PPARgamma in endothelial cells influences high fat diet-induced hypertension.
BACKGROUND
Peroxisome proliferator-activated receptor gamma (PPARgamma) ligands improve human hypertension. However, the mechanism and site of this effect remains unknown, confounded by PPARgamma expression in many cell types, including endothelial cells (ECs).


METHODS
To evaluate the vascular role of PPARgamma we used a conditional null mouse model. Specific disruption of PPARgamma in ECs was created by crossing Tie2-Cre+ transgenic (T2T+) and PPARgamma-floxed (fl/fl) mice to generate PPARgamma (fl/fl)T2T+ (PPARgamma E-null) mice. Conscious 8- to 12-week-old congenic PPARgamma (fl/fl)Cre- (wild type) and PPARgamma E-null mice were examined for changes in systolic blood pressure (BP) and heart rate (HR), untreated, after 2 months of salt-loading (drinking water), and after treatment for 3 months with high fat (HF) diet alone or supplemented during the last 2 weeks with rosiglitazone (3 mg/kg/d).


RESULTS
Untreated PPARgamma E-nulls were phenotypically indistinguishable from wild-type littermates. However, compared to similarly treated wild types, HF-treated PPARgamma E-nulls had significantly elevated systolic BP not seen after normal diet or salt-loading. Despite sex-dependent baseline differences, salt-loaded and HF-treated PPARgamma E-nulls of either sex had significantly elevated HR versus wild types. Interestingly, rosiglitazone improved serum insulin levels, but not HF diet-induced hypertension, in PPARgamma E-null mice.


CONCLUSIONS
These results suggest that PPARgamma in ECs not only is an important regulator of hypertension and HR under stressed conditions mimicking those arising in type 2 diabetics, but also mediates the antihypertensive effects of rosiglitazone. These data add evidence supporting a beneficial role for PPARgamma-specific ligands in the treatment of hypertension, and suggest therapeutic strategies targeting ECs may prove useful.
Nicol
Christopher J
CJ
Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Adachi
Masahiro
M
Akiyama
Taro E
TE
Gonzalez
Frank J
FJ
D000284:Administration, Oral; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology; D004041:Dietary Fats / Q000008:administration & dosage* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000378:metabolism*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000209:etiology*; D008024:Ligands; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D047495:PPAR gamma / Q000378:metabolism*; D000077154:Rosiglitazone; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D045162:Thiazolidinediones / Q000494:pharmacology
D000959:Antihypertensive Agents; D004041:Dietary Fats; D008024:Ligands; D047495:PPAR gamma; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D012965:Sodium Chloride