of developing septal cholinergic neurons in vitro: protection by cyclic AMP analogue and high potassium.

Nerve growth factor regulates the developmental programmed cell death of certain neurons in the peripheral nervous system. The functions of nerve growth factor in the central nervous system are less well characterized. Nerve growth factor withdrawal results in the protein synthesis-dependent death of a large percentage of developing septal cholinergic neurons in sandwich tissue culture. In this study double labelling techniques were used to demonstrate that septal cholinergic neurons subjected to nerve growth factor withdrawal exhibit condensed chromatin and fragmented nuclei, and are labelled intensely for fragmented DNA. These degenerative changes are characteristic of apoptotic cell death. Half of the cholinergic neurons were committed to die and could no longer be rescued by nerve growth factor reapplication following approximately 16.5 h of nerve growth factor deprivation, whereas half of the cholinergic neurons could no longer be rescued by cycloheximide addition after only 9 h of nerve growth factor deprivation, suggesting that nerve growth factor and cycloheximide effect rescue by distinct mechanisms. Addition of a cyclic AMP analogue or depolarization with high K+, but not the general nuclease inhibitor aurintricarboxylic acid, prevented the death of cultured septal cholinergic neurons subjected to nerve growth factor withdrawal. Furthermore, these agents are capable of rescuing cholinergic neurons subjected to a period of nerve growth factor withdrawal after which addition of cycloheximide is no longer protective. Thus, nerve growth factor, cyclic AMP and high K+ can effect rescue after inhibition of translation ceases to be protective. These findings suggest that under defined conditions in vitro, withdrawal of nerve growth factor from septal cholinergic neurons during a critical period of development results in the apoptotic death of these CNS neurons, which can be prevented at the post-translational level by nerve growth factor, cyclic AMP and high K+.

Animals↗
PubMed1996

Reduced retrograde labelling with fluorescent tracer accompanies neuronal atrophy of basal forebrain cholinergic neurons in aged rats.

During ageing, basal forebrain cholinergic neurons are prone to degeneration for unknown reasons. In this study we morphometrically evaluated the retrograde labelling of basal forebrain neurons obtained after injection of FluoroGold into multiple sites in the cerebral neocortex in aged (24-33 months) as compared with young adult (four to six months) male Sprague-Dawley rats. In addition, we looked for differences in the distribution of degenerative changes in topographic subdivisions of the basal forebrain cholinergic complex of neurons identified by immunohistochemical detection of the cholinergic markers choline acetyltransferase or low-affinity neurotrophin receptor. After injection of FluoroGold into the cerebral neocortex, the number of retrogradely labelled neurons in the horizontal diagonal band/ substantia innominata and basal nucleus was significantly lower in aged rats, by 41% and 48%, respectively. In aged rats injected with FluoroGold as well as in non-injected aged rats, the numbers of neurons immunoreactive for choline acetyltransferase and low-affinity neurotrophin receptor were significantly lower, by 23-27% in the basal forebrain system as a whole, with no significant difference in the degree of decline amongst different subdivisions (i.e. medial septum, diagonal band, substantia innominata and basal nucleus). The ratios of the number of neurons labelled with FluoroGold as compared with the number of neurons immunoreactive for either cholinergic marker were significantly lower in aged rats, by 32-37%, indicating that the decline in the number of neurons retrogradely transporting tracer was greater than the decline in the number of immunoreactive neurons in aged animals. Immunoreactive as well as retrogradely labelled neurons showed a significant shrinkage of cell surface area of 6-13% in different subdivisions of the basal forebrain cholinergic system in aged rats. These findings confirm significant loss and atrophy of basal forebrain cholinergic neurons in aged rats, and demonstrate significantly reduced retrograde labelling of these neurons with fluorescent tracer applied to their target cortex. This reduced retrograde labelling suggests an impairment of either uptake or retrograde transport mechanisms in these neurons in aged rats. Such an impairment may contribute to the degenerative changes of basal forebrain cholinergic neurons observed in ageing and age-related degenerative conditions such as Alzheimer's disease.

Acetylcholine↗
PubMed1996

Increased vulnerability of septal cholinergic neurons to partial loss of target neurons in aged rats.

To investigate whether the ageing process might affect neuron-target interactions which influence the phenotype of septal cholinergic neurons, we compared the response of these neurons to partial loss of target tissue in young adult and aged animals. Groups of young adult (four to six months) or aged (24-33 months) male Sprague-Dawley rats received unilateral infusions into the hippocampus of either the excitotoxic amino acid N-methyl-D-aspartate, or vehicle. The resulting excitotoxic lesions reduced the mean cross-sectional area of the hippocampus by 55-60%. Ipsilateral septal cholinergic neurons immunohistochemically stained for either choline acetyltransferase or low-affinity neurotrophin receptor (p75NTR) were morphometrically evaluated. In young adult rats with partial hippocampal lesions, the number and staining intensity of ipsilateral septal cholinergic neurons were not significantly different from age-matched control values, but these cholinergic neurons exhibited a significant 12% reduction in cross-sectional area. In aged rats with hippocampal lesions of equivalent size, ipsilateral cholinergic neurons showed a significant 29% reduction in cross-sectional area, a significant 19% reduction in choline acetyltransferase staining intensity as measured by densitometry, and a significant 21% reduction in the number of choline acetyltransferase- but not p75NTR-stained septal neurons, as compared with age-matched control animals. These findings show that in aged rats, septal cholinergic neurons atrophy more severely in response to the partial loss of their target neurons than in young adult rats, in the form of pronounced cell shrinkage and down-regulation of intracellular levels of the transmitter-synthesizing enzyme, choline acetyltransferase, in some cases to the point of the absence of detectable staining for this marker in some cells. The continued detection of p75NTR indicates that significant neuronal cell death did not take place. These findings suggest that basal forebrain cholinergic neurons have an increased vulnerability to disturbances of neuron-target interactions in aged animals, which may contribute to the degenerative changes exhibited by these cholinergic neurons in ageing and age-related conditions such as Alzheimer's disease.

Acetylcholine↗
PubMed1996

Do central nervous system neurons require target-derived neurotrophic support for survival throughout adult life and aging?

Many growth factors that have effects on neurons are present in the developing and mature central nervous system where their functions are poorly understood. In the peripheral nervous system, target-derived growth factors can regulate the survival of developing afferent neurons. Recent studies suggest that neurotrophins derived from target neurons may also regulate the survival of afferent basal forebrain cholinergic neurons during development of the central nervous system. However, in mature animals, these cholinergic neurons do not appear to require target-derived neuroptrophins for survival. Similar findings have also been reported for dopaminergic neurons of the substantia nigra. Although further studies are required, available experimental evidence suggests that target-derived growth factors may influence neuronal phenotypes such as axonal sprouting or transmitter production instead of survival in mature animals.

Aging↗
PubMed1995

Ciliary neurotrophic factor supports p75NGFR-immunoreactive non-cholinergic, but not cholinergic, developing septal neurons in vitro.

Ciliary neurotrophic factor is known to exert both survival and differentiative actions on a number of neuronal populations of the peripheral and central nervous systems. In this study we have compared the trophic effects of ciliary neurotrophic factor and nerve growth factor on developing septal neurons of the rat in vitro. Fetal septal neurons were grown in vitro under glass coverslips in sandwich culture. Septal cultures grown for 14 days in the continual presence of nerve growth factor contain a population of cholinergic neurons that stain intensely for the low-affinity nerve growth factor receptor (p75NGFR), choline acetyltransferase and acetylcholinesterase. Without added nerve growth factor, few neurons stain for these markers. Ciliary neurotrophic factor addition for 14 days from plating in the absence of exogenous nerve growth factor results in the appearance of a population of neurons that stains for p75NGFR. This population is similar in number to that seen in nerve growth factor-treated cultures but is not immunoreactive for choline acetyltransferase and is significantly smaller in mean cross-sectional area. Delayed addition of nerve growth factor to ciliary neurotrophic factor-supported cultures at 14 days for a further seven days fails to induce choline acetyltransferase immunoreactivity in these p75NGFR-positive septal neurons. In cultures grown in the continual presence of nerve growth factor from plating, removal of nerve growth factor and addition of nerve growth factor antibodies at 14 days results in the death of over 80% of the cholinergic neurons after a further four days. Addition of ciliary neurotrophic factor during the period of nerve growth factor withdrawal appears to preserve a p75NGFR-positive, choline acetyltransferase-negative neuronal population. However, seven day re-addition of nerve growth factor to ciliary neurotrophic factor-treated, nerve growth factor-withdrawn cultures fails to induce choline acetyltransferase immunoreactivity in the ciliary neurotrophic factor-supported p75NGFR-positive septal neurons. Simultaneous treatment of cultures with both ciliary neurotrophic factor and nerve growth factor for 14 days from plating approximately doubles the number of p75NGFR-positive neurons relative to cultures treated with either ciliary neurotrophic factor or nerve growth factor alone, but the number of choline acetyltransferase-positive neurons in these cultures is not significantly greater than that found in cultures treated solely with nerve growth factor. These results suggest that ciliary neurotrophic factor does not support the survival and differentiation of developing septal cholinergic neurons in vitro, but can support the development of a p75NGFR-immunoreactive population of non-cholinergic septal neurons.

Animals↗
PubMed1995

The Hox11 gene is essential for cell survival during spleen development.

The HOX11 homeobox gene was identified via the translocation t(10;14) in T cell leukaemia. To determine the function of this gene in mice, null mutations were made using homologous recombination in ES cells to incorporate lacZ into the hox11 transcription unit. Production of beta-galactosidase from the recombinant hox11 allele in +/- mutants allowed identification of sites of hox11 expression which included the developing spleen. Newborn hox11 -/- mice exhibit asplenia. Spleen formation commences normally at E11.5 in hox11 -/- mutant embryos but the spleen anlage undergoes rapid and complete resorption between E12.5 and E13.5. Dying spleen cells exhibit molecular features of apoptosis, suggesting that programmed cell death is initiated at this stage of organ development in the absence of hox11 protein. Thus hox11 is not required to initiate spleen development but is essential for the survival of splenic precursors during organogenesis. This function for hox11 suggests that enhanced cell survival may result from the t(10;14) which activates HOX11 in T cell leukaemias, further strengthening the association between oncogene-induced cell survival and tumorigenesis.

Animals↗
PubMed1995

Attempted modulation of herpes simplex virus (HSV) infection of neurons in culture by fibroblast growth factor.

It has been suggested that fibroblast growth factor (FGF) receptors may mediate entry of herpes simplex virus (HSV) to susceptible cells. We investigated the possible modulation of acute lytic HSV infection of cultured rat neurons by basic FGF, using cell-specific markers and indirect immunostaining. Dissociated neural cell cultures were prepared from the medial septal region of the basal forebrain, the hippocampus and dorsal root ganglion (DRG). The proportion of neurons in the cultures was enhanced by the addition of cytosine arabinoside (2 microM) in the hippocampal and DRG cultures and by inversion of the coverslips in septal cultures. The percentage of MAP2+ and neurofilament+ neurons in these cultures varied between 9 and 95%. Cultures were treated with basic FGF (4-5 ng ml-1) continuously and infected with wild-type HSV-1, untreated uninfected cultures acting as controls. Both FGF binding and FGF receptors were demonstrated in hippocampal, and to a much lesser extent, DRG neurons. In repeated experiments it was found that FGF treatment did not have a significant effect on lytic infection in any of the neuronal populations studied as assessed by the development of viral antigen expression and comparison of identified neurons in FGF, treated versus untreated, infected cultures. Our data show that FGF does not have a 'neuroprotective' effect on HSV infection of either central or peripheral neurons.

Animals↗
PubMed1994

Changes in CCK mRNA in hippocampal neurones following fimbria fornix transection.

Preprocholecystokinin (CCK) mRNA expression was measured in a subset of hippocampal interneurones after transection of afferent septohippocampal fibres in the fimbria fornix. Two weeks after the lesions were made, CCK mRNA levels were significantly lower in these neurones on the side ipsilateral to the lesion compared with equivalent neurones on the unlesioned side. These findings suggest that axotomizing lesions can change gene expression in denervated target cells, and that CCK mRNA levels in hippocampal interneurones may be modulated by afferent septohippocampal input.

Afferent Pathways↗
PubMed1994

NMDA potentiates NGF-induced sprouting of septal cholinergic fibres.

Nerve growth factor (NGF) injected into the otherwise unlesioned adult rat septum induced sprouting of presumptive cholinergic fibres positive for p75NGFR and acetylcholinesterase (AChE). These fibres did not stain for tyrosine hydroxylase and therefore did not represent sympathetic ingrowth. Neurofilament staining on adjacent sections revealed fibres with similar morphology, suggesting new outgrowth in the form of sprouting rather than the upregulation of p75NGFR and AChE in pre-existing fibres. Simultaneous injections of subneurotoxic doses of N-methyl-D-aspartate (NMDA) significantly potentiated the effect of NGF on cholinergic fibre sprouting and caused pronounced glial fibrillary acidic protein (GFAP)-positive astrocytosis. Application of NMDA alone did not elicit sprouting of this type. These findings indicate that NGF can induce the sprouting of uninjured adult rat septal cholinergic fibres in vivo and suggest that reactive astrocytes are not inhibitory to cholinergic axonal outgrowth, and might serve as a substrate for growing axons in the presence of NGF.

Acetylcholine↗
PubMed1994

Reduced transport of [125I]nerve growth factor by cholinergic neurons and down-regulated TrkA expression in the medial septum of aged rats.

Basal forebrain cholinergic neurons atrophy and degenerate in aging and Alzheimer's disease for unknown reasons. In this study, aged male Sprague-Dawley rats (26-30 months old) showed a significant 31% reduction in the number of septal cholinergic neurons which take up and retrogradely transport 125I-labelled nerve growth factor injected into their target hippocampus, as compared with young adult rats (three to six months old). In aged rats, cholinergic neurons not transporting nerve growth factor were severely atrophied and had a significant 60% reduction in mean cross-sectional area as compared with [125I]nerve growth factor transporting neurons. These changes were accompanied by a significant 43% decline in relative levels of messenger RNA encoding the high affinity nerve growth factor receptor TrkA, in the septal region of aged rats. There was no difference between young and aged rats in messenger RNA levels encoding the low affinity nerve growth factor receptor, p75NGFR. These findings suggest that aged basal forebrain cholinergic neurons exhibit a reduced capacity to sustain receptor mediated uptake and retrograde transport of target-derived neurotrophin. This reduced capacity is associated with severe neuronal atrophy and may contribute to the pronounced vulnerability of these neurons to degeneration in aging and Alzheimer's disease.

Aging↗
PubMed1994

Death of developing septal cholinergic neurons following NGF withdrawal in vitro: protection by protein synthesis inhibition.

Fetal septal neurons were grown in vitro under glass coverslips. This sandwich culture method significantly increased general neuronal survival, reduced glial proliferation, and permitted the removal of serum from the growth medium after 5 d in vitro. Thereafter, a simple, and completely defined, medium was used, and the effects of NGF, NGF withdrawal, and protein synthesis inhibition were examined on septal cholinergic neurons. NGF added to septal cultures at the time of plating resulted in a threefold increase in the number of cholinergic neurons seen at 14 d in vitro but had no effect on the survival of non-cholinergic cells. Cholinergic neurons identified by staining for AChE, ChAT, and p75NGFR could be maintained in serum-free, NGF-supplemented medium for over 40 d. When NGF was removed and NGF antibodies added to 14-d-old cultures, less than 30% of cholinergic neurons survived a further 4 d, but when NGF was similarly withdrawn from 35-d-old cultures, over 75% of cholinergic neurons survived. Reapplication of NGF after 3 but not after 12 or more hours of NGF withdrawal from 14-d-old cultures prevented the death of most cholinergic neurons. When NGF was withdrawn from 14-d-old cultures in the presence of the protein synthesis inhibitor cycloheximide, over 75% of the cholinergic neurons survived. These findings suggest that septal cholinergic neurons are dependent on NGF for survival only during a critical period of development and that growth factor-regulated developmental cell death may occur in CNS neurons by activation of programmed cell death requiring protein synthesis.

Animals↗
PubMed1994

Transfection with hsp70i protects rat dorsal root ganglia neurones and glia from heat stress.

Studies have shown that the induction of heat shock proteins (hsp's) in the CNS is protective against excitotoxicity and correlative evidence also suggest that hsp's may be protective against ischemic stress and free radical damage. In fibroblasts and Chinese hamster ovary cells expression of hsp70i has been shown to be essential if the cells are to survive an heat stress. To investigate the effect of constitutive overexpression of hsp72 inducible (hsp70i) in neurones and glia we transfected rat dorsal root ganglia (DRG) with a plasmid construct containing the human EF-1 alpha-promoter and human hsp70i. The results showed that prior transfection with hsp70i protected both neurones and glia from heat stress. These data support the hypothesis that overexpression of hsp70i plays an important role in enhancing the survival of neuronal cells following stress and suggests that the induction of a stress response in the CNS may provide an alternative form of treatment for neurodegenerative diseases.

Animals↗
PubMed1993

Transfection-mediated expression of human Hsp70i protects rat dorsal root ganglian neurones and glia from severe heat stress.

Considerable evidence suggests that the expression of heat shock proteins prior to a toxic insult (e.g. ischaemia, excitoxins, heat) can confer protection to neurones and glia. It is not certain which hsp(s) are involved in conveying these neuroprotective effects. Here we show that calcium phosphate-mediated transfection of dorsal root ganglia with an EF-1 alpha promoter-hsp70i expression vector significantly increased the survival of neurones and glia exposed to a severe heat stress. These data suggest that overexpression of hsp70i plays an important role in protecting neurones and glia from the denaturing effects of severe thermal stress. Inducing the expression of specific hsps may lead to the development of novel treatment strategies for CNS diseases.

Animals↗