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

The role of the monosialoganglioside, GM1 as a neuroprotectant in an experimental model of cardiopulmonary bypass and hypothermic circulatory arrest

Twelve male dogs were placed on closed-chest cardiopulmonary bypass, subjected to 2 h of HCA at 18 degrees C, and rewarmed to 37 degrees C on closed-chest cardiopulmonary bypass. All animals were mechanically ventilated and monitored for 20 h before extubation and survived for 3 days. Group 1 dogs (n = 6) were pretreated with GM1, 30 mg/kg/24 h for 3 days before HCA, and received continuous infusion of GM1 during the procedure and 30 mg/kg/24 h for 3 days after HCA. Group 2 dogs (n = 6) received vehicle only. With a species-specific behavior scale that yielded a neurodeficit score ranging from 0% (normal) to 100% (brain dead), all animals were neurologically assessed every 12 h by two observers. After death at 72 h, brains were examined by glutamate receptor autoradiography and by histologic examination for patterns of selective neuronal necrosis and were scored blindly from 0 (normal) to 100 (severe injury). These results provide evidence of a role for GE in the development of HCA-induced brain injury and suggest that monosialogangliosides may have a neuroprotective effect in prolonged periods of HCA.

Effects of GM1 ganglioside on cardiac function following experimental hypoxia-reoxygenation

Rat hearts made hypoxic for 20 min by perfusion with 95% N2/5% CO2 and reoxygenated for 20 min in a Langerdorff apparatus showed a dose-dependent reduction of lactate dehydrogenase release when incubated with ganglioside GM1 (0.1-10 microM). The decline of contractile force during hypoxia was also reduced dose dependently in the presence of GM1. Similar effects were observed in hearts obtained from animals treated i.p. with 40 mg/kg GM1 for 14 days. The levels of Na+,K(+)-ATPase in ventricular tissue were also reduced after hypoxia-reoxygenation and the reduction was prevented in hearts from GM1-treated animals. GM1 (1-30 microM) reduced the functional response to field stimulation of adrenergic nerve terminals in isolated atria. Rat atria made hypoxic in glucose-free media maintained normal stores of tissue noradrenaline in the presence of 1 microM GM1. In the rabbit, GM1 (40 mg/kg i.p. for 4 days) reduced the alterations of the ST segment of the ECG during acute occlusion of the left descending and circumflex coronaries artery. In conclusion, ganglioside GM1 reduces some effects of hypoxia-reoxygenation in the heart, through still unknown mechanisms.

Current concepts in cerebral protection

In the past, physicians viewed ischemic injury as an irreversible event. Modern science has shown that this view is incorrect and that ischemic neuronal damage is an ongoing, active process that might be amenable to various therapies. Figure 2 illustrates some of the possible sites where these therapies might be active. Pending evidence of their effectiveness, cerebral protection can best be achieved by maintaining adequate CPP and CBF during periods when patients are at risk for cerebral ischemia, restoring perfusion after ischemia occurs, and optimizing the metabolic milieu of the ischemic penumbra.

Temporal changes in edema, Na+, K+, and Ca++ in focal cortical stroke: GM1 ganglioside reduces ischemic injury

Cortical focal ischemia in the rat was induced by middle cerebral artery occlusion (MCAo) together with permanent occlusion of the ipsilateral common carotid artery (CCAo) and a temporary (1 hr) occlusion of the contralateral CCA. By using a defined cortical tissue sampling procedure at 3, 6, 24, 72, 96, and 120 hr after the MCAo + CCAo, patterns of edema and ion (Na+, K+, and Ca++) changes in a primary and three peri-ischemic cortical areas are described. Ionic imbalances and edema formation have distinct patterns, are time dependent, and are different when comparing primary and peri-ischemic areas. Calcium increases to "neurotoxic" levels appear temporally independent of edema formation, reaching magnitudes 20 times greater than basal levels in the primary infarct area. Na+ increases correlate with increases in water, while K+ losses do not appear to be directly related to edema formation of Na+ and Ca++ increases. K+ losses are only significant in the primary infarct area. Rats treated with GM1 ganglioside (10 mg/kg, i.m.) daily showed significant reductions in edema, Na+ and Ca++ increases. These ganglioside effects were evident as early as 24 hr after the ischemic injury. Ca++ increases, which was maximal at 72 hr after the ischemic injury, was reduced by greater than 50% in GM1-treated animals. The mechanism by which GM1 is an effective neuroprotective agent may be evidenced by its effects on Ca++ influx/efflux processes in injury.

Protective effect of gangliosides on myocardial hypoxic damage in the rat

The size of the infarct produced by ligation of the left coronary artery in the rat was decreased significantly in animals treated i.p. with 40 mg/kg per day of a ganglioside mixture (GMIX) for 7 days after surgery. Rats treated with GMIX had lower ventricular myeloperoxidase activity, indicating a lower leukocyte infiltration after infarction. The underperfused zone was also smaller in animals treated daily with GMIX 30 days after surgery. Control hearts, but not hearts obtained from animals pretreated for 15 days with 40 mg/kg per day of GMIX, released lactate dehydrogenase (LDH) during perfusion in a Langerdorff apparatus after ligation and reperfusion of the left coronary artery in vitro. Hearts made hypoxic in vitro by changing the perfusion gas to nitrogen for 20 min and later reoxygenating with 95% O2 -5% CO2 released LDH in the perfusate, but did not do so in the presence of 10 microM monosialotetraesosylganglioside. Gangliosides, therefore, seem to protect the rat heart against hypoxic damage.

Gangliosides: the relevance of current research to neurosurgery

Gangliosides are complex glycolipids found on the outer surface of most cell membranes: they are particularly concentrated in tissues of the nervous system. Gangliosides form part of the immunological identity of mammalian cells and are involved in a variety of cell-surface phenomena such as cell-substrate binding and receptor functions. In tumorous tissue, the ganglioside composition is altered, sometimes in direct proportion to the degree of malignancy. The literature on the glycosphingolipid composition and immunology of intracranial tumors is reviewed. Some gangliosides induce neuritogenesis and exhibit a trophic effect on nerve cells grown in vitro. In vivo, a particular ganglioside, GM1, reduces cerebral edema and accelerates recovery from injury (traumatic and ischemic) to the peripheral and central nervous systems of laboratory animals. Preliminary clinical studies have shown that treatment with gangliosides may have corresponding effects on lesions of the human peripheral nervous system. Gangliosides have not been tested in human subjects with brain injury.

Gangliosides prevent ischemia-induced down-regulation of protein kinase C in fetal rat brain

Complete obstruction of the maternal blood flow to fetal rats at 20 days of gestation for a period of 10 min causes a significant shift of approximately 22% in protein kinase C (PKC) activity from a cytosolic to a membrane-bound form in the fetal brain. This translocation can be entirely reversed without losses in activity by a single intraperitoneal injection into the gravid rat of either a mixture of disialo- and trisialoganglioside [polysialoganglioside (PSG)] or by GM1 (50 mg/kg of body weight) given 3 h before onset of the ischemic episode. Cessation of blood flow for 15 min followed by a reperfusion period of 24 h results in a 47% loss in total PKC activity. This down-regulation can be almost entirely prevented upon intraperitoneal administration of GM1 3 h before, but also during and even 90 min after the onset of ischemia. The PSG mixture is also effective, particularly when given 3 h before the insult. Down-regulation of PKC is accompanied by an increase in a Ca2(+)-phosphatidylserine-independent kinase [protein kinase M (PKM)] activity, which rises from 30 pmol/min/mg of protein in control animals to a maximal value of 83.1 pmol/min/mg of protein after 15 min of ischemia and 6 h of reperfusion. By 24 h, PKM activity is 46.8 pmol/min/mg of protein. Administration of GM1 blocks completely the appearance of PKM, a result suggesting that PKC down-regulation and PKM activity elevation are intimately associated events and that both are regulated by GM1 ganglioside.

GM1 ganglioside reduces cognitive dysfunction after focal cortical ischemia

The functional consequences of cortical focal ischemia and the effect of monosialoganglioside (GM1) treatment on learning/performance of a spatial reversal task were investigated. Cortical focal ischemia was induced by a permanent occlusion of the left common carotid artery and the ipsilateral middle cerebral artery, with a 1-h clamping of the contralateral carotid artery. Twenty-six rats were randomly assigned to three groups: sham controls, a saline-treated ischemic group, and a GM1 ganglioside-treated ischemic group (10 mg/kg/day: IM). Fifteen days after surgery rats were trained on a spatial reversal task in a two-lever operant chamber where food reward was contingent on lever pressing. Training continued from day 15 to day 21 after surgery. Cortical focal ischemia resulted in learning/performance deficits that were reduced by GM1 ganglioside treatment. The cognitive deficits were characterized by a significantly higher number of nonperseverative errors and number of responses to criterion. There was a significant difference between left and right lever performance in the saline-treated ischemic group, which was absent in shams and GM1-treated ischemic rats. On all measures GM1-treated rats were not different from sham controls.

Excitatory amino acid neurotoxicity in cultured retinal neurons: involvement of N-methyl-D-aspartate (NMDA) and non-NMDA receptors and effect of ganglioside GM1

Cultures of chicken day 8 embryo retinal cells, essentially free of contaminating non-neuronal elements, were used to examine the neurotoxicity of various excitatory amino acid transmitter receptor agonists. At 7 days in vitro, N-methyl-D-aspartate (NMDA), following 24 hr exposure to 0.1-1.0 mM, destroyed 60-70% of the multipolar neurons, but apparently spared photoreceptors. The cytotoxic effect of NMDA was prevented by extracellular Mg2+ or phencyclidine, suggesting a role for the NMDA ion channel; competitive NMDA antagonists were also neuroprotective. The mixed excitatory amino acid receptor agonist glutamate (0.1-1.0 mM) was also neurotoxic (approximately 70% loss of multipolar neurons) and strongly blocked by NMDA (but weakly by non-NMDA) antagonists and Mg2+, indicating a major action at NMDA receptors. As with NMDA, glutamate did not appear to affect photoreceptors. The neurotoxic action of kainate against multipolar retinal neurons, as reported by others, was confirmed here. Kainate neuronal injury was sensitive to the quinoxalinedione non-NMDA antagonists 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyanoquinoxaline-2,3-dione (CNQX), but not to Mg2+ or phencyclidine. Ibotenate and quisqualate, even at millimolar concentrations, were not neurotoxic. The monosialoganglioside GM1 was also effective in reducing NMDA and non-NMDA agonist neurotoxicity to retinal neurons. Maximal ganglioside benefit required 1-2 hr of pretreatment with 100-200 microM GM1. The percentage of multipolar neurons remaining after the neurotoxin insult approximately doubled with GM1 treatment. Gangliosides may thus have a therapeutic potential in excitatory amino acid-initiated neuropathologies.

Hypoglycemic neurotoxicity in vitro: involvement of excitatory amino acid receptors and attenuation by monosialoganglioside GM1

Rat cerebellar granule cells, when subjected to a glucose-free environment for 4 h, developed extensive degeneration of neuronal cell bodies and their associated neurite network over the following 24 h. This neuronal damage was quantitated with a colorimetric assay using the metabolic dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. Hypoglycemic neuronal injury could be markedly reduced by the presence of both competitive (3-(+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid) and non-competitive (phencyclidine) N-methyl-D-aspartate receptor antagonists, but not by kainate/quisqualate preferring antagonists 6-cyano-7-nitroquinoxaline-2,3-dione and 6,7-dinitroquinoxaline-2,3-dione. Glucose deprivation neuronal injury was also reduced by adding glutamate-degrading enzymes to the incubation medium. Monosialoganglioside GM1, but not its asialo derivative (lacking sialic acid), was also effective in protecting against hypoglycemic neurodegeneration when included during the period of glucose deprivation. These results suggest that the neuronal injury to cerebellar granule cells resulting from glucose deprivation is mediated predominantly by activation of the N-methyl-D-aspartate type of excitatory amino acid receptor, perhaps through the action of endogenously released glutamate. Furthermore, the monosialoganglioside GM1, a member of a class of naturally occurring sialoglycosphingolipids, is able to attenuate this neuronal injury--as already observed for glutamate neurotoxicity and anoxic neuronal death in cerebellar granule cells. Gangliosides may thus prove to be of therapeutic utility in excitatory amino acid-associated neuropathologies.

GM1 ganglioside treatment after global ischemia protects changes in membrane fatty acids and properties of Na+, K+-ATPase and Mg2+-ATPase

An examination was made of the effects of ganglioside GM1 (i.m.) on the losses of membrane fatty acids (palmitic, stearic, oleic, linoleic, and arachidonic), the plasma membrane enzyme Na+, K+-ATPase, and the mitochondrial membrane enzyme Mg2+-ATPase, associated with global ischemia 24 hr after permanent unilateral occlusion of the carotid artery in Mongolian gerbils. While there was a significant loss of fatty acids in saline controls, no loss was detected in membranes from GM1-injected gerbils. Rather, we found an increase in membrane fatty acid content, indicative of altered turnover. A 38% loss of Na+, K+-ATPase and a 36% loss of mitochondrial Mg2+-ATPase observed in membranes from saline controls was reduced in membranes from GM1-injected animals to losses of 15% and 8% respectively. These effects are further described by analyses of enzyme kinetics (apparent Vmax and apparent Km). After 1 week of storage, the activities of both membrane ATPases from saline controls decreased substantially more than from GM1-injected animals, suggesting that the GM1 membranes were better "preserved." Since there was a minimal loss in protein content after 24 hr of ischemia, these results indicate that systemically injected GM1 may protect structure and function of plama membranes during the acute phases of ischemic injury.