dizocilpine-maleate and Hemolysis

A growing body of experimental evidence suggests that an intracerebral hematoma is toxic to neighboring cells. However, injury mechanisms remain largely undefined, due in part to conflicting results from in vivo studies. In order to investigate blood toxicity in a more controlled environment, murine clots were co-cultured on porous membrane inserts with primary neurons and glia. Erythrocyte lysis was apparent within 48 h, but was reduced by almost 80% in cultures lacking neurons, and by over 90% in the absence of both neurons and glial cells. By 72 h, most released hemoglobin had oxidized to methemoglobin or its hemichrome degradation products. At this time point, approximately 50% of neurons were non-viable, as detected by propidium iodide staining; glia were not injured. Deferoxamine, Trolox and the NMDA receptor antagonist MK-801 prevented most neuronal death, but had no effect on hemolysis at neuroprotective concentrations. The 27-fold increase in culture malondialdehyde and 5.8-fold increase in heme oxygenase-1 expression were also attenuated by deferoxamine and Trolox, but not by MK-801. These results suggest that hemoglobin release from clotted blood is accelerated by adjacent neurons and glia. Subsequent neurotoxicity is mediated by both iron-dependent and excitotoxic injury pathways.

Topics: Animals; Cell Death; Cells, Cultured; Coculture Techniques; Dizocilpine Maleate; Hematoma, Subdural, Chronic; Heme Oxygenase-1; Hemoglobins; Hemolysis; Iron; Malondialdehyde; Mice; Neuroglia; Neurons; Neurotoxins; Time Factors

The concentrations of GABA, glutamate, aspartate, glycine, taurine, glutamine, asparagine and alanine were determined in the CSF of 10 Senegalese baboons (Papio papio) following initial ketamine anaesthesia and subsequent administration (4 h later) of different compounds known to alter either inhibitory or excitatory neurotransmission. Ketamine itself was apparently without effect as the administration of a second dose of ketamine did not significantly alter the levels of any of the amino acids studied, although GABA levels tended to decrease. The presence of haemolysed material in occasional samples was associated with high GABA, glutamate, aspartate, taurine and asparagine levels. Therefore only haemolysate-free samples were included for analysis. Of the compounds administered, gamma-vinyl GABA had the most evident effect on CSF amino acid levels, increasing GABA (greater than 5-fold) and decreasing glutamate (greater than 50%), aspartate (40-50%), asparagine (20%) and alanine (30-35%) levels. The changes in GABA, glutamate and aspartate were still apparent 24 h post-gamma-vinyl GABA administration. In contrast, sodium valproate did not significantly alter the CSF levels of any of the amino acids studied. Upon acute administration allylglycine decreased the CSF concentrations of GABA and alanine, but not glutamate. These alterations are unlikely related to the occurrence of allylglycine-induced convulsions (in 2 of 4 experiments) as electroconvulsive shock did not alter CSF amino acid levels. During the experimental period encompassing the allylglycine injection (8 weeks), basal (initial post-ketamine, pre-drug sample) amino acid levels were abnormal with large increases in glutamate, GABA, aspartate and taurine whereas asparagine levels were below the limit of detection. Diazepam administration was followed by a significant increase in taurine and a decrease in aspartate levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Amino Acids; Animals; Diazepam; Dizocilpine Maleate; Electroshock; Hemolysis; Humans; Ketamine; Neurotransmitter Agents; Papio; Phencyclidine; Reference Values; Valproic Acid