Na(+)-dependent chloride transporter (NKCC1)-null mice exhibit less gray and white matter damage after focal cerebral ischemia.
We previously demonstrated that pharmacological inhibition of Na(+)-K(+)-Cl- cotransporter isoform 1 (NKCC1) is neuroprotective in in vivo and in vitro ischemic models. In this study, we investigated whether genetic ablation of NKCC1 provides neuroprotection after ischemia. Focal ischemia was induced by 2 hours occlusion of the left middle cerebral artery (MCAO) followed by 10 or 24 hours reperfusion. Two hours MCAO and ten or twenty-four hours reperfusion caused infarction (approximately 85 mm3) in NKCC1 wild-type (NKCC1(+/+)) mice. Infarction volume in NKCC1(-/-) mice was reduced by approximately 30% to 46%. Heterozygous mutant (NKCC1(+/-)) mice showed approximately 28% reduction in infarction (P>0.05). Two hours MCAO and twenty-four hours reperfusion led to a significant increase in brain edema in NKCC1(+/+) mice. In contrast, NKCC1(+/-) and NKCC1(-/-) mice exhibited approximately 50% less edema (P<0.05). Moreover, white matter damage was assessed by immunostaining of amyloid precursor protein (APP). An increase in APP was detected in NKCC1(+/+) mice after 2 hours MCAO and 10 hours reperfusion. However, NKCC1(-/-) mice exhibited significantly less APP accumulation (P<0.05). Oxygen-glucose deprivation (OGD) induced approximately 67% cell death and a fourfold increase in Na+ accumulation in cultured NKCC1(+/+) cortical neurons. OGD-mediated cell death and Na+ influx were significantly reduced in NKCC1(-/-) neurons (P<0.05). In addition, inhibition of NKCC1 by bumetanide resulted in similar protection in NKCC1(+/+) neurons and astrocytes (P<0.05). These results imply that stimulation of NKCC1 activity is important in ischemic neuronal damage.
Chen
Hai
H
Neuroscience Training Program, University of Wisconsin Medical School, Madison, Wisconsin 53792, USA.
Luo
Jing
J
Kintner
Douglas B
DB
Shull
Gary E
GE
Sun
Dandan
D
D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000378:metabolism* / Q000473:pathology; D001929:Brain Edema / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020520:Brain Infarction / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002545:Brain Ischemia / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002034:Bumetanide / Q000008:administration & dosage; D016923:Cell Death; D004232:Diuretics / Q000008:administration & dosage; D005947:Glucose / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D019579:Neocortex / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D015427:Reperfusion Injury / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012964:Sodium / Q000378:metabolism; D028021:Sodium-Potassium-Chloride Symporters / Q000235:genetics / Q000378:metabolism*; D064506:Solute Carrier Family 12, Member 2
D016564:Amyloid beta-Protein Precursor; D004232:Diuretics; C578878:Slc12a2 protein, mouse; D028021:Sodium-Potassium-Chloride Symporters; D064506:Solute Carrier Family 12, Member 2; D002034:Bumetanide; D012964:Sodium; D005947:Glucose