Combined endothelial nitric oxide synthase upregulation and caveolin-1 downregulation decrease leukocyte adhesion in pial venules of ovariectomized female rats.
OBJECTIVE
We recently found that chronic estrogen depletion enhances leukocyte adhesion in pial venules in the female rat, while estrogen repletion decreases it. Estrogen-associated repression of inflammation may be due to upregulation of the endothelial isoform of nitric oxide synthase (eNOS) and concomitant downregulation of the endogenous inhibitor of eNOS, caveolin-1 (CAV-1). In this study we examined the effects of estrogen-independent eNOS upregulation (via simvastatin) and/or CAV-1 downregulation (antisense) on pial venular leukocyte adhesion in ovariectomized (OVX) rats.


METHODS
Intact and OVX rats were prepared with closed cranial windows. Adherent rhodamine 6G-labeled leukocytes were viewed by intravital microscopy. To demonstrate the importance of pial venular eNOS in the resistance to leukocyte adhesion, intact female rats were treated with a nonselective (N(G)-nitro-L-arginine) or a neuronal NOS-selective (7-nitroindazole) inhibitor. In OVX females, leukocyte adhesion was compared in the following groups: (1) untreated; (2) treated with simvastatin; (3) treated with simvastatin plus CAV-1 antisense; (4) treated with simvastatin plus CAV-1 missense; (5) treated with CAV-1 antisense; and (6) treated with CAV-1 missense.


RESULTS
In intact females, pial venular leukocyte adhesion was increased when total NOS activity, but not neuronal NOS activity alone, was blocked. In OVX rats, basal leukocyte adhesion, measured as the percentage of venular area occupied by adherent leukocytes, was attenuated (by approximately equal 60%) only in the presence of combined simvastatin plus CAV-1 antisense treatment.


CONCLUSIONS
Present findings demonstrate that eNOS-derived NO plays an important role in limiting cerebral venular leukocyte adhesion in female rats. These data also suggest that simvastatin-induced upregulation of eNOS expression in OVX rats will not restore eNOS function, as measured by decreased leukocyte adhesion, unless CAV-1 levels are reduced as well.
Santizo
Roberto A
RA
Neuroanesthesia Research Laboratory, Department of Anesthesiology, University of Illinois at Chicago, 60607, USA. rasp@uic.edu
Xu
Hao-Liang
HL
Galea
Elena
E
Muyskens
Steve
S
Baughman
Verna L
VL
Pelligrino
Dale A
DA
D000818:Animals; D051242:Caveolin 1; D022461:Caveolins / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D007962:Leukocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D010052:Ovariectomy; D010841:Pia Mater / Q000098:blood supply / Q000378:metabolism*; D051381:Rats; D019821:Simvastatin / Q000494:pharmacology; D015854:Up-Regulation / Q000502:physiology; D014699:Venules / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D004791:Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D019821:Simvastatin; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496316:Nos3 protein, rat