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

Developmental change in ganglioside expression in primary culture of rat neurons

Developmental changes in ganglioside levels and patterns were investigated in neuronal cells dissociated from 17-day-old fetal rat hemispheres for up to 7 days of culture. Increases in ganglioside contents and the onset of GM3 synthesis, which is associated with proliferation of glial cells, were observed as the neuronal network was established in cell cultures. The distribution of gangliosides in developing neurons was monitored by the indirect immunofluorescent technique using three anti-ganglioside antibodies. Anti-GM1 antibody showed immunofluorescence only on the cell soma 1 and 3 days after plating and additional binding between cell aggregates by 7 days in culture. GD3 ganglioside, the predominant species in embryonic neurons, was not detected on the neuronal cell surface, whereas the number of positively stained non-neuronal cells was increased at 7 days. Monoclonal A2B5 antibody suggested that polysialogangliosides play a role in neuronal network formation. In 1-day-old culture, however, all antibodies bound poorly to cell surface antigens and strongly to cells, the membranes of which were permeabilized with acetone. These results suggest that a substantial amount of gangliosides are retained, transformed within the cell to more complex gangliosides, and translocated to the cell surface following neurite outgrowth and morphological changes.

Cografts of adrenal medulla with peripheral nerve enhance the survivability of transplanted adrenal chromaffin cells and recovery of the host nigrostriatal dopaminergic system in MPTP-treated young adult mice

Schwann cells from transected peripheral nerve segments are known to produce nerve growth factor (NGF). We performed adrenal medullary grafts or cografts of adrenal medulla and sciatic nerve into the striatum of MPTP-treated young adult mice, and compared the survivability of grafted chromaffin cells and the recovery of intrinsic host DA fibers using computerized image analysis of tyrosine hydroxylase (TH)-immunoreactive (IR) fibers and neurochemical analysis with high performance liquid chromatography (HPLC). Adrenal medullary chromaffin cells cografted with sciatic nerve survived better than those in adrenal grafts alone; host DA fiber recovery was more prominent in mice with cografts than in mice with adrenal grafts alone. A large number of TH-IR surviving cells in cografted mice showed long neuronal processes which were rarely seen in the mice receiving adrenal graft alone. We conclude that cograft of adrenal medulla and sciatic nerve promotes intrinsic host DA fiber recovery better than adrenal medulla grafts alone, and that survivability of grafted chromaffin cell may promote host DA fiber recovery. Adrenal medullary autografts have been used in patients with Parkinson's disease; we suggest that if this approach is to be used in the future, methods to increase the survivability of grafted chromaffin cells, such as co-grafting with pieces of peripheral nerve, be considered to enhance the survivability of the chromaffin cells, which might be closely related to the functional recovery of the patients by this grafting procedure. Of course, such strategies as the present cografting approach must be demonstrated to work in older animals using older donor tissue before proceeding to this next step in humans.

Solubilization of the membrane-bound sialidase from pig brain by treatment with bacterial phosphatidylinositol phospholipase C

The total pellet from pig forebrain (from which the cytosolic sialidase was completely washed out) was treated with phosphatidylinositol phospholipase C (PIPLC) and centrifuged at high speed. The supernatant contained sialidase and 5'-nucleotidase activities. The greatest liberation of sialidase was obtained after incubation for 20 min with PIPLC at 37 degrees C using pH 6.0 and a ratio between PIPLC (as units) and protein of 1.6. Under these conditions, the release of sialidase, 5'-nucleotidase, and protein was 22, 50, and 18.5%, respectively. On treatment with PIPLC, a purified preparation of pig brain neuronal (synaptosomal) membranes released 28% of its sialidase whereas a purified preparation of pig brain lysosomes did not liberate any sialidase activity. The pH optimum of sialidase present in the supernatant obtained after PIPLC treatment of the total pellet was 4.2, the same as that of the enzyme embedded in the membrane. When this supernatant was subjected to ammonium sulfate fractionation, 88% of its sialidase, having a pH optimum of 4.2, was recovered in the fraction precipitated between 20 and 45% of salt saturation and subsequently dialyzed. Ammonium sulfate treatment caused the appearance of a second sialidase activity, having a pH optimum of 6.6 and behaving on fractionation similarly to the pH 4.2 sialidase. The Km and Vmax values of pH 4.2 and pH 6.6 sialidase were similar (1.48 x 10(-4) and 0.98 x 10(-4) M for Km and 1.6 and 1.4 mU/mg of protein for Vmax, respectively), whereas the stability on standing at 4 degrees C or exposure to freezing and thawing cycles was greater for pH 4.2 sialidase.(ABSTRACT TRUNCATED AT 250 WORDS)

GM1 gangliosides alter acute MPTP-induced behavioral and neurochemical toxicity in mice

We investigated the effect of GM1 gangliosides on a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) animal model of Parkinson disease. Five groups of mice (saline, GM1 (30 mg/kg), MPTP, MPTP + GM1 (15 mg/kg), MPTP + GM1 (30 mg/kg] were compared. GM1 was given daily via intraperitoneal injection before and during 13 daily doses of MPTP (30 mg/kg). Mice were tested for locomotion (1) within 2 h of an MPTP dose (to measure reduced motor activity), and (2) within 24 h of an MPTP dose (after animals had recovered and exhibited hyperactivity). We found that mice given GM1 gangliosides exhibited significantly less MPTP-induced behavior. This effect was most evident with the 15 mg/kg GM1 dose. GM1 also appeared to attenuate MPTP-induced neurochemical changes. GM1 effects indicating enhancement of DA turnover and preservation of DA, DOPAC and HVA concentrations in the striatum were found after the 8th MPTP dose. These latter neurochemical changes, however, were transient and not present after the 13th MPTP dose. Our data would suggest that gangliosides may reduce acute MPTP-induced neurotoxicity in mice either through an increase in DA neuron survival and/or the augmentation of striatal DA activity.

Synaptic membrane complex carbohydrates in experimental hepatic encephalopathy

To evaluate further the status of synaptic plasma membranes (SPMs) in the brain in the syndrome of hepatic encephalopathy (HE) lipid- and protein-bound sialic acid and ganglioside and protein composition were investigated in SPMs from the brains of six rabbits with galactosamine-induced fulminant hepatic failure and five normal rabbits. HE was associated with no appreciable changes in the chromatographic pattern of gangliosides or the concentration of protein-bound sialic acid, but the syndrome was associated with a 20% increase in lipid-bound sialic acid and, as assessed electrophoretically, an increase in the concentration of a protein with a molecular weight of about 70 kDa. Thus, changes in the composition of complex carbohydrates and protein in SPMs occur in a model of HE. The findings raise the possibility that nonhumoral factors, such as increased sialylation of glycolipids, contribute to the generation of abnormal neurotransmission in HE.

Critical review of gangliosides and thyrotropin-releasing hormone in peripheral neuromuscular diseases

The lack of effective therapy for many of the chronic neuromuscular diseases such as amyotrophic lateral sclerosis, hereditary motor sensory neuropathy (Charcot-Marie-Tooth disease), spinocerebellar degenerations and idiopathic polyneuropathy has led to a search for substances that may stimulate peripheral nerve regeneration. Two such agents that have been proposed are gangliosides (mixed purified bovine brain gangliosides, Cronassial) and thyrotropin releasing factor (TRH). Studies on both of these agents were initially reported with enthusiasm to be successful, but later double-blind controlled studies have failed to confirm these findings. This review provides critical analysis of the designs of studies of potentially effective agents in chronic neuromuscular diseases, and emphasizes the power of the placebo response, and the importance of designing placebos which are indistinguishable from the trial medication other than in the active effect.

Impaired nerve regeneration in streptozotocin-diabetic rats is improved by treatment with gangliosides

The rate of sciatic nerve regeneration and the effect of ganglioside treatment thereon were studied in the streptozotocin-diabetic rat. Two experimental protocols were used. In the first, sciatic nerves were crushed at 3 weeks of diabetes and treatment with purified bovine brain gangliosides (10 mg/kg/day ip) was begun the day before crush. In the second, nerves were crushed at 5 weeks of diabetes and treatment was started 7 days before crush. Regeneration was evaluated in both cases with the pinch-reflex test at different time points after crush. In either situation untreated diabetic rats showed a decreased rate of regeneration when compared to untreated nondiabetic rats, with a more severe reduction in 5-week diabetic rats. Ganglioside treatment improved regeneration in the second protocol; untreated diabetic rats had regenerated 10.6 +/- 0.9 mm (mean +/- SEM) at 7 days postcrush, while nerves from ganglioside-treated and control rats had regenerated 16.4 +/- 1.1 and 20.3 +/- 1.0 mm, respectively (n = 9-11, P less than 0.001 for untreated vs ganglioside-treated diabetics with two-way ANOVA). Ganglioside treatment did not alter the rate of regeneration in nondiabetic rats.

Effect of gangliosides on membrane permeability studied by enzymic and fluorescence-spectroscopy techniques

The effect of gangliosides on membrane permeability was investigated by studying the kinetic properties of cytochrome c oxidase, the activity of which, when the enzyme is reconstituted in phospholipid vesicles, is dependent on membrane permeability to H+ and K+. The experiments indicate that three different gangliosides (GM1, DD1a, GT1b) incorporated into cytochrome c oxidase-containing phospholipid vesicles stimulate enzymic activity, in the absence of ionophores, most probably by disorganizing the bilayer lipid assembly and increasing its permeability to ions. This interpretation was confirmed by fluorescence-spectroscopy experiments in which the rate of passive leakage of carboxyfluorescein entrapped in the vesicles was measured. Cholera toxin, or its isolated B-subunit, added to GM1-containing proteoliposomes inhibited cytochrome c oxidase activity, indicating the lack of formation, under these experimental conditions, of channels freely permeable to H+ or K+.

Effect of monosialoganglioside (GM1) on transected monoaminergic pathways

The effects of exogenous monosialogangliosides (GM1) on transected monoaminergic cerebral cortical pathways were investigated in mice. Norepinephrine (NE), 5-hydroxytryptamine (5-HT), and 5-hydroxyindole-3-acetic acid (5-HIAA) contents were determined in cerebral cortex rostral and caudal to unilateral coronal transection sites. The transmitter contents were expressed as a ratio of those in the unlesioned contralateral cortex. In the caudal cortex, NE ratios fell to 70% within a week after transection and decreased further to 35-40% by 4 weeks. Treatment with exogenous GM1 for 2 weeks starting shortly after the lesion increased NE concentrations in the caudal cortex to 47.4-55.0% at 4 weeks, significantly greater than control animals (p less than 0.01, Mann-Whitney U-test). GM1 treatment for 2 and 4 weeks, starting 2 weeks after the lesion, yielded similar results. The 5-HT and 5-HIAA ratios in the caudal cortex also rose significantly after GM1 treatment. Thus, GM1 increased monoaminergic levels nonspecifically in the cortex caudal to the cortical lesion. The treatment effect did not depend on the timing or duration of treatment. These results indicate that exogenous GM1 treatment has a nonspecific restorative effect on the central nervous system after axonal lesions.

Regulation of Ca2+/calmodulin-dependent protein kinase II by brain gangliosides

Purified rat brain Ca2+/calmodulin-dependent protein kinase II (CaM-kinase II) is stimulated by brain gangliosides to a level of about 30% the activity obtained in the presence of Ca2+/calmodulin (CaM). Of the various gangliosides tested, GT1b was the most potent, giving half-maximal activation at 25 microM. Gangliosides GD1a and GM1 also gave activation, but asialo-GM1 was without effect. Activation was rapid and did not require calcium. The same gangliosides also stimulated the autophosphorylation of CaM-kinase II on serine residues, but did not produce the Ca2+-independent form of the kinase. Ganglioside stimulation of CaM-kinase II was also present in rat brain synaptic membrane fractions. Higher concentrations (125-250 microM) of GT1b, GD1a, and GM1 also inhibited CaM-kinase II activity. This inhibition appears to be substrate-directed, as the extent of inhibition is very dependent on the substrate used. The molecular mechanism of the stimulatory effect of gangliosides was further investigated using a synthetic peptide (CaMK 281-309), which contains the CaM-binding, inhibitory, and autophosphorylation domains of CaM-kinase II. Using purified brain CaM-kinase II in which these regulatory domains were removed by limited proteolysis. CaMK 281-309 strongly inhibited kinase activity (IC50 = 0.2 microM). GT1b completely reversed this inhibition, but did not stimulate phosphorylation of the peptide on threonine-286. These results demonstrate that GT1b can partially mimic the effects of Ca2+/CaM on native CaM-kinase II and on peptide CaMK 281-309.

Exogenous GM1 gangliosides induce partial recovery of the nigrostriatal dopaminergic system in MPTP-treated young mice but not in aging mice

The administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to young (2-3 months) and aging (12 months) C57BL/6 mice (4 x 20 mg/kg, i.p., given 12 h apart) reduced tyrosine hydroxylase (TH)-immunoreactive (IR) fibers in the striatum, and reduced dopamine (DA) concentration to 28% of controls in young, and 16% of controls in aging mouse brain five weeks after administration. Although GM1 ganglioside treatment (30 mg/kg, i.p., daily for 5 weeks) restored striatal dopamine concentration to 74% of the control concentration in young mice, such an apparent recovery was not seen in aging brain. Immunocytochemical analysis also showed marked recovery of TH-IR fibers in the striatum of MPTP-depleted young mice treated with GM1 ganglioside while TH-IR fibers in the striatum of MPTP-depleted aging mice showed no recovery with such treatment. We conclude that treatment of MPTP-depleted young mice with GM1 ganglioside results in partial recovery in the striatal DA system, but such benefits do not extend to aging mice.

Maternal alcohol consumption and undernutrition in the rat: effects on gangliosides and their catabolizing enzymes in the CNS of the newborn

Consumption of fifteen percent alcohol, during gestation did not cause any decrease in the total calorie or fluid intake of the rats maintained on normal dietary regimen. However, the alcohol consumption by gestating mothers resulted in a decreased contents of both DNA and protein in the CNS of the in utero alcohol exposed pups at birth. DNA content was also found to be less in the undernourished pups compared to the normal pups. On the other hand an increase in the total gangliosides and a decrease in the ganglioside catabolizing enzymes was observed in the brain and spinal cord of alcoholic pups at birth. However undernutrition resulted in a decrease in the content of total gangliosides both in brain and spinal cord. Maternal alcohol consumption and undernutrition had also resulted in an altered proportions of the individual ganglioside fractions.

Sialidase in cerebellar granule cells differentiating in culture

The optimal conditions for the assay of sialidase in cerebellar granule cells cultivated in vitro, established using [3H]GD1a and 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid (MUB-NeuNAc) as substrates, were the following: pH optimum for both substrates, 3.9; optimal molarity of sodium acetate/acetic acid buffer, 0.05 M with [3H]GD1a and 0.1 M for MUB-NeuNAc; substrate concentration for apparent maximal activity, 0.5 mM for MUB-NeuNAc and 0.1 mM for [3H]GD1a; enzyme activity linear with time up to 30 min with MUB-NeuNAc and up to 90 min with [3H]GD1a; and enzyme activity linear with enzyme protein content up to 80 micrograms with MUB-NeuNAc and up to 20 micrograms with [3H]GD1a. The assay with [3H]GD1a required the presence of Triton X-100 in a molar ratio to GD1a of 15:1. Poly-L-lysine, which was used for plating the cells, was capable of decreasing sialidase activity against [3H]GD1a/Triton X-100 when added to the incubation mixture. However, it had no effect on the enzyme working on MUB-NeuNAc. Using no more than 20 micrograms of cellular protein, the contamination, if any, by poly-L-lysine released from the dish was below the concentration limit exhibiting inhibition. Using the above optimal conditions, sialidase activity was measured during cerebellar granule cell differentiation in culture. From day 0 to day 7-8 in culture, the enzyme activity rose from 20 to 130 nmol of product released/h/mg of protein with MUB-NeuNAc and from 1 to 100 nmol of product released/h/mg of protein with [3H]GD1a.(ABSTRACT TRUNCATED AT 250 WORDS)

Glutamate transport and not glutamate receptor binding is stimulated by gangliosides in a Ca2+-dependent manner in rat brain synaptic plasma membranes

Crude as well as purified synaptic plasma membrane (SPM) preparations were analyzed for the influence of the ganglioside galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosylgluc osyl ceramide (GM1) on high-affinity binding of L-[3H]glutamate. Assayed in two different buffer systems, SPM consistently exhibited increased (40-50%) binding upon incubation with GM1 plus Ca2+, as compared to controls without GM1. Incorporation experiments with 3H-labeled GM1 proved trypsin-stable insertion of GM1 into SPM, with a maximum incorporation of four times the endogenous amount (35 nmol/mg of protein). The observed increase in glutamate binding was not due to a change in the affinity of the binding sites, but to a change in the number of binding sites, and it was absolutely dependent on the presence of Ca2+. A pharmacological profile of the GM1/Ca2+-stimulated glutamate binding is presented. The original classification of the stimulatory effect as an effect on glutamate receptor binding had to be revised to take into account the observed temperature sensitivity of the ganglioside effect, its sensitivity to high osmolarity and to ultrasonication, and the lack of binding stimulation after detergent treatment of membranes or after receptor solubilization. Vesicular space measured in both SPM preparations was found to be around 7 microliters/mg of protein, in ganglioside-treated as well as in control membranes. From the data, it is concluded that a special, Na+- and Cl- -independent form of glutamate transport into resealed membrane vesicles is stimulated by gangliosides in the presence of Ca2+.

Amyotrophic lateral sclerosis: an unconventional autoimmune disease?

The possibility of an autoimmune mechanism of pathogenesis in amyotrophic lateral sclerosis has long been considered, but the evidence to support a conventional autoimmune process, reviewed here, is inconclusive. However, antibodies that react in vitro with gangliosides have recently been found in sera of a large majority of patients with classical amyotrophic lateral sclerosis and other motor neuron syndromes. A working hypothesis is proposed, suggesting how antibodies might be related to the disease process. The hypothesis attempts to account for (1) a pathogenic role of antibodies directed against the carbohydrate components of glycolipids, (2) the selectivity of the process for motor neurons, (3) an antibody-mediated mechanism that could result in apparently degenerative neuropathological changes without signs of inflammation, and (4) a type of autoimmune response that is extremely difficult to suppress by conventional means. Although the evidence for this hypothesis is by no means complete, its critical features are all testable.

Topography of monosialoganglioside (GM1) in rat brain using monoclonal antibodies

Immunohistochemical localization of ganglioside GM1 using 3 monoclonal antibodies (C3 and D3 reacting exclusively with GM1 and C4h2 reacting also with other gangliosides) showed different staining patterns in rat brain regions (cerebellum, cerebral cortex and hippocampus). Staining in all brain areas was punctate and appeared to be restricted to surfaces of cells and their processes. In spite of similar reactivity to GM1, C3 and D3 showed qualitatively and quantitatively different and highly selective localization in all regions with no staining in white matter. In cerebellum, staining with C3 was predominantly associated with granular layer; staining with D3 was limited to Purkinje cell surfaces and surrounding structures. In cortex, staining with C3 was seen outlining large pyramidal neurons and fibers in cross-section, whereas sites stained with D3 appeared to be fewer, smaller and differed in location. In hippocampus, staining patterns were similar with both C3 and D3, outlining large pyramidal neurons of Ammon's horn and granular cells of dentate gyrus as well as glomerular structures. Staining with C4h2 was topographically similar, but over 10-fold more extensive and was present in white matter.

Influence of monosialoganglioside inner ester on neurologic recovery after global cerebral ischemia in monkeys

We assessed the consequences of transitory global cerebral ischemia and the influence of monosialoganglioside inner ester (AGF 2) treatment on neurologic outcome, cerebral blood flow, and cerebral metabolic rate in monkeys over 48 hours. Global cerebral ischemia was produced by a cervical tourniquet and a lowering of blood pressure to 6.65 kPa; recirculation followed after 30 minutes. AGF 2 (30 mg/kg) was administered intravenously immediately after initiation of recirculation and intramuscularly twice a day for 48 hours. Our results show that treatment with AGF 2 significantly accelerated the rate of neurologic recovery. Improvement was evident 5 hours after ischemia; full neurologic recovery was observed in half of the monkeys 48 hours after ischemia. This recovery was associated with a less severe reduction in cerebral blood flow without a concomitant increase in the cerebral metabolic rate.

Therapeutic strategies in promoting peripheral nerve regeneration

Currently, regeneration chambers, adrenocorticotropic hormone (ACTH) and related peptides, and gangliosides appear to be the most promising therapies in the promotion of peripheral nerve regeneration, growth, and repair. Regeneration chambers enhance rat sciatic nerve regeneration in vivo after transection by providing a structurally organized and protected preformed space within which nerve fibers are exposed to macromolecular compounds which direct and enhance nerve growth. ACTH and related peptides, independent of their corticotropic activities, increase the availability of structural proteins to the axon terminal in rats subjected to nerve crush injuries and demonstrate inotropic effects in adrenalectomized and/or hypophysectomized rats. Exogenously administered gangliosides promote neuronal sprouting, regeneration, and reinnervation in experimental situations and have undergone clinical testing in acute and chronic peripheral nerve disorders. At the current dosage levels and schedules, the clinical results of ganglioside therapy have been mixed. The success of the experimental studies supports further clinical testing of these therapies in peripheral nerve disorders.

Acrylamide-induced increases in deposition of axonally transported glycoproteins in rat sciatic nerve

The axonal transport of proteins, glycoproteins, and gangliosides in sensory neurons of the sciatic nerve was examined in adult rats exposed to acrylamide via intraperitoneal injection (40 mg/kg of body weight/day for nine consecutive days). The L5 dorsal root ganglion was injected with either [35S]methionine to label proteins or [3H]glucosamine to label, more specifically, glycoproteins and gangliosides. At times ranging from 2 to 6 h later, the sciatic nerve and injected ganglion were excised and radioactivity in consecutive 5-mm segments determined. In both control and acrylamide-treated animals, outflow profiles of [35S]methionine-labeled proteins showed a well defined crest which moved down the nerve at a rate of approximately 340 mm/day. Similar outflow profiles and transport rates were seen for [3H]glucosamine-labeled glycoproteins in control animals. However, in animals treated with acrylamide, the crest of transported labeled glycoprotein was severely attenuated as it moved down the nerve. This finding suggests that in acrylamide-treated animals, axonally transported glycoproteins were preferentially transferred (unloaded or exchanged against unlabeled molecules) from the transport vector to stationary axonal structures. We also examined the clearance of axonally transported glycoproteins distal to a ligature on the nerve. The observed impairment of clearance in acrylamide-treated animals relative to controls is supportive of the above hypothesis. Acrylamide may directly affect the mechanism by which axonally transported material is unloaded from the transport vector. Alternatively, the increased rate of unloading might reflect an acrylamide-induced increase in the demand for axonally transported material.

Ganglioside composition of synaptic vesicles from Torpedo electric organ

We have studied the ganglioside content and pattern of synaptic vesicles isolated from the electric organs of two species of Torpedinidae, Torpedo californica and Torpedo marmorata. The ganglioside concentrations were high relative to protein content (77 and 58 micrograms of N-acetylneuraminic acid/mg of protein, respectively), owing to the low protein-to-lipid ratio; however, they were also appreciable in relation to phospholipid (15.6 and 10.0 micrograms of N-acetylneuraminic acid/mg of phospholipid). The fact that a membrane fraction that separated from synaptic vesicles of T. californica on a controlled-pore glass-bead column and constituted the main potential source of contamination in this preparation had a lower ganglioside content and a different TLC pattern than synaptic vesicles indicated the relatively high purity of the latter. Most of the gangliosides from synaptic vesicles of both species migrated on TLC in the vicinity of standards with three or more sialic acids. Synaptosomes from T. marmorata had a higher lipid N-acetylneuraminic acid/phospholipid ratio and a different TLC pattern than synaptic vesicles. Considering these results and other data appearing recently in the literature, we suggest that reexamination of synaptic vesicles from mammalian brain for the possible presence of gangliosides is warranted.

Solubilized glycosyltransferases and biosynthesis in vitro of glycolipids

The assembly of most of the ceramide-linked glycolipids (GSLs) in eukaryotic cells occurs in Golgi bodies. At least 18 different glycolipid:glycosyltransferases (GSL:GLTs) have been characterized, 10 of which have been solubilized. These GLTs can be classified into 2 distinct groups: 1) GLTs dedicated to either Dol-P-P-sugar(s) or ceramide-linked sugar(s); and 2) GLTs with dual loyalties (i.e., they compete with glycolipid- and glycoprotein-bound oligosaccharides). Studies with solubilized and purified GalNAcT-1 and GalNAcT-2 from embryonic chicken brains prove that GalNAcT-1 (UDP-GalNAc:GM3 beta 1-4GalNAcT) is specific for GSL, whereas GalNAcT-2 (UDP-GalNAc:Gb3 beta 1-3GalNAcT) can transfer to an oligosaccharide containing the alpha-linked terminal galactose. Similarly, GalT-3 (UDP-Gal:GM2 beta 1-3GalT) is more specific for ganglio-oligosaccharide and GalT-4 (UDP-Gal:Lc3 beta 1-4GalT) can transfer galactose to N-acetylglucosamine linked to p-nitrophenol, glycolipid or glycoprotein. Both GalT-3 and GalT-4 have been separated and purified from embryonic chicken brains. Studies with solubilized SAT-4 and SAT-3, from bovine spleen and embryonic chicken brains, respectively, suggest the existence of 2 different gene-expressed alpha 2-3SATs. The newly discovered FucT-3 (GDP-Fuc:NeuGc-iLc6-alpha 1-3FucT) from human colon carcinoma (Colo-205) has also been solubilized and separated from other GSL:GLTs. Using a new activity gel-Western blot combined technique, the molecular mass of this FucT-3 was determined to be 105 kDa.

Treatment with GM1 ganglioside restores striatal dopamine in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mouse

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 30 mg/kg i.p. daily for 7 days, was administered to mice. This dosage regimen resulted in an approximately 50% reduction of striatal dopamine (DA) level. Chronic administration of GM1 ganglioside (II3NeuAc-GgOse Cer), beginning between 1 to 4 days after terminating MPTP dosing, resulted in partial restoration of the striatal DA level. From dose- and time-response studies, it appeared that 30 mg/kg i.p. of GM1 administered daily for approximately 23 days resulted in an approximately 80% restoration of the DA level and complete restoration of the 3,4-dihydroxyphenylacetic acid (DOPAC) content. This dosage of GM1 also restored the turnover rate of DA in the striatum to near normal. Discontinuing GM1 treatment resulted in a fall of DA and DOPAC levels to values found in mice treated with MPTP alone. There was no evidence for regeneration of nerve terminal amine reuptake in the GM1-treated mice as evaluated by DA uptake into synaptosomes. Our biochemical findings in animals suggest that early GM1 ganglioside treatment of individuals with degenerative diseases of dopaminergic nigrostriatal neurons might be fruitful.

Gangliosides of cultured astroglia

Cultured astrocytes prepared from newborn rat brain and 13-day-old chick embryonic brain were analyzed qualitatively and quantitatively for ganglioside content. All preparations contained approximately the same total level: 2.4-3.4 micrograms N-acetylneuraminic acid (NeuAc)/mg protein. In contrast, the value for primary cultures of neurons from chick embryonic brain was 5.9. The non-hexosamine-containing species, GM3 and GD3, comprised 75-85% of the total in astroglial cultures, the remainder consisting mainly of structural types other than the gangliotetraose series; choleragenoid assay revealed the latter to be virtually absent or to comprise at most a few percent. Deficiency of gangliotetraose synthesizing ability was indicated by the very low level of UDP-GalNac:GM3 N-acetylgalactosaminyltransferase detected in the cells. Treatment of cultured astrocytes with astroglial growth factor 2 or dibutyryl cyclic AMP caused little if any change in quantity or pattern of gangliosides. The large majority of cells stained in a manner characteristic of astrocytes: positive for glial fibrillary acidic protein, negative for galactosyl ceramides. Staining with cholera toxin and anti-GM1 antibody was essentially negative, as was that with tetanus toxin, A2B5 monoclonal antibody, and antibody to GD3. All evidence thus points to cultured astrocytes of rat and chick brain containing appreciable gangliosides, most of which are GM3 and GD3 with the majority of the remainder comprising structures other than the gangliotetraose type.

Ganglioside content of astroglia and neurons isolated from maturing rat brain: consideration of the source of astroglial gangliosides

Previous biochemical and histochemical studies have failed to clarify the nature or quantity of gangliosides in CNS astrocytes. Using improved methodologies for bulk isolation of both neurons and astrocytes as well as for ganglioside purification, we find significantly higher ganglioside concentration in astrocytes and very similar thin-layer chromatography (TLC) patterns for the two cell types. However, in vivo labeling of glycoconjugates via intracerebral injection of [3H]glucosamine prior to cell isolation revealed a different picture: whereas glycoproteins were well-labeled in both cell types after labeling periods of 1-2 h, gangliosides were appreciably labeled only in neurons. With longer time periods (8-48 h) between injection and sacrifice, there was convergence of specific radioactivity of gangliosides from the two isolated cell preparations. These changes are compared to those observed in synaptosomes and microsomes that were isolated simultaneously. The results suggest limited ganglioside synthetic ability in astrocytes as compared to neurons, a conclusion supported by assay of UDP-galNAc:GM3 N-acetylgalactosaminyltransferase in the isolated cells. Nevertheless, the presence of ganglioside GM1 in a substantial portion of bulk-isolated astrocytes was demonstrated by indirect immunofluorescent detection of cholera toxin binding. Ideas on the reconciliation of these apparently contradictory phenomena, including the possibility of intercellular transfer and/or phagocytosis are discussed.

Dendritic ramifications of trigeminal motor neurons innervating jaw-closing muscles of rats

A cholera toxin subunit conjugated horseradish peroxidase (CTHRP) was found to be very useful in labelling the dendrites of motoneurons. CTHRP was injected individually to jaw-closing muscles (temporalis, masseter, and medial pterygoid) of rats, and their motoneurons including the dendrites were labelled and studied. The results show that the motoneuron cell bodies innervating temporalis, masseter, and medial pterygoid muscles are located in the trigeminal motor nucleus in dorsal, ventromedial and ventrolateral position. The dendrites of these motoneurons extend radially into mesencephalic nucleus, supratrigeminal nucleus, pontine reticular formation, trigeminal sensory nucleus and even into the bundles of the ascending root of the facial nerve. These dendrites may serve as an extended surface for various synaptic contacts to the jaw closing motoneurons. The possibility that they may also have presynaptic influence on the input to the trigeminal motoneurons is also discussed.

Effect of the ganglioside GM1 on neurologic function, electroencephalogram amplitude, and histology in chronic middle cerebral artery occlusion in cats

The effect of the ganglioside GM1 on amplitude of the electroencephalogram, neurologic function, and histology has been studied in chronic middle cerebral artery occlusion in cats. Ischemia was produced by a 2-hour occlusion of the left middle cerebral artery and was followed by a 7-day observation period. GM1 was intravenously administered 30 minutes after occlusion and daily during the observation period. Using the reduction in the electroencephalogram amplitude to measure stroke severity, three cats with mild, three cats with moderate, and three cats with severe stroke were treated with 5 mg/kg GM1. Nine cats, three in each group, were treated with 30 mg/kg GM1, while nine cats, three in each group, received middle cerebral artery occlusion but no treatment. In all cats there was a precipitous fall in mean electroencephalogram amplitude during occlusion, followed by a secondary fall during the observation period. Treated cats showed better recovery of electroencephalogram amplitude during the first 4 hours of reperfusion and a smaller secondary fall than untreated cats. Treated cats, especially those treated with 5 mg/kg GM1, showed significant recovery of neurologic deficits compared with untreated cats. Histologic damage was less in treated cats than in untreated cats. Some cats treated with 30 mg/kg GM1 exhibited convulsions, whereas no untreated cat showed any seizure activity. Our findings suggest that gangliosides may improve the recovery of both neurologic deficits and morphologic damage in the central nervous system. These positive effects might be tentatively explained by stimulation of enzymatic activities such as Na+, K+-ATPase and adenyl cyclase.

Phospholipid asymmetry in renal brush-border membranes

The topological distribution of phospholipids between the inside and the outside of rabbit kidney brush-border membranes has been investigated by incubating membrane vesicles with sphingomyelinase, phospholipases A2 from bee venom and hog pancreas, phospholipases C and D, and trinitrobenzene sulfonate. Orientation and integrity of vesicles upon phospholipase treatment was determined by using two monoclonal antibodies recognizing an extracytoplasmic and a cytoplasmic domain, respectively, of the neutral endopeptidase (EC 3.4.24.11). It is shown that the transbilayer distribution of phospholipids is highly asymmetrical in kidney brush-border membranes: sphingomyelin accounted for 75% of the phospholipids present in the external leaflet, whereas phosphatidylethanolamine and phosphatidylserine plus phosphatidylinositol were found to comprise the majority of the inner layer of the membrane.

Gangliosides and other lipids of the growth cone membrane

Growth cone membranes, derived from growth cone particles isolated from 16- to 18-day-old fetal rat brain, were found to be rich in overall lipid content with a lipid-to-protein ratio of 3.5. The phospholipid-to-cholesterol ratio indicated considerably less cholesterol than plasma membranes from mature neurons. All major classes of phospholipid were present in the usual proportions except sphingomyelin, which could not be detected. Gangliosides expressed in relation to protein were present at somewhat higher levels compared to previously reported values for synaptic plasma membranes (73 versus 44 micrograms/mg protein), but when related to phospholipid their level was well below that of the latter (26 versus 62 micrograms/mg phospholipid). The ganglioside pattern was generally similar to that of mature synaptic membranes except for the presence of relatively more GD3 and less GD1a, a phenomenon also observed in whole fetal brain of the same age. Several neutral glycosphingolipids were detected, glucosylceramide being the major one of this group. Their total level in growth cone membranes was roughly comparable to that of gangliosides, but unlike the latter their concentration in whole brain decreased with development. For comparison we analyzed the ganglioside composition of mixed membrane fractions from the same fetal brains and found no significant differences between these and growth cone membranes, suggesting that these glycoconjugates are not localized specifically in the growth cones. Neutral glycosphingolipids, on the other hand, appeared somewhat more concentrated in growth cones than in the mixed membranes.

Axonal transport of intraocularly injected [3H-Sph]-GD1a in the chicken optic system and the fate of the exogenous ganglioside distributed by blood

Twelve-day-old chicks (White Leghorn) received an injection of 481 kBq (8.1 nmol) of [3H-Sph]-GD1a, which was labeled in its sphingoid, into the right eye. Structures of the injected and the non-injected (control) optic system (retinae, optic nerves, chiasm, optic lobes), the cerebrum, blood liver, kidney, and fly-muscle were analyzed 1, 4, 8 and 14 days later, with respect to total non-volatile radioactivity and to that bound to lower-phase lipids and gangliosides. It was demonstrated that exogenous [3H-Sph]-GD1a was taken up by the retina and mainly catabolized. 3H-label, reincorporated into the lower-phase lipids and gangliosides as well as authentic exogenous [3H-Sph]-GD1a were transported rapidly anterogradely in the entire optic system. [3H-Sph]-GD1a, distributed via the blood stream, was taken up by liver, kidney and muscle and was metabolized faster in these organs than in the retina. The cerebrum and the brain structures of the control optic system incorporated 3H-radioactivity to a much lower extent than the non-neural organs.

A role for gangliosides in astroglial cell differentiation in vitro

Rat cerebral astroglial cells in culture display specific morphological and biochemical behaviors in response to exogenously added gangliosides. To examine a potential function for endogenous gangliosides in the processes of astroglial cell differentiation, we have used the B subunit of cholera toxin as a ganglioside-specific probe. The B subunit, which is multivalent and binds specifically to GM1 ganglioside on the cell surface, induced a classical star-shaped (stellate) morphology in the astroglial cells and inhibited DNA synthesis in a dose-dependent manner. The morphological response was massive and complete within 2 h, with an ED50 of 0.8 nM, and appeared to depend on the direct interaction of the B subunit with GM1 on the cell surface. A B subunit-evoked inhibition of DNA synthesis and cell division (ED50 = 0.2 nM) was observed when the cells were stimulated with defined mitogens, such as epidermal growth factor and basic fibroblast growth factor. Maximal inhibition approached 80% within 24 h. The effects of the B subunit were unrelated to increases in cAMP. These observations, taken together with previous studies, demonstrate that both endogenously occurring plasma membrane gangliosides and exogenously supplied gangliosides can influence the differentiative state (as judged by morphological and growth behaviors) of astroglial cells in vitro.

Biosynthesis and expression of gangliosides during differentiation of chick embryo retina cells in vitro

Cells from neural retina from 7-day chick embryos were cultured on polylysine-coated dishes up to 7 days. The small, round-shaped cells at seeding differentiated progressively, and after 4 days in vitro the majority had enlarged bodies and abundant processes. The content of protein and DNA was essentially unchanged during the entire period of culture. The incorporation of radioactivity from [3H]glucosamine into gangliosides declined slightly, reaching about 65% of the initial values at the end of the culture period. The proliferating activity measured by the incorporation of [3H]thymidine into DNA decreased to 10% or less of the initial value after 3 days in vitro. Almost at the same chronological times as in ovo, the synthesis of GD3 and of a ganglioside partially identified as GT3 decreased from 70 and 19% of the total incorporation into gangliosides in the first 20 h of culture to about 7 and 5%, respectively, after 3 days in vitro. Conversely, the synthesis of GD1a increased from about 6% at the beginning to about 70% at the end of the culture times. Immunocytochemical analyses of the expression of gangliotetraosyl gangliosides in cultured cells showed that these gangliosides appeared in the bodies and processes of cells having neuronal morphology; very little immunostaining of the scarce flattened cells, probably Müller cells, was found. The results indicate that the changes in ganglioside metabolism, which lead to decreased synthesis of gangliosides lacking the galactosyl-N-acetyl-galactosaminyl disaccharide end and to increased synthesis of gangliotetraosyl gangliosides, occur in cells that in culture differentiate into neurons.

The GM1 ganglioside hastens the reduction of hyperemotionality after septal lesions

The purpose of the present study was to assess the effects of ganglioside treatment on changes in emotional, activity, and avoidance behaviors following septal brain damage. Rats were treated with GM1-gangliosides either before and after septal lesions, or only after septal lesions and tested for emotionality on 10 consecutive days beginning on the second day after surgery. The ganglioside treatment decreased the emotionality of rats with septal damage on the first test day, and enhanced their rate of recovery to control levels of emotionality. Septal rats treated with gangliosides had activity, rearing, and avoidance behaviors equivalent to nontreated septal rats; however, lesioned rats treated with GM1 showed reduced intertrial crossings during avoidance conditioning. These results suggest that the changes in emotional behavior of septal rats treated with GM1 occur shortly after the lesion.

Effect of exogenous gangliosides on amino acid uptake and Na+, K+-ATPase activity in superior cervical and nodose ganglia of rats

The effects of some gangliosides on active uptake of nonmetabolizable alpha-aminoisobutyric acid (AIB) and Na+, K+-ATPase and Ca2+, Mg2+-ATPase activities in superior cervical ganglia (SCG) and nodose ganglia (NG) excised from adult rats were examined during aerobic incubation at 37 degrees C for 2 h. In NG, amino acid uptake was greatly accelerated with the addition of galactosyl-N-acetylgalactosaminyl-[N-acetylneuraminyl]-galactosylgluc osyl ceramide (GM1) (85%) and also with N-acetylgalactosaminyl-[N-acetylneuraminyl]-galactosylglucosyl ceramide (GM2) or [N-acetylneuraminyl]-galactosyl-N-acetylgalactosaminyl-[N-acetyl- neuraminyl]-galactosylglucosyl ceramide (GD1a) (43% each) compared with a nonaddition control at a 5 nM concentration. Under identical conditions, Na+, K+-ATPase activity was strongly stimulated with GM1 (180%) and GD1a (93%), whereas Ca2+, Mg2+-ATPase activity showed no change. In SCG, on the other hand, AIB uptake was apparently inhibited (-27%) by addition of GM1, with a slight decrease in Na+, K+-ATPase but no change in Ca2+, Mg2+-ATPase activity in the tissue. Both asialo-GM1, in which N-acetylneuraminic acid is deficient, and Forssman glycolipid, which is not present in nervous tissue, failed to produce any significant increase in both SCG and NG not only in amino acid uptake, but also in Na+, K+-ATPase activity. A kinetic study of active AIB uptake showed that GM1 ganglioside produced an increase in Km with no change in Vmax in SCG, whereas it caused a decrease in Km with a slight increase in Vmax in NG. Treatment of NG and SCG with neuraminidase from Vibrio cholerae, an enzyme that split off sialic acid from polysialoganglioside, leaving GM1 intact, caused little inhibition of the amino acid uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Dendritic organization of phrenic motoneurons in the adult rat

The dendritic organization of the phrenic nucleus as a whole was studied after injections of the B-subunit of cholera toxin conjugated to horseradish peroxidase were made into the diaphragm of adult rats. Transverse, sagittal, and horizontal sections through the phrenic nucleus (C3-C5) were incubated according to a modified tetramethylbenzidine HRP technique. The conjugated form of HRP used in this study has a special affinity for the GM1 ganglioside receptors on neuronal cell surfaces. As a result, extensive labeling of the terminal dendritic fields of a large number of phrenic motoneurons occurred simultaneously. The results showed that the majority of the dendrites of phrenic motoneurons were tightly organized rostrocaudally and confined to the boundaries of the column made up of the phrenic cell bodies. In addition, analysis of transverse and horizontal sections revealed dendritic bundles radiating at right angles to the long axis of the cell column in the following directions: dorsolateral into the dorsal half of the lateral funiculus, lateral into the lateral funiculus, ventromedial into the lateral half of the anterior funiculus, ventrolateral into the ventral half of the lateral funiculus, and dorsal into the intermediate gray matter. Some dendritic bundles were measured as far as 900 microns from phrenic cell bodies into the white matter. The horizontal sections also showed that there was a periodicity in the arrangement of the dendritic fascicles in that they were separated by distances ranging from 180 to 250 microns. From the analysis of phrenic dendritic distribution the present results suggest that the majority of synaptic input to phrenic motoneurons occurs within the column of the phrenic cell bodies. In addition, there is evidence to suggest that a synaptic input may also occur directly on distal phrenic dendrites in the lateral and ventral funiculi of the spinal cord white matter.

Axonal transport characteristics of gangliosides in sensory axons of rat sciatic nerve

The distribution of axonally transported gangliosides and glycoproteins along the sciatic nerve was examined from 3 h to 4 weeks following injection of[3H]glucosamine into the fifth lumbar dorsal root ganglion of adult rats. Incorporation of labeled precursor into these glycoconjugates reached a maximal level in the ganglion within 6 h. Outflow patterns of radioactivity for glycoproteins showed a well-defined crest with a transport rate of approximately 330 mm/day. In contrast, the crest of transported gangliosides was continuously attenuated, implying a significant deposition along the axon, and an alternative method of calculating velocity was required. Analysis of accumulation of labeled material at double ligatures demonstrated both anterograde and retrograde transport of glycoproteins and gangliosides and allowed for the calculation of an anterograde transport rate of about 270 mm/day for each. Additional evidence of ganglioside transport is provided in that the TLC pattern of transported radioactive gangliosides accumulating at a ligature is significantly different from the pattern seen in the dorsal root ganglion or following intraneural administration of the labeled precursor. These data indicate that gangliosides are transported at the same rapid rate as glycoproteins but are subject to a more extensive exchange with stationary material than are glycoproteins.

Fluorescent properties of merocyanine 540 in solutions of sialogangliosides

The spectral modifications in the absorption and emission properties of merocyanine 540 have been evaluated in solvents of varying dielectric constants. The fluorescence behavior of dye in solutions of low dielectric constant has offered a possibility for monitoring the micropolarity of sialoganglioside micelles in aqueous solutions. Our results demonstrate that sialic acid residues markedly influence the aggregation properties of gangliosides in solution as well as the nature of dye binding to the micellar structures.

Parenterally administered GM1 ganglioside prevents retrograde degeneration of cholinergic cells of the rat basal forebrain

The effect of daily intraperitoneal injections of GM1 ganglioside on retrograde degeneration in the basal forebrain has been examined, using a monoclonal antibody directed against choline acetyltransferase to identify the cholinergic neurones. Rats underwent extensive damage of the cerebral cortex and underlying hippocampus. From the day of operation on, they received daily injections of ganglioside. After a survival of 30 days, the animals were killed and the cholinergic cells of the basal forebrain were examined. These were compared with material treated in the same way from animals who had received the injections of ganglioside but no lesion, animals who had been operated upon but without the ganglioside treatment, and normal animals. Intraperitoneal ganglioside administration markedly reduces the retrograde death of the cholinergic neurones of the medial septal nucleus and abolishes the shrinkage of the remaining neurones following hippocampal damage.

Complex glycosphingolipids of the pheochromocytoma cell line PC12: enhanced fucosylglycolipid synthesis following nerve growth factor treatment

The effect of nerve growth factor treatment on the expression of neutral glycosphingolipids and gangliosides was examined in PC12 pheochromocytoma cells grown in spinner culture. These studies show that PC12 cells contain an unusual group of fucose containing neutral glycolipids and gangliosides. The fucose containing neutral glycolipids, which appear to be derivatives of globoside, are very minor components. However, nearly all of the gangliosides in PC12 cells contain fucose. Two minor neutral glycolipids were isolated from these cells, and were identified as fucosylgloboside and galactosylgloboside. Two major gangliosides were also isolated and identified as fucosyl GM2 and fucosyl GD2. Studies using [3H]fucose to examine the synthesis of fucosylglycolipids indicate that nerve growth factor enhances the incorporation of fucose into glycolipids and gangliosides by as much as 80%. These studies show that all of the gangliosides in PC12 cells appear to increase in concentration when the cells are treated with nerve growth factor in spinner culture. However, only the complex fucose containing neutral glycolipids increase in concentration during this same treatment, while the non-fucosylated precursors do not.

Rapid adhesion of nerve cells to muscle fibers from adult rats is mediated by a sialic acid-binding receptor

Single viable muscle fibers isolated from adult rats by collagenase digestion rapidly bind dissociated spinal neurons or PC-12 cells but not a variety of other cells tested. The adhesion process is calcium-independent, temperature-sensitive, and is not blocked by pretreating cells with inhibitors of energy metabolism or actin polymerization. Adhesion is mediated by a carbohydrate-binding protein and can be inhibited by N-acetylneuraminic acid or mucin, a glycoprotein with high sialic acids content. The hapten inhibitors do not dissociate cells if added after aggregation has occurred. Experiments to block adhesion by pretreatment of cells with either neuraminidase or mucin show that the sialic acids-rich moiety is on the nerve cells, while its receptor is on the muscle fibers.