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K Unsicker

Publications and source records attributed to K Unsicker.

At least 73 records · Page 4Linked to original sources
PubMed1998

TGF-beta regulates the survival of ciliary ganglionic neurons synergistically with ciliary neurotrophic factor and neurotrophins.

We investigated putative roles of transforming growth factor (TGF)-beta expressed in peripheral ganglia in the regulation of neuronal cell survival during the period of ontogenetic neuron death (OD). The chick ciliary ganglion (CG), where OD occurs between embryonic days (E) 6 and 10, was employed as a model system. We show that CG neurons (E8) are immunoreactive (ir) for TGF-beta2 and -beta3 as well as the TGF-beta receptor TbetaR-II, but are not ir for TGF-beta1. Ciliary neurotrophic factor (CNTF) and fibroblast growth factor (FGF)-2, established neurotrophic molecules for CG neurons, up-regulate TGF-beta3 mRNA and TGF-beta biological activity in cultures of E8 CG neurons. None of the TGF-beta isoforms--beta1, beta2, or beta3--has a trophic, survival-promoting effect on cultured CG neurons. However, all isoforms enhance CG neuron survival mediated by CNTF or FGF-2, significantly and over a wide range of concentrations. In combination with the neurotrophins (NT) nerve growth factor (NGF) and NT-3, which are not neurotrophic for CG neurons, TGF-beta significantly promotes CG neuron survival. However, TGF-beta does not act synergistically with the neuropoietic cytokines oncostatin M, leukemia inhibiting factor, or interleukin-6. Immunoneutralization of endogenous TGF-beta released from CG neurons using an antibody to TGF-beta1/-beta2/-beta3 significantly reduces the potency of CNTF or FGF-2 to promote CG neuron survival. The blocking effect of the anti-pan-TGF-beta antibody could be rescued by adding exogenous TGF-beta. Together, these data suggest that para-/autocrine TGF-beta signaling has an important effect on the regulation of neuron survival in a model system of peripheral neurons.

Animals↗
PubMed1997

GDNF induces the calretinin phenotype in cultures of embryonic striatal neurons.

Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor-beta (TGF-beta) superfamily, is a potent neurotrophic factor for several neuron populations in the central and peripheral nervous system. Members of the neurotrophin, neurokine, and TGF-beta families of growth factors can affect neurons beyond their capacity to promote survival. They can play instructive roles including the determination of a particular transmitter phenotype. Here, we show that GDNF enhances the number of calretinin (CaR)-positive neurons in serum-free cultures of striatal cells isolated from embryonic rats. The effect is dose-dependent, can be elicited with concentrations as low as 0.1 ng/ml, and is not accompanied by increased incorporation of 5-bromo-2'-desoxyuridine and appearance of glial fibrillary acidic protein-positive cells. Similar, but weaker effects can be elicited by brain-derived neurotrophic factor, neurotrophin-3 and -4, fibroblast growth factor-2. Ciliary neurotrophic factor, nerve growth factor, and TGF-beta 1 do not affect striatal CaR expression. GDNF can augment CaR-positive cells at any time point and with a minimal exposure of 18 hr, suggesting induction of the phenotype rather than increased survival. By reverse transcription polymerase chain reaction (RT-PCR), we show that GDNF is expressed in the E16 striatum and in cultures derived from this tissue. GDNF also protected striatal CaR-positive neurons against glutamate toxicity. We conclude that striatal GDNF, in addition to its retrograde trophic role for nigrostriatal dopaminergic neurons, may also act locally within the striatum (e.g., by inducing the CaR phenotype and protecting these cells against toxic insult).

Animals↗
PubMed1997

Characterization of growth/differentiation factor 5 (GDF-5) as a neurotrophic factor for cultured neurons from chicken dorsal root ganglia.

Growth/differentiation factor-5 (GDF-5), a morphogenetic protein, has previously been shown to act as a neurotrophic factor for midbrain dopaminergic neurons. To further elucidate the neurotrophic potential of GDF-5, serum free cultures of dorsal root ganglionic (DRG) neurons from developing chick embryos were treated with GDF-5 with or without the simultaneous addition of other trophic factors. Our results show that GDF-5 has a minor promoting effect on its own, but it can enhance the survival promoting effect of neurotrophin-3 (NT-3) and nerve growth factor (NGF) on cultured DRG neurons. Our finding fits well into the concept that neurotrophic factors may act synergistically in ensuring survival of different neuronal populations. The capacity of GDF-5 to reduce the requirement of a subpopulation of sensory neurons for NT-3 may have implications for the treatment of peripheral neuropathies.

Animals↗
PubMed1997

Protein from chromaffin granules promotes survival of mesencephalic dopaminergic neurons by an EGF-receptor ligand-mediated mechanism.

Chromaffin cells grafted to the brain of animals with experimental parkinsonism and patients with Parkinson's disease can restore nigrostriatal functions. Mechanisms underlying these beneficial effects are unknown, but may include growth factors rather than the minute amounts of dopamine (DA) liberated from chromaffin cells. We now report that protein from chromaffin granules, which release their contents by exocytosis, promotes survival and uptake of 3H-DA of mesencephalic DAergic neurons in vitro and protect against N-methylpyridinium ion toxicity. This neurotrophic effect is accompanied by cell proliferation and mediated by astroglial cells induced in these cultures. Inhibition of cell proliferation and concomitant astrogliosis by 5-fluorodeoxyuridine and alpha-aminoadipic acid abolishes the trophic effect. Two highly specific inhibitors of the epidermal growth factor receptor (EGFR) signal transduction pathway, 4,5-dianilinophthalimide (10 microM) and tyrphostin B56 (10 microM), selectively block the neurotrophic capacity of chromaffin granule protein. As expected, they also block the mitogenic effects of EGF and TGF-alpha. However, these two mitogens do not mimic the pronounced mitogenic and trophic actions of chromaffin granule protein. Culture medium conditioned by mesencephalic cells pretreated with chromaffin granule protein promotes survival of DAergic neurons without increasing numbers of astroglial cells. The effective molecule is unlikely to be glial cell line-derived neurotrophic factor, whose mRNA is not detectable in cultures treated with chromaffin granule protein. We conclude that chromaffin granules contain a putatively novel growth factor, which signals through the EGFR and may be responsible for the known protective and restorative actions of chromaffin cell grafts to the lesioned nigrostriatal system.

1-Methyl-4-phenylpyridinium↗
PubMed1997

Reduced acetylcholinesterase (AChE) activity in adrenal medulla and loss of sympathetic preganglionic neurons in TrkA-deficient, but not TrkB-deficient, mice.

TrkA high-affinity receptors are essential for the normal development of sympathetic paravertebral neurons and subpopulations of sensory neurons. Paravertebral sympathetic neurons and chromaffin cells of the adrenal medulla share an ontogenetic origin, responsiveness to NGF, and expression of TrkA. Which aspects of development of the adrenal medulla might be regulated via TrkA are unknown. In the present study we demonstrate that mice deficient for TrkA, but not the neurotrophin receptor TrkB, show an early postnatal progressive reduction of acetylcholinesterase (AChE) enzymatic activity in the adrenal medulla and in preganglionic sympathetic neurons within the thoracic spinal cord, which are also significantly reduced in number. Quantitative determinations of specific AChE activity revealed a massive decrease (-62%) in the adrenal gland and a lesser, but still pronounced, reduction in the thoracic spinal cord (-40%). Other markers of the adrenal medulla and its innervation, including various neuropeptides, chromogranin B, secretogranin II, amine transporters, the catecholamine-synthesizing enzymes tyrosine hydroxylase and PNMT, synaptophysin, and L1, essentially were unchanged. Interestingly, AChE immunoreactivity appeared unaltered, too. Preganglionic sympathetic neurons, in contrast to adrenal medullary cells, do not express TrkA. They must, therefore, be affected indirectly by the TrkA knock-out, possibly via a retrograde signal from chromaffin cells. Our results suggest that signaling via TrkA, but not TrkB, may be involved in the postnatal regulation of AChE activity in the adrenal medulla and its preganglionic nerves.

Acetylcholinesterase↗
PubMed1997

Generation of cell diversity in the peripheral autonomic nervous system: the sympathoadrenal cell lineage revisited.

Based on recent evidence from in vitro and gene knock-out/knock-in studies this short review summarizes the molecular scenario underlying the development of autonomic neurons from the neural crest. The focus is on the sympathoadrenal (SA) cell lineage. While migrating ventrally precursors of this cell lineage are exposed to signals from notochord/ventral neural tube probably including the protein sonic hedgehog. These and signals in the region of the dorsal aorta (members of the family of bone morphogenetic proteins), where SA progenitor cells subsequently assemble, are essential for the induction of the adrenergic phenotype. SA progenitor cells subsequently differentiate into paravertebral and prevertebral sympathetic neurons, intra- and extra-adrenal chromaffin cells and intermediate SIF (small intensely fluorescent) cells. Based on in vitro studies with isolated SA and chromaffin progenitor cells glucocorticoids have been claimed as essential for suppressing a neuronal commitment and channeling SA cells towards the chromaffin phenotype. Unexpectedly, mice deficient for a functional glucocorticoid receptor possess the full complement of adrenal chromaffin cells at birth. We present a hypothetical scenario consistent with these data, in which chromaffin cell development would be the default pathway in the SA cell lineage, while development into a neuronal direction requires specific growth factor signaling, which is probably distinct for paravertebral and prevertebral sympathetic neurons.

Animals↗
PubMed1997

Distinct sites of intracellular production for Alzheimer's disease A beta40/42 amyloid peptides.

The Alzheimer amyloid precursor protein (APP) is cleaved by several proteases, the most studied, but still unidentified ones, are those involved in the release of a fragment of APP, the amyloidogenic beta-protein A beta. Proteolysis by gamma-secretase is the last processing step resulting in release of A beta. Cleavage occurs after residue 40 of A beta [A beta(1-40)], occasionally after residue 42 [A beta(1-42)]. Even slightly increased amounts of this A beta(1-42) might be sufficient to cause Alzheimer's disease (AD) (reviewed in ref. 1, 2). It is thus generally believed that inhibition of this enzyme could aid in prevention of AD. Unexpectedly we have identified in neurons the endoplasmic reticulum (ER) as the site for generation of A beta(1-42) and the trans-Golgi network (TGN) as the site for A beta(1-40) generation. It is interesting that intracellular generation of A beta seemed to be unique to neurons, because we found that nonneuronal cells produced significant amounts of A beta(1-40) and A beta(1-42) only at the cell surface. The specific production of the critical A beta isoform in the ER of neurons links this compartment with the generation of A beta and explains why primarily ER localized (mutant) proteins such as the presenilins could induce AD. We suggest that the earliest event taking place in AD might be the generation of A beta(1-42) in the ER.

Alzheimer Disease↗
PubMed1997

Bone morphogenetic proteins: neurotrophic roles for midbrain dopaminergic neurons and implications of astroglial cells.

Bone morphogenetic proteins (BMPs) are members of the transforming growth factor beta (TGF-beta) superfamily that have been implicated in tissue growth and remodelling. Recent evidence suggests that several BMPs are expressed in the developing and adult brain. Specifically, we show that BMP 2 and BMP 6 are expressed in the developing midbrain floor of the rat. We studied potential neurotrophic effects of BMPs on the in vitro survival, transmitter uptake and protection against MPP+ toxicity of mesencephalic dopaminergic neurons cultured from the embryonic midbrain floor at embryonic day (E) 14. At 10 ng/ml and under serum-free conditions, most BMPs promoted the survival of dopaminergic neurons visualized by tyrosine hydroxylase immunocytochemistry during an 8-day culture period, but to varying extents (relative potencies: BMP 6 = 12 > 2, 4, 7). BMPs 6 and 12 were as effective as fibroblast growth factor-2 (FGF-2) and glial cell line-derived neurotrophic factor, promoting survival 1.7-fold compared with controls. BMPs 9 and 11 were not effective. Dose-response curves revealed an EC50 for BMPs 2, 6 and 12 of 2 ng/ml. BMPs 2, 4, 6, 7, 9 and 12 also promoted DNA synthesis and astroglial cell differentiation, visualized by 5-bromodeoxyuridine (BrdU) incorporation and glial fibrillary acidic protein (GFAP) immunocytochemistry respectively. Suppression of cell proliferation and subsequent maturation of GFAP-positive cells by 5-fluorodeoxyuridine or aminoadipic acid abolished the neuron survival-promoting effect of BMP 2. This suggests that BMPs, like other non-TGF-beta factors affecting dopaminergic neuron survival, act indirectly, probably by stimulating the synthesis and/or release of glial-derived trophic factors. BMP 6 and BMP 7 also increased the uptake of [3H]dopamine without affecting the uptake of [3H]5-hydroxytryptamine and [3H]GABA, underscoring the specificity of the trophic effect. We conclude that several BMPs share a neurotrophic capacity for dopaminergic midbrain neurons with other members of the TGF-beta superfamily, but act indirectly, possibly through glial cells.

1-Methyl-4-phenylpyridinium↗
PubMed1996

Expression of neurotrophins and their receptors in the developing and adult rat adrenal gland.

We have studied the postnatal expression of neurotrophins, their cognate high-affinity trk receptors and the low-affinity NGF receptor (p75LNGFR) in the rat adrenal gland using RT-PCR. Neurotrophin mRNAs were detectable during the whole postnatal period. Strongest signals were obtained for BDNF and NT4/5. Expression of trkA, trkB, trkC and p75LNGFR was found at all ages studied. Signals for trkA were highest in the adult adrenal medulla, whereas signals for p75LNGFR were highest in the adult adrenal cortex. Cur data suggest still largely enigmatic roles for neurotrophins in functions of the adrenal medulla and possibly also the cortex.

Adrenal Glands↗
PubMed1996

Regulation of connexin-43, GFAP, and FGF-2 is not accompanied by changes in astroglial coupling in MPTP-lesioned, FGF-2-treated parkinsonian mice.

Basic fibroblast growth factor (bFGF; FGF-2) has potent trophic effects on developing and toxically impaired midbrain dopaminergic (DAergic) neurons which are crucially affected in Parkinson's disease. The trophic effects of FGF-2 are largely indirect, both in vitro and in vivo, and possibly involve intermediate actions of astrocytes and other glial cells. To further investigate the cellular and molecular mechanisms underlying the restorative actions of FGF-2, and to analyse in more detail the changes within astroglial cells in the MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-lesioned striatum, we have studied striatal expression and regulation of connexin-43 (cx43), the principal gap junction protein of astroglial cells, along with the expression of glial fibrillary acidic protein (GFAP), FGF-2, and functional coupling. Our results show an immediate, yet transient increase in cx43 mRNA, and a sustained increase in FGF-2 mRNA, GFAP-positive cells, and cx43-immunoreactive punctata following the MPTP lesion, without any induction of functional coupling between astrocytes and other glial cells as revealed by dye coupling of patched cells. Unilateral administration of FGF-2 in a piece of gelfoam caused a further increase in cx43-positive punctata immediately adjacent to the implant, which was more pronounced than after application of a gelfoam containing the nontrophic control protein cytochrome C. These changes were parallelled by a small increase in cx43 protein determined by Western blot, but not by alterations in the coupling state of cells in the vicinity of the gelfoam implant. Although our data indicate that MPTP and exogenous FGF-2 may alter expression and protein levels of cx43, they do not support the notion that increases in cellular coupling may underly the trophic and widespread actions of FGF-2 in the MPTP-model of Parkinson's disease.

Animals↗
PubMed1996

Expression of TGF-beta type II receptor mRNA in the CNS.

Members of the TGF-beta family have been described to bind to a heteromeric complex of two types of serine/threonine kinase receptors, named T beta R-I and T beta R-II. These receptor molecules are essential for TGF-beta-specific signalling. Several type I and type II receptors have been identified by a variety of methods. TGF-beta 2 and 3 are widely expressed in the CNS and exert multiple functions on neurones and glia. Although the T beta R-I molecule is abundant in the CNS, it was unclear whether the type II receptor found in peripheral organs is also expressed in the CNS. Previous, negative findings, seemed to suggest that a novel, as yet undescribed type II receptor may be expressed in the CNS. We used competitive RT-PCR to detect T beta R-II mRNA in rats at different stages of development (E18, P6, adult) and in different tissues. We detected this mRNA in the lung, liver, heart, gut, kidney, and pituitary of adult rats. Surprisingly, and in contrast to previous studies, similar levels of the T beta R-II mRNA were also detected in several regions of the CNS, namely cortex, midbrain, cerebellum, brain stem and hippocampus. We therefore tentatively conclude that TGF-beta 2 and 3 may signal in the brain by means of the same type-I and -II receptors as found in peripheral organs.

Aging↗
PubMed1996

GDNF mRNA levels are induced by FGF-2 in rat C6 glioblastoma cells.

Glia cell line-derived neurotrophic factor (GDNF), a recently cloned member of the transforming growth factor-beta (TGF-beta) superfamily, has been implicated in the survival, morphological and functional differentiation of midbrain dopaminergic neurons and motoneurons in vitro and in vivo. The factor may thus have utility in the treatment of various human neurodegenerative disorders. Mechanisms regulating expression of GDNF in normal and diseased brain as a possible means to increase the local availability of GDNF are only beginning to be explored. We have established and employed a competitive reverse transcriptase-polymerase chain reaction (RT-PCR) to study and compare levels of expression of GDNF mRNA in several cell types and to investigate its regulation. GDNF expression was clearly evident in primary cultured astrocytes, the glioma B49 and C6 cell, but less pronounced in the Schwannoma RN22 cell lines. Little or no signal could be observed in neuroblastoma cell lines (IMR32, LAN-1) or the pheochromocytoma cell line PC12, emphasizing the glial character of this factor. Using the C6 cell line we found that fibroblast growth factor-2 (FGF-2; bFGF) can increase GDNF mRNA levels, whereas FGF-1, platelet-derived growth factor (PDGF), and vasoactive intestinal polypeptide (VIP) are apparently ineffective. Several other factors (forskolin, kainic acid, triiodothyronine dexamethasone, GDNF, TGF-beta 1, and interleukin-6) appear to have slightly negative effects on GDNF mRNA levels at the concentrations tested. To further explore the relationship between FGF-2 and GDNF, we also addressed the question whether GDNF, like FGF-2, may have an effect on C6 cell proliferation. We conclude that (1) glial and glial tumor cells, rather than neuronal cell lines, express GDNF, (2) that FGF-2 has a prominent inductive effect on GDNF expression and (3) that GDNF stimulates C6 cell proliferation. Finally, these data suggest that neurotrophic actions of FGF-2 in mixed glial-neuronal cell cultures might be mediated in part by GDNF.

Animals↗
PubMed1996

Proteins from chromaffin granules promote survival of dorsal root ganglionic neurons: comparison with neurotrophins.

Neurotrophins are established survival and differentiation factors for sensory dorsal root ganglionic (DRG) neurons. We have previously shown that proteins from the secretory granules of adrenal chromaffin cells have a capacity to promote the survival of cultured chick DRG neurons. Using DRG neurons from embryonic day (E) 8 chick embryos we show now that this material is (i) as effective as nerve growth factor (NGF), (ii) additive to NGF, neurotrophin-3, or -4, (iii) unlikely to be a neurotrophin, since the survival promoting effect can not be blocked by K252b, a specific inhibitor of the signal transduction pathways of neurotrophin high affinity receptors, (iv) partially blockable by antibodies to transforming growth factor-beta (TGF-beta) 1/2/3, and (v) more potent than any other out of 30 cytokines tested individually, including fibroblast growth factor (FGF)-5, epidermal growth factor (EGF), TGF-alpha, platelet-derived growth factor (PDGF)-AB, insulin-like growth factors (IGF)-I and -II, leukemia inhibitory factor (LIF), TGF-beta, glial cell line-derived neurotrophic factor (GDNF), stem cell factor, granulocyte-colony stimulating factor (G-CSF), oncostatin M, tumor necrosis factor (TNF)-alpha, and interleukins (IL)-1 through -12. We conclude that chromaffin cells, which are known to receive a sensory innervation, can provide (a) trophic factor(s), which, in addition to neurotrophins, may be relevant for the maintenance of DRG neurons.

Animals↗
PubMed1996

Expression, localization, and function of transforming growth factor-beta s in embryonic chick spinal cord, hindbrain, and dorsal root ganglia.

We have studied the localizations of transforming growth factor-beta (TGF-beta) 2 and 3 immunohistochemically using isoform-specific antibodies and TGF-beta 3 mRNA by in situ hybridization in the nervous system of the 3- to 15-day-old chick embryo with special reference to spinal cord, hindbrain, and dorsal root ganglia (DRG). At embryonic day (E) 3, TGF-beta 3 mRNA as well as TGF-beta 2 and 3 immunoreactivities (IRs) were most prominent in the notochord, wall of the aorta, and dermomyotome. At E5 and E7, strong TGF-beta 2 and 3 IR were seen in or on radial glia of spinal cord and hindbrain. Radial glia in the floor plate region and ventral commissure gave the most intense signal. In the DRG, fiber strands of intense IRs representing extracellular matrix or satellite cells were seen. Neuronal perikarya did not become IR for TGF-beta 2 and 3 until E11, but even then the moderate signals for TGF-beta 3 mRNA could not be specifically localized to the neuronal cell bodies. In E11 and older embryos, spinal cord glial or glial progenitor cells, but not neuronal cell bodies were labeled for TGF-beta 3 mRNA. Immunocytochemistry and western blot analysis indicated that E8 DRG neurons have the TGF-beta receptor type II, and treatment of these cells with NGF induces expression of TGF-beta 3 mRNA. The TGF-beta isoforms 1, 2, and 3 did not promote survival of E8 DRG neurons in dissociated cell cultures. All three TGF-beta isoforms, however, promoted neurite growth from E8 DRG explants, but were less potent than nerve growth factor. Our data suggest identical localizations of TGF-beta 2 and -beta 3 IR in the developing chick and mammalian nervous systems, underscoring the general importance of TGF-beta s in fundamental events of neural development.

Animals↗
PubMed1996

Growth factor function in the development and maintenance of midbrain dopaminergic neurons: concepts, facts and prospects for TGF-beta.

Dopaminergic neurons of the nigrostriatal system are important in the control of motor performance and degenerate in Parkinson's disease. Therefore, in order to design novel strategies for the treatment of Parkinson's disease, it is important for us to understand their development, function, trophic factor requirements, plasticity and susceptibility to toxic influences. A large and still increasing number of growth factors have been implicated in the regulation of the survival and differentiation of dopaminergic neurons. These factors may also protect against a variety of toxic influences. On the basis of their localization, putative sources and mechanisms of actions, such growth factors fall into several categories: (i) local factors within the midbrain influencing proliferation, transmitter phenotype, migration, positioning and neurite growth of stem cells and early neurons; (ii) factors acting retrogradely from the striatum, which are responsible for intrastriatal sprouting and navigation of newly arrived axons as well as life-long maintenance of the dopaminergic nigrostriatal connection; (iii) factors coming into play when the system is toxically impaired; (iv) factors directly acting on dopaminergic neurons; and (v) factors provided by cytokinestimulated astroglia, microglia and neurons affecting dopaminergic neurons anterogradely. This article reviews actions of growth factors on dopaminergic neurons in vitro and in vivo, with a focus on members of the transforming growth factor (TGF)-beta superfamily. TGF-beta s may be particularly relevant to dopaminergic neurons, since they are expressed in the nigrostriatal system from early embryonic stages to adulthood and are significantly up-regulated in response to lesions.

Animals↗
PubMed1996

Early effects of FGF-2 on glial cells in the MPTP-lesioned striatum.

Fibroblast growth factor-2 (FGF-2), locally administered in gelfoam to the striatum of mice treated with the neurotoxic drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), has restorative and neuroprotective effects on dopaminergic neurons and associated striatal transmitter systems. Most of the beneficial alterations are apparently indirect. FGF-2 must therefore act through a series of cellular and molecular intermediate steps, which have not been explored. We have previously shown that FGF-2 does not significantly affect the astroglial reaction at the time, when the neuroprotective effect of FGF-2 reaches a peak (Day 11). In this study we have investigated the effect of FGF-2 at earlier time points after MPTP treatment. We report now that as early as 6 h after administration of the gelfoam containing either FGF-2 or control protein, FGF-2 immunoreactivity disappears from astroglial nuclei, while appearing in small ramified GFAP- and S-100-negative cells, most likely microglia. At 18 h, numbers and staining intensities of GFAP-ir astroglial cells are greater in FGF-2- than in cytochrome C-treated animals. At this time FGF-2-ir reappears in astroglia nuclei of cytochrome C-treated animals, but remains undetectable in the striatum carrying the FGF-2-containing gelfoam. Ramified GFAP/S-100-negative presumed microglial cells are now intensely ir for FGF-2. Signs of an FGF-2-mediated astrogliotic reaction are very pronounced at 18 h and 2 days, but no longer at 11 days, when the astrogliosis reaction has become equally strong in FGF-2- and cytochrome C-treated striata. Our results suggest that administration of FGF-2 to the MPTP-lesioned striatum has early effects on astro- and presumed microglia cells, notably on the nuclear FGF-2-ir of astrocytes. These changes may be involved in mediating the neuroprotective effects of FGF-2 in the MPTP-model of Parkinsonism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1996

Microencapsulated ciliary neurotrophic factor: physical properties and biological activities.

Controlled drug release in the CNS and PNS is still an obstacle to the treatment of neurodegenerative disorders. We have prepared a variety of microspheres containing either ciliary neurotrophic factor (CNTF) or genetically engineered cells able to synthesize and release this cytokine. CNTF is a multifunctional cytokine that can regulate the survival and differentiation of many types of developing and adult neurons. However, when given in therapeutically effective doses by systemic injections, it produces numerous adverse side effects. In order to minimize these effects we have microencapsulated it in biopolymers (chitosans, alginates, and copolymers in various proportions to achieve different kinetic properties). Size distribution profiles were determined by an image analysis system and surface characteristics were assessed by electron microscopy. The total content of CNTF as well as the amounts released per day were determined by ELISA and in vitro bioassays. The results from the release kinetics demonstrate that long-term secretion (up to 24 days) of CNTF is achieved by combining chitosan with copolymerized lactic and glycolic acid, whereas microspheres made of alginate provided only relatively short-term release (2-12 days). Neuron survival and neurite outgrowth in cultures of ciliary ganglia were supported by microencapsulated CNTF, indicating biological stability of CNTF. Genetically engineered human kidney cells 293 continued synthesizing CNTF within spheres and the released amounts of CNTF in the culture medium were comparable to the amounts secreted from monolayers (1 ng/ml of supernatant from confluent cultures) or even higher. These studies provide a basis for future testing of CNTF in encapsulated preparations using animal models of neurodegenerative disorders.

Alginates↗