title: Glutamate transporter type 3 mediates isoflurane preconditioning-induced acute phase of neuroprotection in mice.
abstract: A pre-exposure to isoflurane reduces ischemic brain injury in rodents (isoflurane preconditioning). This neuroprotection has acute and delayed phases. Our previous in vitro studies suggest that the acute phase may involve excitatory amino acid transporters (EAATs). We determine whether this protection involves EAAT3, the major neuronal EAAT. Adult male EAAT3 knockout mice and their wild-type littermates were exposed or were not exposed to 1.5% isoflurane for 30 min. Sixty minutes later, they were subjected to a 90- or 60-min middle cerebral arterial occlusion (MCAO). Their neurological outcomes were evaluated 24h after the MCAO. In another experiment, cerebral cortex was harvested for Western blotting at 30 min after animals were exposed to 1.5% isoflurane for 30 min. Here, we showed that isoflurane reduced brain infarct volumes and improved neurological functions of wild-type mice after a 90-min MCAO. However, isoflurane pre-exposure did not change the neurological outcome of EAAT3 knockout mice no matter whether the MCAO was for 90 min or 60 min. Isoflurane increased phospho-Akt, a survival-promoting protein, in the wild-type mice but not in the EAAT3 knockout mice. The isoflurane-induced neuroprotection in the wild-type mice was abolished by LY294004, an Akt activation inhibitor. LY294004 alone did not affect the neurological outcome of the wild-type or EAAT3 knockout mice after focal brain ischemia. These results suggest that the isoflurane preconditioning-induced acute phase of neuroprotection involves EAAT3. The downstream event includes Akt activation.
authors.affiliation: Department of Anesthesiology, University of Virginia, Charlottesville, VA, United States.
authors.forename: Liaoliao
authors.initials: L
authors.lastname: Li
authors.forename: Jiao
authors.initials: J
authors.lastname: Deng
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Zuo
mesh_terms: D000818:Animals; D020520:Brain Infarction / Q000209:etiology / Q000517:prevention & control; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000494:pharmacology; D050580:Excitatory Amino Acid Transporter 3 / Q000172:deficiency / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D020244:Infarction, Middle Cerebral Artery / Q000150:complications / Q000517:prevention & control*; D007530:Isoflurane / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D051058:Oncogene Protein v-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: D004791:Enzyme Inhibitors; D050580:Excitatory Amino Acid Transporter 3; D018696:Neuroprotective Agents; C493399:Slc1a1 protein, mouse; D007530:Isoflurane; D051058:Oncogene Protein v-akt
keywords: Akt; EAAT; ERK1/2; GAPDH; GSK3β; Glutamate transporter; Isoflurane; MCAO; Neuroprotection; Preconditioning; SpO(2); excitatory amino acid transporter; extracellular signal-regulated kinase 1/2; glyceraldehyde 3-phosphate dehydrogenase; glycogen synthase kinase 3β; middle cerebral arterial occlusion; pulse oximeter oxygen saturation