Ganglioside structures and distribution: are they localized at the nerve ending?

GABAergic neurons of rodent brain correspond partially with those staining for glycoconjugate with terminal N-acetylgalactosamine

Sections of fixed, paraffin-embedded brain from mice and rats were stained with agglutinin from Vicia villosa conjugated to horseradish peroxidase (VVA-HRP) to localize glycoconjugate containing terminal N-acetylgalactosamine (GalNAc). VVA-HRP binding sites were localized in periodic foci at the surface of a selective population of non-pyramidal interneurons in layers II through IV of the rodent cerebral cortex. These multipolar interneurons were shown to utilize gamma-aminobutyric acid (GABA) as a transmitter and thus to be GABAergic by their immunostaining for glutamic acid decarboxylase (GAD) throughout the cytoplasm in serial sections. Pyramidal and other non-pyramidal cortical neurons received GABAergic input as evidenced by punctate immunostaining for GAD on their soma and proximal dendritic arborizations, but these cells failed to show VVA affinity or cytosolic GAD reactivity. Most neurons in the thalamic reticular nucleus stained for the presence of glycoconjugate with terminal GalNAc on their surface and for GAD in the cytosol. In contrast, cerebellar Purkinje cells showed strong cytosolic reactivity with anti-GAD but lacked surface staining with VVA-HRP. These observations show that some but not other populations of GABAergic neurons possess binding capacity for VVA on their surface. The surface of neurons in the deep cerebellar nucleus stained heavily with VVA but failed to show clear cytosolic reactivity for GAD. Some neurons with surface glycoconjugate containing terminal GalNAc are therefore not GABAergic.

Lateral diffusion of ganglioside GM1 in phospholipid bilayer membranes

The lateral diffusion coefficient of ganglioside GM1 incorporated into preformed dimyristoylphosphatidylcholine (DMPC) vesicles has been investigated under a variety of conditions using the technique of fluorescence photobleaching recovery. For these studies the fluorescent probe 5-(((2-Carbohydrazino)methyl)thio)acetyl) amino eosin was covalently attached to the periodate-oxidized sialic acid residue of ganglioside GM1. This labeled ganglioside exhibited a behavior similar to that of the intact ganglioside, and was able to bind cholera toxin. The lateral diffusion coefficient of the ganglioside was dependent upon the gel-liquid crystalline transition of DMPC. Above Tm the lateral diffusion coefficient of the ganglioside was 4.7 X 10(-9) cm2 s-1 (with greater than 80% fluorescence recovery). This diffusion coefficient is significantly slower than the one previously observed for phospholipids in DMPC bilayers. The addition of increasing amounts of ganglioside, up to a maximum of 10 mol %, did not have a significant effect on the lateral diffusion coefficient or in the percent recovery. At 30 degrees C, the lateral mobility of ganglioside GM1 was not affected by the presence of 5 mM Ca2+, suggesting that, at least above Tm, Ca2+ does not induce a major perturbation in the lateral organization of the ganglioside molecules. The addition of stoichiometric amounts of cholera toxin to samples containing either 1 or 10 mol % ganglioside GM1 produced only a small decrease in the measured diffusion coefficient. The fluorescence recovery after photobleaching experiments were complemented with excimer formation experiments using pyrene-phosphatidylcholine. Above the transition temperature the presence of 10 mol % ganglioside GMI induced a large decrease in the rate of excimer formation. These results also indicated that the addition of ganglioside GMI to phospholipid bilayer vesicles induces a significant restriction in the lateral mobility parameters of the lipid bilayer and that the presence of Ca2' does not have a further effect in the mobility of the probe molecules.

Ganglioside-induced regeneration and reestablishment of axonal continuity in spinal cord-transected rats

In this study we examined the effect of chronic GM-1 ganglioside treatment on the reestablishment of axonal continuity and functional recovery in spinal cord-transected rats. Previous studies have shown that chronic treatment with GM-1 ganglioside is effective in producing regeneration of lesioned mesostriatal dopaminergic neurons in the central nervous system [1, 2]. In addition, GM-1 ganglioside advances peripheral nerve regeneration following nerve crush injury [12]. Axonal continuity was determined by the ability of the spinal cord to transport horseradish peroxidase across the region of transection. Comparisons between ganglioside-treated and saline-treated controls showed that ganglioside treatment resulted in the reestablishment of axonal continuity between the spinal cord distal to the level of the transection and the brainstem. Saline-treated controls showed little evidence of axonal continuity between these two regions. Thus gangliosides induce reestablishment of axonal continuity and thereby could advance functional recovery in rats following spinal cord transection.

Selective cytochemical demonstration of glycoconjugate-containing terminal N-acetylgalactosamine on some brain neurons

Paraffin embedded sections of rat, mouse, dog, and human brain were stained with a battery of lectin-horseradish perioxidase conjugates to localize and characterize glycoconjugates. In the rat and mouse cerebral cortex, a subpopulation of nonpyramidal neurons stained selectively with three lectins with specific affinity for terminal N-acetylgalactosamine (GalNAc). These and only these lectins stained the surface of the cell body, dendritic shafts, and proximal parts of the dendritic arborization. Most reactive, nonpyramidal neurons revealed a multipolar dendritic pattern, but some possibly belonged to the bitufted and bipolar types of neuron. The GalNAc-containing neurons appeared widely distributed in layers II-VI with relatively greater abundance in layers IV and V. In the cortex of rats and mice the stained neurons occurred in moderate numbers in the frontal, frontoparietal, striate, retrosplenial, and entorhinal regions, but were less numerous in the hippocampal gyrus, dentate gyrus, and olfactory area. Other neurons in the basal ganglia and brain stem stained weakly for GalNAc. Examination of the frontal cortex of human and canine brains showed a similar distribution of nonpyramidal neurons with affinity for GalNAc-binding lectins. At high magnification, the surface staining of neurons in the cerebral cortex, deep cerebellar nucleus, and other sites appeared periodic rather than continuous. The periodic character of the neuronal surface staining suggested a location for the reactive glycoconjugate in or between the synapses. The GalNAc-containing glycoconjugate occurred in a selected cell type, failed to bind the other lectin conjugates, and differed from biochemically detected glycoconjugates. It is, therefore, considered a newly recognized entity of possible physiologic significance for a population of cortical neurons.

Ganglioside GM1, a molecular target for immunological and toxic attacks: similarity of neuropathological lesions induced by ganglioside-antiserum and cholera toxin

Ganglioside-antisera, the ganglioside GM1-ligands, cholera toxin (CT), and CT subunit B, respectively, were injected into the lumbosacral subarachnoid space of normal rats. The cytotoxic effects of the injected compounds on the peripheral and central nervous system were investigated by light and electron microscopy; the severity of CNS lesions was evaluated by quantitation of macrophages containing debris. In contrast to control sera and GM2-antiserum, antisera against a mixture of the major brain gangliosides GM1, GD1a, GD1b, and GT1b (MaBG) or against GM1 induced demyelination in spinal roots and spinal cord, as well as alterations of astroglia. CT induced the same cytotoxic effects as MaBG- and GM1-antisera, whereas CT subunit B was without effect. The ineffectiveness of GM2-antiserum is obviously due to the very low concentration of the specific binding target, GM2, on cell surfaces; that of CT subunit B to the lack of the cytotoxic operator, subunit A. Our results indicate that a similar pattern of neuropathological lesions may be effected by different cytotoxic mechanisms through attachment of the cytotoxic agent onto the cell surface via a common target molecule, and further substantiate the role of GM1-antibodies in the pathogenesis of demyelination.

Molecular specificity of ganglioside effects on neurite regeneration of sensory neurons in vitro

Highly purified preparations of individual gangliosides have been tested for their ability to modulate the survival and morphological differentiation of embryonic chick dorsal root ganglion neurons. When added at 48 h to established cultures of nerve growth factor (NGF)-dependent neurons, all ganglioside species tested increased the expression of neurofilament protein. Poly- and trisialogangliosides were more effective than di- or monosialogangliosides. In contrast, neither NGF nor an antiserum against NGF influenced neurofilament protein expression over this period of culture. In addition, ganglioside-induced expression of neurofilament protein was not inhibited by the anti-NGF serum.

Retinol transport proteins and concentrations in human amniotic fluid, placenta, and fetal and maternal sera

1. The proteins binding retinol, and retinol concentrations, were determined in amniotic fluid, placental cytosol and in the fetal and maternal circulation. 2. In non-pregnant women, plasma retinol was almost exclusively found in a transthyretin-retinol-binding-protein complex whereas, in pregnant women, retinol-binding-protein-bound retinol was observed not complexed to transthyretin. This latter fraction increased in concentration with fetal age. These two fractions were the major retinol-protein complexes in amniotic fluid and their relative amounts changed with progress of gestation. 3. In fetal blood both of these fractions were again found, with higher proportions of retinol-binding-protein-bound retinol in the umbilical artery than in the umbilical vein.

The patterns of brain gangliosides of Rana catesbeiana during metamorphosis and in the adult

Ganglioside patterns were quantitated for brains of bullfrog (Rana catesbeiana) at three stages of metamorphosis and adult. At each stage nine gangliosides were identified by mobility on silica gel thin-layer chromatograms, and quantitated on the basis of sialic acid content. A single band with chromatographic mobility close to that of GD2, and doublets close to GT1b and GQ were quantitatively the major ones (over 16% each). Doublets close to GM1 and GD1b and a single band slightly behind GD1a made up 5-10% each. A doublet comigrating with GM3, and bands close to GM2 (trace) and GD3 were present in smaller amounts. The only developmental trend was a slight increase in the proportion of the band close to GD3 from 2.4% (early prometamorphic phase) to 9.1% (adult). This suggests that changes in the regenerative capacity of frog nervous tissues during metamorphosis are due to changes other than ganglioside composition.

Ganglioside GM1 does not initiate, but enhances neurite regeneration of nerve growth factor-dependent sensory neurones

An enzyme-linked immunoadsorbent assay (ELISA) for neurofilament protein was utilised to quantify the effect of exogenous ganglioside on neurite regeneration in cultures of dorsal root ganglion neurones. In contrast to nerve growth factor (NGF), ganglioside GM1 (100 micrograms/ml) failed to support neuronal survival and neurite regeneration as quantified by the ELISA assay and confirmed by morphological criteria. However, the simultaneous presence of GM1 (100 micrograms/ml) and NGF (0.5-5 ng/ml) throughout a 5-day period of culture resulted in an enhancement of previously reported NGF-induced increases in the expression of neurofilament protein. Further, the addition of GM1 (0-200 micrograms/ml) at 48 h in vitro to cultures initially established in the presence of 5 ng/ml NGF substantially increased the subsequent expression of neurofilament protein, this response being both independent of and not potentiated by NGF. The results in the present system suggest that GM1 cannot initiate a programme of neurite regeneration; however, GM1 can enhance this process with the response being secondary to the effect of NGF.

Axonal transport of glycoconjugates in the rat visual system

Long-Evans rats at 45 days of age were injected intraocularly with 25 mu Ci of [3H]glucosamine. Incorporation of radioactivity into retinal gangliosides, glycoproteins, and glycosaminoglycans (GAGs) was determined at various times after injection. Portions of all three classes of radioactive macromolecules were committed to rapid axonal transport in the retinal ganglion cells. With respect to gangliosides about 60% of those synthesized in the retina were retained in that structure, 30% were committed to transport to regions containing the nerve terminal structures (lateral geniculate body and superior colliculus), and about 10% were deposited in stationary structures of the axons (optic nerve and tract). With the exception of ganglioside GD3 the molecular species distribution of gangliosides synthesized in the retina matched that committed to transport. In contrast to gangliosides a smaller fraction of newly synthesized retinal glycoprotein (less than 12% of that synthesized in the retina) was committed to rapid transport to nerve ending regions and only about 0.5% was retained in the nerve and tract. The molecular-weight distribution of glycoproteins committed to transport differed quantitatively from that of the retina. With respect to GAGs an even smaller portion (1-2%) of that synthesized in the retina was committed to rapid transport; of this portion almost all was recovered in nerve terminal-containing structures. A constant proportion of each retinal GAG species was transported to the superior colliculus. We suggest that most of the retinal gangliosides are synthesized in neurons and preferentially in ganglion cells (possibly a function of the large surface membrane area supported by these cells). Subcellular fractionation experiments indicated that transported gangliosides, glycoproteins, and GAGs may be preferentially distributed into different subcellular compartments.

Ganglioside headgroups decrease lipid order in reconstituted phosphatidylcholine liposomes

The effect of oligosaccharide carrying lipids on membrane fluidity has been investigated. Gangliosides GM1 and GQ1 were reconstituted into phosphatidylcholine bilayer membranes at low concentrations (less than 5 mol%). A strong fluidizing effect was observed leading to a suppression of the phase transition temperature. This was most pronounced with highly sialylated gangliosides. Ca2+ reverses the effect due to phase separation phenomena. We assume a hydrophilic lipid-lipid interaction in accordance with previously studied glycoprotein-lipid interactions.

GM1 ganglioside does not stimulate reinnervation of the striatum by substantia nigra grafts

Ganglioside GM1 has been reported to promote reinnervation of the striatum by dopaminergic fibers following brain hemisection in the rat. In the present study, the possibility that chronic ganglioside GM1 (10 or 50 mg/kg day for 3 weeks) would promote reinnervation of the dopamine-denervated striatum by embryonic substantia nigra grafts was studied. No enhancement of the ingrowth of fibers from the grafts was observed. It is concluded that under this circumstance, the growth of catecholaminergic fibers is restricted by factors other than the availability of ganglioside GM1.

Plasma concentrations of N-acetylneuraminic acid in severe malnutrition

In rat studies, circulating concentrations of N-acetylneuraminic acid (NANA) have been shown to be an indicator of NANA concentrations in the brain and functional brain activity, in relation to nutritional state and stimulation. Abnormal behaviour can be improved with exogenous NANA. In the present study, the plasma NANA concentration has been measured in children with severe malnutrition and compared with that in controls. NANA was measured colorimetrically in the plasma of twenty-three severely malnourished children (mean age 11.43 (SD 6.05) months) before and after recovery, and in thirty-four controls (mean age 14.28 (SD 7.32)months). In thirteen of the malnourished children, NANA was measured after infections had been treated with a course of antibiotics. Mean plasma NANA concentration was significantly higher in protein-energy malnutrition (PEM) (2.89 (SD 0.58) mumol/ml; n 23) compared with controls (2.13 (SD 0.37) mumol/ml; n 34, P less than 0.001). The levels remained high in PEM after infections had been treated (2.87 (SD 0.43) mumol/ml, n 13) but returned to control levels at recovery from PEM (2.14 (SD 0.24) mumol/ml). In contrast to the findings in rats, in malnourished children plasma NANA concentrations were not reduced and did not relate directly to nutritional state or, by inference, brain function. These findings do not provide any support for the use of exogenous NANA supplements to improve brain function in humans.

Lipids of nervous tissue: composition and metabolism

As indicated in the Introduction, the many significant developments in the recent past in our knowledge of the lipids of the nervous system have been collated in this article. That there is a sustained interest in this field is evident from the rather long bibliography which is itself selective. Obviously, it is not possible to summarize a review in which the chemistry, distribution and metabolism of a great variety of lipids have been discussed. However, from the progress of research, some general conclusions may be drawn. The period of discovery of new lipids in the nervous system appears to be over. All the major lipid components have been discovered and a great deal is now known about their structure and metabolism. Analytical data on the lipid composition of the CNS are available for a number of species and such data on the major areas of the brain are also at hand but information on the various subregions is meagre. Such investigations may yet provide clues to the role of lipids in brain function. Compared to CNS, information on PNS is less adequate. Further research on PNS would be worthwhile as it is amenable for experimental manipulation and complex mechanisms such as myelination can be investigated in this tissue. There are reports correlating lipid constituents with the increased complexity in the organization of the nervous system during evolution. This line of investigation may prove useful. The basic aim of research on the lipids of the nervous tissue is to unravel their functional significance. Most of the hydrophobic moieties of the nervous tissue lipids are comprised of very long chain, highly unsaturated and in some cases hydroxylated residues, and recent studies have shown that each lipid class contains characteristic molecular species. Their contribution to the properties of neural membranes such as excitability remains to be elucidated. Similarly, a large proportion of the phospholipid molecules in the myelin membrane are ethanolamine plasmalogens and their importance in this membrane is not known. It is firmly established that phosphatidylinositol and possibly polyphosphoinositides are involved with events at the synapse during impulse propagation, but their precise role in molecular terms is not clear. Gangliosides, with their structural complexity and amphipathic nature, have been implicated in a number of biological events which include cellular recognition and acting as adjuncts at receptor sites. More recently, growth promoting and neuritogenic functions have been ascribed to gangliosides. These interesting properties of gangliosides wIll undoubtedly attract greater attention in the future.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution of the ganglioside GD3 in the human nervous system detected by R24 mouse monoclonal antibody

Immunohistochemical staining with mouse monoclonal antibody R24 recognizing the ganglioside GD3 was used to study the distribution of GD3 in the human brain. Positive staining was primarily found in the surrounding neuropil of many neuronal groups in the brainstem and spinal cord, cerebellum, retina and dentate gyrus of hippocampus. In addition, staining was found in ependymal cells and glial processes around blood vessels and in the subependymal region.

GM1 ganglioside enhances regrowth of noradrenaline nerve terminals in rat cerebral cortex lesioned by the neurotoxin 6-hydroxydopamine

The effect of exogenous GM1 ganglioside on selectively noradrenaline-denervated rat cerebral cortex was investigated by measuring the spatial distribution of endogenous noradrenaline levels and by fluorescence histochemical analysis. A local noradrenaline denervation was produced by intracortical infusion of the selective catecholamine neurotoxin 6-hydroxydopamine for 3 or 7 days. The neurotoxin infusion caused an almost complete noradrenaline denervation in a restricted area around the infusion point as reflected by an almost complete long-term disappearance of noradrenaline nerve terminals and reduction of noradrenaline levels. There was with time a slow recovery of the levels, most likely related to a spontaneous noradrenaline nerve terminal regeneration. Post-treatment for 1 week with GM1 had very small effects on the 6-hydroxydopamine-induced reduction of the noradrenaline levels, while pretreatment with GM1 for 3 days before the neurotoxin infusion and continuing the GM1 administration for another 7-14 days significantly enhanced noradrenaline recovery, as observed both bio- and histochemically. GM1 had no effect on the 6-hydroxydopamine-induced noradrenaline depletion acutely, indicating that GM1 does not interfere with the direct neurotoxic actions of 6-hydroxydopamine. The present results thus indicate that exogenous GM1 enhances regrowth of noradrenaline nerve terminals which may be due to a regrowth stimulatory effect (regeneration/collateral sprouting) and/or related to protective actions of GM1 against retrograde degeneration of noradrenaline axons following the neurotoxin-induced lesion.

A rapid preparative method for isolation of neutral and acidic glycosphingolipids by radial thin-layer chromatography

An efficient method to separate neutral and acidic glycosphingolipids (GSLs) from their mixtures within a short period (45-60 min) and with low consumption of solvents (chloroform-methanol-water, 60/35/8 (v/v/v); 250-500 ml) has been developed. This method utilizes a centrifugal thin-layer chromatograph (Chromatotron) and the GSL mixtures (30-400 mg) are applied to glass plates coated with a 1-mm layer of silica gel 60 PF-254. The method (radial thin-layer chromatography) is rapid and simple and the recovery of glycosphingolipids is high (70-80%).

Effect of GM1 ganglioside treatment on the recovery of dopaminergic nigro-striatal neurons after different types of lesion

The effect of GM1 ganglioside treatment on the recovery of biochemical and behavioral parameters which define the activity of nigro-striatal dopaminergic systems has been investigated in rats after different types of lesion. GM1 favours the recovery of tyrosine-hydroxylase activity, of the number and affinity of 3H-N-n-propyl-norapomorphine binding sites in the striatum of the lesioned side and reduces the apomorphine-induced rotational behavior after mechanical (i.e. unilateral hemitransection) but not after chemical (i.e. 6-OHDA injected in the substantia nigra) lesion. The source of regrowing dopaminergic nerve terminals in the striatum after hemitransection is mainly a response of intact remaining axons of the ipsilateral side. Moreover the contralateral nigro-striatal systems seems to play, through intrathalamic connections, an important role in regulating the GM1-induced increase of the tyrosine-hydroxylase activity.

Effect of GM1 ganglioside on neonatally neurotoxin induced degeneration of serotonin neurons in the rat brain

The effect of exogenous GM1 ganglioside on the 5,7-dihydroxytryptamine (5,7-HT; a selective serotonin neurotoxin) induced alteration of the postnatal development of central 5-hydroxytryptamine (5-HT; serotonin) neurons has been investigated using neuro-chemical and immunocytochemical techniques. Neonatal 5,7-HT (50 mg/kg s.c.) treatment is known to lead to a marked and a permanent degeneration of distant 5-HT nerve terminal projections (e.g. in cerebral cortex, hippocampus and spinal cord), while projections close to the 5-HT perikarya in the mesencephalon and pons-medulla increase their nerve density. These regional alterations are reflected by decreases and increases, respectively, of endogenous 5-HT, [3H]5-HT uptake in vitro and number of 5-HT nerve terminals demonstrated by immunocytochemistry. Treatment of newborn rats with GM1 (4 X 30 mg/kg s.c.; 24 h interval) had no significant effect on the postnatal development of 5-HT neurons. GM1 administration had furthermore no effect on the 5,7-HT induced alteration of the regional 5-HT levels and [3H]5-HT uptake in the cerebral cortex acutely, indicating that GM1 did not significantly interfere with the primary neurodegenerative actions of 5,7-HT. At the age of 1 month a clear counteracting effect of GM1 was observed, in particular of the 5,7-HT induced 5-HT denervations. The 5-HT levels in the frontal and occipital cortex were reduced to 25 and 20% of control after 5,7-HT alone, while these values were 70 and 40%, respectively, after 5,7-HT and GM1 treatment. A similar antagonizing effect of GM1 was found in the frontal cortex when measuring [3H]5-HT uptake. GM1 treatment also caused a minor reduction of the 5,7-HT induced increase of the 5-HT levels in striatum and mesencephalon. Quantitation of 5-HT nerve terminal density in sections processed for 5-HT immunocytochemistry using an automatic image analysis system showed markedly more nerve terminals in the frontal and occipital cortex after 5,7-HT + GM1 compared to 5,7-HT treatment alone. Minor counteracting effects of GM1 were noted in the hippocampus and spinal cord (thoracic-lumbar) as evaluated by chemical 5-HT assay, although substantial counteracting effects were observed locally in these areas by quantitative immunocytochemistry.(ABSTRACT TRUNCATED AT 400 WORDS)

Topographical atlas of the gangliosides of the adult human brain

Forty different brain samples, consisting of neocortical, archicortical, and paleocortical areas; telencephalic, diencephalic, and mesencephalic subcortical nuclei; and the cerebellum as well as some of the corresponding white matter bundles were analyzed with respect to total content of ganglioside-sialic acid and the ganglioside pattern. The total content of gangliosides seems to depend mainly on the proportions of gray and white matter. Thus, neocortical areas, which are rich in gray matter, have a four- to fivefold higher ganglioside content (per milligram of protein) than white matter-rich samples such as optic chiasm, capsula interna, or corpus callosum. White matter-rich regions, although very heterogeneous in ganglioside composition, are further characterized by appreciable amounts of the myelin-enriched GM4. In the neocortex a remarkable degree of regional pattern differences was revealed. In the frontal and parietal areas there is a moderate, and in the temporal region a strong preponderance of sialic acid bound to gangliosides of the a-pathway (GD1a, GM1). In contrast, the occipital cortex favors the b-pathway of ganglioside synthesis (GQ1b, GT1b, GD1b). A predominance of "b-gangliosides" was found in all structures that are related to the visual system (optic chiasm, pulvinar-thalamus, superior colliculi, visual cortex) as well as in the cerebellum and the nucleus ruber. All diencephalic nuclei tend to favor slightly "b-gangliosides," while the mesencephalic nuclei are very heterogeneous in their ganglioside composition. A preponderance of "a-gangliosides" was found in the periamygdalar cortex, putamen, inferior colliculi, substantia nigra, frontal white matter, internal capsule, globus pallidus, basal nucleus of Meynert, and corpus callosum as well as in the frontal, parietal, and temporal cortices. An exceptional predominance of GM1 and GD1a was revealed for the hippocampal archicortex and the amygdala, suggesting a possible functional correlation to glutaminergic synaptic transmission.

Adrenocorticotropic hormone (ACTH)-lipid interactions. Implications for involvement of amphipathic helix formation

ACTH-lipid interactions were investigated by: (1) lipid-monolayer studies using several zwitterionic and anionic phospholipids and gangliosides, (2) permeability experiments by following the swelling rate of liposomes in isotonic glycerol solutions by light scattering, using liposomes of synthetic lipids and liposomes made of lipids extracted from light synaptic plasma membranes, and (3) by steady-state fluorescence anisotropy measurements on liposomes derived from light synaptic plasma membranes employing 1,6-diphenyl-1,3,5-hexatriene as fluorescent probe. (1) The monolayer experiments demonstrated an interaction with gangliosides GT1, GM1, dioleoylphosphatidic acid and phosphatidylserine, but little or no interaction with phosphatidylcholine or sphingomyelin. The interaction with monolayers of GT1 or phosphatidic acid decreased for ACTH1-13-NH2 and ACTH1-10. (2) The liposome experiments showed that 2 X 10(-5) M ACTH1-24 increased the glycerol permeability by 20% and decreased the activation energy only when liposomes derived from light synaptic plasma membranes were used. Treatment of the liposomes with neuraminidase abolished the ACTH-induced permeability increase. (3) Steady-state fluorescence depolarization measurements revealed that ACTH1-24, ACTH1-16-NH2 and ACTH1-10 did not change the fluidity of liposomes derived from light synaptic plasma membranes as sensed by diphenylhexatriene. It is concluded that ACTH1-24 can bind to negatively charged lipids and can form an amphipathic helix aligned parallel to the membrane surface involving the N-terminal residues 1 to 12, possibly to 16. Polysialogangliosides will favorably meet the condition of a high local surface charge density under physiological circumstances. It is suggested that ACTH-ganglioside interactions will participate in ACTH-receptor interactions.

GM1 ganglioside treatment facilitates behavioral recovery from bilateral brain damage

Adult rats with bilateral lesions of the caudate nucleus were treated with GM1 ganglioside. Although animals injected with a control solution were severely impaired in their ability to learn a complex spatial task, those treated with ganglioside were able to learn spatial reversals.

Nerve regeneration in exogenous cerebral ganglioside-treated rats

Intraperitoneal injection of 50 mg/kg of exogenous cerebral gangliosides resulted in a statistically significant (23%) increase (compared with saline-injected controls) in the tetanic isometric tension of the rat plantaris muscle 7 days after section of the fourth lumbar root (L4). In a second experiment, intraperitoneal-injected exogenous gangliosides were found to have no effect on axonal regeneration following cryo-injury to the sciatic nerve. These results lead to the possibility of an early enhancement of muscular collateral sprouting in partially denervated muscles under an intraperitoneal-injected ganglioside mixture treatment.

Failure of plasma membranes of astrocytes in primary culture to insert exogenous ganglioside GM1

Primary cultures of astrocytes derived from newborn rat brain cerebral hemispheres did not incorporate ganglioside GM1 into their plasma membranes when cultured in a medium containing the added ganglioside. This finding suggests that the function and/or structure of the astrocyte cell membrane differs from that of the neuron and oligodendroglia cell.

Chronic GM1 ganglioside treatment reduces dopamine cell body degeneration in the substantia nigra after unilateral hemitransection in rat

The effect of GM1 ganglioside on the recovery of dopaminergic nigro-striatal neurons was studied in rats after unilateral hemitransection. GM1 treatment partially prevented the decrease of tyrosine hydroxylase (TH) activity caused by hemitransection in the substantia nigra ipsilateral to the lesion. Concomitantly a significant increase of TH-immunoreactivity in the substantia nigra was also detected. In particular, chronic treatment with GM1 prevented the disappearance of TH-positive cell bodies in the substantia nigra and induced the appearance of longer TH-positive dendrites with respect to the saline treatment. These data indicate that GM1 treatment maintains the number of dopaminergic cell bodies in the substantia nigra after hemitransection by protecting against retrograde neuronal degeneration.

Modulation of neuraminidase activity by the physical state of phospholipid bilayers containing gangliosides Gd1a and Gt1b

The thermotropic behavior of large unilamellar dipalmitoylphosphatidylcholine vesicles containing the disialoganglioside Gd1a and the trisialoganglioside Gt1b on their outer surface has been studied as a function of the ganglioside molar fraction and Ca2+ concentration by using high-sensitivity differential scanning calorimetry and steady-state fluorescence spectroscopy. These studies indicate that both gangliosides have an ordering effect on the hydrocarbon region of the bilayer and that this effect is enhanced by the presence of Ca2+ ions. The calorimetric experiments also indicate that ganglioside Gt1b has an intrinsic tendency to phase separate into compositional-rich ganglioside domains even in the absence of Ca2+. Ganglioside Gd1a, on the other hand, only phase separates at Ca2+ concentrations equal to or higher than 10 mM. These studies have allowed us to identify and evaluate the factors affecting the rates of hydrolysis of gangliosides by the soluble neuraminidase from Clostridium perfringens. The data presented in this paper indicate that the rates of hydrolysis of membrane-bound gangliosides are correlated to the physical state of the membrane and the state of aggregation of the ganglioside molecules within the lipid bilayer. For membrane-bound gangliosides, maximal activation energies were found at temperatures slightly below the lipid phase transition temperature. The rates of hydrolysis of the soluble substrate sialyllactose or that of the micellar ganglioside is independent of Ca2+ concentration, whereas the rates of hydrolysis of membrane-bound ganglioside are inhibited by Ca2+ especially under conditions in which the clustering effect of Ca2+ is maximal. These studies suggest that the soluble neuraminidases from Clostridium perfringens prefer ganglioside substrates that are dispersed within the membrane and not forming part of largely aggregated clusters.

The functional recovery of damaged brain: the effect of GM1 monosialoganglioside

In the present study the topology and the biochemical mechanisms underlying the functional recovery of the dopaminergic nigrostriatal system is further analyzed. Rats with unilateral hemitransection were treated with 30 mg/kg GM1 monosialoganglioside or with its internal ester derivative for different periods of time. GM1 enhances 3H-dopamine uptake in striatal synaptosomes of the lesioned side, and the enhancement of dopamine uptake precedes that of striatal tyrosine hydroxylase activity. The above biochemical effects are accompanied by changes in behavioral- and electrophysiological-related parameters. The effect of GM1 on striatal tyrosine hydroxylase of the lesioned side disappears when the ascending dopaminergic fibers are extensively lesioned. This suggests that the source of regrowing dopaminergic nerve terminals in the striatum of partially lesioned rats resides mainly in the intact axons remaining in the ipsilateral side. When GM1 is injected into partially lesioned rats kept in darkness, no effect on tyrosine hydroxylase activity is observed. This indicates that the mechanism through which GM1 acts involves a normal light-dark cycle.

Biology of gangliosides: neuritogenic and neuronotrophic properties

Research on the biologic function of gangliosides has accelerated in recent years following discovery of their pronounced effects when administered exogenously to neurons in culture and in vivo. These effects are of two principal types: 1) neuronotrophic, concerned primarily with survival and maintenance of the neuron, and 2) neuritogenic, involving significant increase in the number, length, and/or branching of neuronal processes. Such neurite-promoting activity has been observed in primary cultures of neurons from brain and ganglia as well as transformed lines of neuronal origin. These phenomena may be related to the remarkable growth of aberrant secondary neurites, often accompanied by synaptogenesis, observed in the gangliosidoses. Several in vivo studies have shown exogenously administered gangliosides to aid nervous system repair in both the CNS and PNS, although it is not clear in some cases whether the observed effects should be attributed to neuronotrophic or neuritogenic effects (or both). This article attempts to briefly review the principal developments that have occurred in this area of ganglioside research over the past several years. It also presents for consideration some of the tentative hypotheses put forward concerning mechanism of action.

Effects of gangliosides on the functional recovery of damaged brain

The effect of GM1 ganglioside on the recovery of dopaminergic nigro-striatal neurons was studied in rats after unilateral hemitransection. GM1 treatment favoured the collateral sprouting of dopaminergic axons in the striatum as indicated by the induced increase of tyrosine hydroxylase (TH) activity and immunofluorescence. Concomitantly GM1 partially prevented the decrease of TH activity caused by the hemitransection in the substantia nigra ipsilateral to the lesion. A significant increase of TH immunoreactivity was also detected in the substantia nigra: GM1 prevented the disappearance of TH-positive cell bodies and increased the formation of TH-positive collaterals and dendrites with respect to the saline treatment. The addition of GM1 to embryonic dissociated mesencephalic cell cultures stimulates the expression of dopaminergic characteristics as suggested by the increase of 3H-DA uptake.

Ganglioside induced surface activity and neurite formation of Neuro-2a neuroblastoma cells

These studies demonstrate that while microtubules are essential for BBG-mediated neurite initiation and elongation, they are not involved in microfilament-dependent ganglioside-mediated surface activity. Microfilaments may be more directly altered by exogenous gangliosides than microtubules since they are the major structural elements of microvilli and are required for neurite branching. Our studies suggest that normal neuritogenesis requires a delicately balanced interaction between various cytoskeletal elements. Since there is a close relationship between membrane-associated lipid molecules and submembranous cytoskeletal elements, the incorporation of gangliosides into membranes may alter this balance and result in neurite formation. The use of gangliosides to enhance neurite production provides a unique model for the study of nerve development. We have shown that bovine brain gangliosides stimulate an immediate sequence of surface-related changes as well as microtubule and microfilament dependent neurite formation in Neuro-2a cells. However, the precise molecular events by which gangliosides enhance neuritogenesis await further study.

Antibodies to gangliosides inhibit goldfish optic nerve regeneration in vivo

Intraocular injection of antiserum to mixed ganglioside or to GM1 inhibited the regeneration of goldfish optic axons following an optic nerve crush. For example, injections of antiserum on 5 consecutive days beginning the day before the crush resulted in a decrease of about 40% in the axonal outgrowth distance measured at 10 days after the crush. The inhibition was observed even when the treatment was begun a few days after the lesion, and greater degrees of inhibition were observed when the treatment was given later in regeneration. This indicates that the antiganglioside serum interfered with axonal elongation more than with the initial sprout formation. The antiganglioside treatment did not impair the enlargement of the cell bodies and nucleoli that accompanies regeneration, nor did it affect fast axonal transport of protein, glycoprotein, or glycolipid in regenerating nerves. Thus inhibition of outgrowth by antiganglioside treatment was not mediated by a gross change in the metabolism of the regenerating neurons. Treatment of normal neurons with the antiserum produced a 20-30% increase in the amount of 3H-glucosamine-labeled glycoproteins and glycolipids conveyed by fast axonal transport. These results suggest that membrane gangliosides may normally influence the supply of axonally transported glycosylated macromolecules. However, the effect of antiganglioside on axonal transport of glycosylated molecules and on axonal outgrowth are not necessarily related to each other.

Structure related phylogenetic variations in brain gangliosides of vertebrates

The concentration and composition of brain gangliosides from five brain structures of vertebrate species belonging to the classes of Chondrichthyes, Osteichthyes, Reptilia, Aves and Mammalia were investigated. The complexity of brain ganglioside composition is strikingly reduced over phyletic lines. In lower vertebrates there is only little variation in the ganglioside pattern between the different brain structures, whereas in higher vertebrates differences distinctly occurred. A similarity over phyletic lines of ganglioside pattern was only noted in phylogenetically old brain structures as for instance in the medulla oblongata and the brain stem.

Neuronal acquisition of tetanus toxin binding sites: relationship with the last mitotic cycle

In an earlier study on the developing nervous system, the existence of a temporal correlation between the appearance of tetanus toxin-binding cells and neurogenesis was reported (A. Koulakoff, B. Bizzini, and Y. Berwald-Netter (1982). Dev. Brain Res. 5, 139-147). Using a combined approach of immunocytochemistry and [3H]thymidine autoradiography it is shown that, in the fetal mouse central nervous system, dividing cells do not express membrane binding sites for tetanus toxin. A time-course quantitative autoradiography revealed that the toxin-binding sites become apparent within 7 +/- 1 hr, following the last S phase, on cells undergoing the conversion from dividing to postmitotic state. The acquisition of surface binding sites for tetanus toxin may thus be an early property of nascent central neurons, marking the transition from cycling precursor neuroblasts to postmitotic neuronal cells. Parallel studies on in vivo-developing dorsal root ganglia disclosed that at least some peripheral nervous system cells are endowed with tetanus toxin-binding capacity while still capable of DNA synthesis and undergo one or more divisions.

Characterization and partial purification of a ganglioside-associated mitogen

A nonganglioside factor(s) present in Sigma types II and III mixed bovine brain ganglioside preparations synergises with suboptimal amounts of serum to induce proliferation specifically in nondividing B 103 neuroblastoma cultures. The active substance is nondialysable and soluble in water as well as in chloroform-methanol mixtures of 1:1-4:1 (vol/vol). It is completely insoluble in ether and acetone at room temperature. Biological activity survives heating to 70 degrees C in the presence of 0.1 M HCl for 1 h as well as boiling at neutral pH. Loss of activity occurs on heating to 70 degrees C for 1 h with 1 M HCl or 1 M NaOH. The activity is insensitive to digestion with neuraminidase, trypsin, pronase, and phospholipases A2 and C. The factor cochromatographs with gangliosides on Dowex AG 50W and Sephadex G100 and is partially recovered with GM1 on DEAE-Sepharose, but may be isolated in a ganglioside-free fraction by sequential chromatography on Sephadex LH20 and silicic acid columns. The substance(s) has the properties of a water-soluble proteolipid protein, the amino acid composition being reported. It is not immunologically cross-reactive with antibodies to GM1 ganglioside or the major proteolipid protein of myelin.

Gangliosides enhance neurite outgrowth in PC12 cells

Gangliosides are surface membrane components that have been suggested to play a significant role in the regulation of many cellular events including neuronal differentiation, growth and regeneration. We have chosen PC12 cell as a model system to study the influence of exogenously added glycosphyngolipids on in vitro differentiation and regeneration. A mixture of bovine brain gangliosides, (GM1 21%, GD1a 39.7%, GD1b 16% and GT 19%) or purified GM1 and GT respectively were added to culture media containing NGF on plating day and their effect was monitored on alternate days starting on day 5. The degree and rate of fiber outgrowth was significantly enhanced by media containing gangliosides at a concentration of 10(-6), 10(-7) M when serum was left out and 10(-3), 10(-4) M when serum was added to the culture medium. The stimulating ganglioside action required the presence of NGF to induce neurite outgrowth. However, binding studies indicated that exogenous gangliosides do not affect NGF binding to PC12 cells, therefore their stimulatory action may be separated from the interaction between NGF and its receptors. Subculturing of NGF-treated cells for 10 days demonstrated that gangliosides treatment also enhanced the NGF stimulated regeneration of neurites. Gangliosides may be incorporated at the level of cell surface, thereby affecting and facilitating membrane phenomena involved in neurite outgrowth.

Kinetics of transfer of gangliosides from their micelles to dipalmitoylphosphatidylcholine vesicles

Two aspects of the kinetics of transfer of ganglioside from micelles to dipalmitoylphosphatidylcholine vesicles have been examined: (i) The first aspect is the rate of transfer of ganglioside from micelles at very low ganglioside/phospholipid ratios. Under these conditions the rate of incorporation into vesicles is independent of the vesicle concentration, indicating that transfer occurs by diffusion of ganglioside molecules through the aqueous phase and not by collision of micelles and vesicles. The initial transfer of monosialoganglioside is slower (t 1/2 = 2 h) than that of trisialoganglioside (t 1/2 = 0.5 h). The rate of transfer decreases during the transfer process. This decrease in rate depends on the character of the micelles and not on the ganglioside content of acceptor vesicles. The initial rate of transfer decreases sharply with decreasing temperature. (ii) The second aspect is the rate of transfer of ganglioside from micelles to phospholipid vesicles at high ganglioside/phospholipid ratios. In the presence of excess ganglioside, the level of incorporation into vesicles saturates when the ganglioside content of the vesicles reaches 12-15 mol %. This saturation level is not markedly dependent on the number of sialic acid residues in the ganglioside.