benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Ischemic-Attack--Transient

Omi/HtrA2 is a novel protein that contributes to the regulation of mitochondrial apoptosis after a variety of cell death stimuli in vitro and is thought to negatively control the inhibitor-of-apoptosis protein (IAP) family. However, the Omi/HtrA2 pathway remains unknown in apoptotic neuronal cell death in vivo. To examine the role of the Omi/HtrA2 pathway and its relationship to oxidative stress after reperfusion following cerebral ischemia, we used a transient focal cerebral ischemia (tFCI) model in copper/zinc-superoxide dismutase (SOD1) transgenic mice and wild-type mice. We evaluated the link between the Omi/HtrA2 pathway and the caspase cascade reaction after tFCI by administration of a pan-caspase inhibitor, Z-VAD-FMK. We observed the time-dependent expression of Omi/HtrA2 and its binding to X-chromosome-linked IAP (Omi/XIAP) by immunohistochemistry, Western blotting and coimmunoprecipitation. Translocation of Omi/HtrA2 into the cytosolic space was detected during the early period after tFCI and was not affected by Z-VAD-FMK administration, but it was prevented by SOD1 overexpression. Coimmunoprecipitation revealed that Omi/XIAP transiently increased and that it was prevented by SOD1 overexpression. These results suggest that the Omi/HtrA2 pathway may play an important role in the progress of apoptotic neuronal cell death and that overexpression of SOD1 may attenuate this apoptotic cell death by preventing the Omi/HtrA2 cell signaling pathway.

Topics: Amino Acid Chloromethyl Ketones; Animals; Blotting, Western; Brain; Caspase 3; Caspases; Cysteine Proteinase Inhibitors; Cytosol; Fluorescent Antibody Technique; High-Temperature Requirement A Serine Peptidase 2; Humans; Immunoprecipitation; Ischemic Attack, Transient; Male; Mice; Mice, Transgenic; Mitochondria; Mitochondrial Proteins; Nuclear Proteins; Oxygen; Phenanthridines; Proteins; Reperfusion; Serine Endopeptidases; Signal Transduction; Superoxide Dismutase; Superoxide Dismutase-1; Time Factors; X-Linked Inhibitor of Apoptosis Protein

Data reported in previous studies and our own previous experience have led us to explore the mechanism of and the degree of protection afforded by Ginko Biloba in a model of cerebral ischemia in the Mongolian Gerbil evaluating histological and neurological effects in this rodent.. Mongolian Gerbils were divided into experimental groups: Group A consisted of animals subjected only to experimental ischemia; 5 minutes occlusion of the carotid arteries. Group B consisted of animals subjected to experimental ischemia and to a dose of Ginko Biloba, given intraperitoneally immediately before the surgical procedure. Group C consisted of animals subjected to experimental ischemia and to a dose of Ginko Biloba, given intraperitoneally immediately after the surgical procedure. Group D consisted of animals subjected to experimental ischemia and to a dose of the caspase inhibitors z-VAD.FMK and z-DEVD.FMK injected intracerebroventricularly through the right hemisphere before the surgical procedure. Group E consisted of animals subjected to experimental ischemia and to a dose of caspase inhibitors injected after the surgical procedure. Group F consisted of Sham-operated animals. Histological controls were done by H and E and the TUNEL method in the frontal cortex and caudate-putamen.. The percentage of normal cells was not statistically significant at analysis with H and E, whereas the TUNEL method showed good protection with Ginko Biloba and caspase inhibitors, when the latter is given in the reperfusion phase. These data were in agreement with data obtained at neurological examination.. We could say that cellular morphology is in itself an untrustworthy tool for judging the effects of ischemia and protective drugs; the TUNEL method may add important information about the different components of cellular death; the reperfusion phase may be critical for apoptotic phenomena; Ginko Biloba might protect neurons of the frontal cortex from both necrotic and apoptotic death in this model of ischemia.

Topics: Amino Acid Chloromethyl Ketones; Animals; Caspase Inhibitors; Cerebral Cortex; Cysteine Proteinase Inhibitors; Drug Therapy, Combination; Gerbillinae; Ginkgo biloba; In Situ Nick-End Labeling; Ischemic Attack, Transient; Male; Neuroprotective Agents; Phytotherapy; Plant Preparations

The localization of caspase-1 protein, interleukin-1beta (IL-1beta)-converting enzyme, was immunohistochemically examined in the hippocampal CA-1 subfield by a transient occlusion of bilateral common carotid arteries in Mongolian gerbils. Immunoreactivities for caspase-1 were found in microglias, astrocytes, endothelial cells of capillaries and some non-pyramidal neurons. Immunopositive microglias increased in number from 3 days until 7 days from the transient ischemia, and astrocytes also increased in number from 3 days until 28 days. At the electron microscopic level, caspase-1 immunoreaction endproducts were associated with Golgi apparatus in glial cells, endothelial cells of blood vessels and non-pyramidal neurons. The delayed neuronal death of CA-1 pyramidal cells was significantly protected by the treatment of specific caspase-1 inhibitor (Ac-WEHD-CHO) or broad caspase family inhibitor (z-VAD-FMK). Cell death was protected in a dose dependent manner by the former by 43-57%, and by the latter by 66-91% when injected at 1 and 10 microg, respectively. On the other hand, the protective effect of specific caspase-3 inhibitor (Ac-DMQD-CHO) was less significant at higher dose (10 microg) by 33% (P<0.05), and not detectable at lower dose (1 microg) by 13% (P=0.27). Furthermore, a significant decrease of microglias and astrocytes was found in the CA-1 as well as the reduction of IL-1beta and caspase-1 immunoreactivities by the treatment of Ac-WEHD-CHO. Extravasation of serum albumin was also extremely reduced by this treatment. These findings suggest that the inhibition of caspase-1 activity ameliorates the ischemic injury by inhibiting the activity of IL-1beta.

Topics: Amino Acid Chloromethyl Ketones; Animals; Blotting, Western; Caspase 1; Caspase Inhibitors; Cell Death; Cell Survival; Enzyme Inhibitors; Gerbillinae; Hippocampus; Immunohistochemistry; Ischemic Attack, Transient; Male; Neurons; Oligopeptides

Recent studies have shown that release of mitochondrial cytochrome c is a critical step in the apoptosis process. We have reported that cytosolic redistribution of cytochrome c in vivo occurred after transient focal cerebral ischemia (FCI) in rats and preceded the peak of DNA fragmentation. Although the involvement of reactive oxygen species in the cytosolic redistribution of cytochrome c in vitro has been suggested, the detailed mechanism by which cytochrome c release is mediated in vivo has not yet been established. Also, the role of mitochondrial oxidative stress in cytochrome c release is unknown. These issues can be addressed using knock-out mutants that are deficient in the level of the mitochondrial antioxidant manganese superoxide dismutase (Mn-SOD). In this study we examined the subcellular distribution of the cytochrome c protein in both wild-type mice and heterozygous knock-outs of the Mn-SOD gene (Sod2 -/+) after permanent FCI, in which apoptosis is assumed to participate. Cytosolic cytochrome c was detected as early as 1 hr after ischemia, and correspondingly, mitochondrial cytochrome c showed a significant reduction 2 hr after ischemia (p < 0.01). Cytosolic accumulation of cytochrome c was significantly higher in Sod2 -/+ mice compared with wild-type animals (p < 0.05). N-benzyloxycarbonyl-val-ala-asp-fluoromethyl ketone (z-VAD.FMK), a nonselective caspase inhibitor, did not affect cytochrome c release after ischemia. A significant amount of DNA laddering was detected 24 hr after ischemia and increased in Sod2 -/+ mice. These data suggest that Mn-SOD blocks cytosolic release of cytochrome c and could thereby reduce apoptosis after permanent FCI.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Blood Pressure; Brain; Brain Ischemia; Cardiomyopathy, Dilated; Cerebral Cortex; Cerebral Infarction; Cysteine Proteinase Inhibitors; Cytochrome c Group; Cytosol; DNA Fragmentation; Heterozygote; Ischemic Attack, Transient; Male; Mice; Mice, Knockout; Mitochondria; Oxidative Stress; Rats; Superoxide Dismutase; Superoxides