Neuroprotective Role of Transgenic PAF-Acetylhydrolase II in Mouse Models of Focal Cerebral Ischemia

Abstract

Background and Purpose-Platelet-activating factor (PAF) and oxidized unsaturated free fatty acids have been postulated to aggravate neuronal damage in the postischemic brain. Type II PAF-acetylhydrolase (PAF-AH II) not only terminates signals by PAF by its PAF-hydrolyzing activity but also protects cells against oxidative stress. We examined whether PAF-AH II can rescue cerebral neurons against ischemic insults. Methods-Transgenic mice overexpressing human PAF-AH II in neurons were generated and enzyme expressions were examined biochemically and histochemically. The mice were subjected to 60 minutes of transient middle cerebral artery occlusion followed by reperfusion for 24 hours. The infarction and apoptosis were estimated by TTC staining and fluorescence TUNEL staining, respectively. Results-Overexpression of PAF-AH II was found in brains of transgenic mice by Western blot and enzymatic activity analyses. In immunohistochemistry, human PAF-AH II expression was found throughout the central nervous system, especially in neurons of neocortex, hippocampus, and basal ganglia. The neurological deficit scores, cerebral edema index, and relative infarction volume were all significantly (PϽ0.05) lower in transgenic mice (1.30Ϯ0.72, 1.12Ϯ0.04, and 14.0Ϯ7.7%, respectively) than in wild-type mice (2.56Ϯ0.93, 1.23Ϯ0.12, and 31.9Ϯ9.7%, respectively). Percentages of apoptotic cells were also significantly (PϽ0.001) lower in transgenic mice (cortex, 5.2Ϯ3.3%; hippocampus, 3.4Ϯ7.0%) than in wild-type mice (cortex, 41.1Ϯ16.9%; hippocampus, 58.9Ϯ15.3%). Conclusions-These results indicate that PAF-AH II exerts strong neuroprotective effects against ischemic injury and suggest a possibility for clinical use of this enzyme in cerebral ischemia.

Protection against Oxidative Stress-induced Hepatic Injury by Intracellular Type II Platelet-activating Factor Acetylhydrolase by Metabolism of Oxidized Phospholipids in Vivo

“…7A), indicating that PAF-AH (II) protects against CCl 4 -induced hepatic injury mainly in the later phase in contrast to vitamin E. Although the mechanism underlying these processes is not known, the accumulation of oxidized phospholipids in cells may delay the recovery from oxidative stress-induced tissue injury. We have recently reported that transgenic mice expressing PAF-AH (II) under the control of a neuron-specific promoter are highly resistant to reperfusion injury after focal cerebral ischemia, in which oxidative stress is thought to be involved (63). These results, taken together with the present results, indicate that PAF-AH (II) plays a protective role in oxidative stress-induced tissue injury in vivo.…”

Suppression of Mitochondrial Function by Oxidatively Truncated Phospholipids Is Reversible, Aided by Bid, and Suppressed by Bcl-XL

“…This is a critical protective mechanism against exogenous oxidized phospholipids, tert-butyl hydroperoxide oxidative stress, or Ca 2ϩ overloading of neuronal cells because overexpression of PAF acetylhydrolase protects cells from all these apoptotic insults (13,16,34,62,63). This means that for these oxidative insults it is the intact oxidized phospholipid that is responsible for the apoptotic event.…”

Mutation-, Aging-, and Gene Dosage-dependent Accumulation of Neuroserpin (G392E) in Endoplasmic Reticula and Lysosomes of Neurons in Transgenic Mice

“…Generation of Transgenic Mice-DNA solution (3 ng/l) was microinjected into the pronuclei of fertilized eggs from BDF1 females as described (21). Identification of transgenic mice was performed by PCR on tail genomic DNA; the sequences of the primers for transgene amplification were 5Ј-CCA GGT TCA CAG TGG AAC AG-3Ј and 5Ј-ATA CAG CAC AGC CAT CCT AC-3Ј.…”