Atorvastatin upregulates type III nitric oxide synthase in thrombocytes, decreases platelet activation, and protects from cerebral ischemia in normocholesterolemic mice.
OBJECTIVE
Thrombosis superimposed on atherosclerosis causes approximately two thirds of all brain infarctions. We previously demonstrated that statins protect from cerebral ischemia by upregulation of endothelial type III nitric oxide synthase (eNOS), but the downstream mechanisms have not been determined. Therefore, we investigated whether antithrombotic effects contribute to stroke protection by statins.


METHODS
129/SV wild-type and eNOS knockout mice were treated with atorvastatin for 14 days (0.5, 1, and 10 mg/kg). eNOS mRNA from aortas and platelets was measured by reverse-transcriptase polymerase chain reaction. Platelet factor 4 (PF 4) and beta-thromboglobulin (beta-TG) in the plasma were quantified by ELISA. Transient cerebral ischemia was induced by filamentous occlusion of the middle cerebral artery followed by reperfusion.


RESULTS
Stroke volume after 1-hour middle cerebral artery occlusion/23-hour reperfusion was significantly reduced by 38% in atorvastatin-treated animals (10 mg/kg) compared with controls. Serum cholesterol levels were not affected by the treatment. eNOS mRNA was significantly upregulated in a dose-dependent manner in aortas and in thrombocytes of statin-treated mice compared with controls. Moreover, indices of platelet activation in vivo, ie, plasma levels of PF 4 and beta-TG, were dose-dependently downregulated in the treatment group. Surprisingly, atorvastatin-treatment did not influence PF 4 and beta-TG levels in eNOS knockout mice.


CONCLUSIONS
The synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin upregulates eNOS in thrombocytes, decreases platelet activation in vivo, and protects from cerebral ischemia in normocholesterolemic mice. Antithrombotic and stroke-protective effects of statins are mediated in part by eNOS upregulation. Our results suggest that statins may provide a novel prophylactic treatment strategy independent of serum cholesterol levels.
Laufs
U
U
Klinik III für Innere Medizin, Universität zu Köln, Germany.
Gertz
K
K
Huang
P
P
Nickenig
G
G
Böhm
M
M
Dirnagl
U
U
Endres
M
M
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000201:enzymology; D000069059:Atorvastatin; D001777:Blood Coagulation / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects*; D002545:Brain Ischemia / Q000517:prevention & control*; D002784:Cholesterol / Q000097:blood; D004305:Dose-Response Relationship, Drug; D006538:Heptanoic Acids / Q000494:pharmacology*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D020244:Infarction, Middle Cerebral Artery / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D019001:Nitric Oxide Synthase / Q000187:drug effects* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D015539:Platelet Activation / Q000187:drug effects*; D010978:Platelet Factor 4 / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D015427:Reperfusion Injury / Q000517:prevention & control; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects; D001620:beta-Thromboglobulin / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors
D006538:Heptanoic Acids; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011758:Pyrroles; D012333:RNA, Messenger; D001620:beta-Thromboglobulin; D010978:Platelet Factor 4; D002784:Cholesterol; D000069059:Atorvastatin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; D020741:rho GTP-Binding Proteins