Vasculoprotective effects of rosiglitazone through modulating renin-angiotensin system in vivo and vitro.
BACKGROUND
The peroxisome proliferator-activated receptor-γ (PPARγ) agonist rosiglitazone has been suggested to exert cardiovascular protection through the improvement of lipid metabolism, anti-inflammation, anti-proliferation etc. However, whether renin-angiotensin system (RAS) is involved in the vascular protective effects of PPARγ agonists is not fully understood. The present study aimed to investigate the effects of the renin-angiotensin system in vascular protection mediated by PPARγ agonists.


OBJECTIVE
To investigate the actions of the renin-angiotensin system in vascular protection mediated by activation of PPARγ in vivo and in vitro.


METHODS
Rats were fed a regular diet (n = 8), a cholesterol-rich diet plus methylthiouracil (80 mg/Kg/day, n = 10), a cholesterol-rich diet plus methylthiouracil and rosiglitazone (4 mg/kg/day, n = 10). The rosiglitazone treatment was started from one month after the start of cholesterol-rich diet plus methylthiouracil, and lasted five months. Cultured vascular smooth muscle cells (VSMCs) were pretreated with 1 μmol/L angiotensin II (ANG II) for 6 h and randomly divided into the control group; the ANG II group (1 μmol/L ANG II); the groups respectively treated with different concentration rosiglitazone (20, 30, 50) μmol/L for 12 h; the groups treated with 30 μmol/L rosiglitazone for (6, 12, 24) h. Morphology changes of the aortic tissues were observed by hematoxylin and eosin stain. The VSMC growth was detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Angiotensin II and expression of angiotensin receptors were determined by radioimmunoassay, reverse transcription polymerase chain reaction (RT-PCR), western blot, and immunohistochemistry.


RESULTS
After 6 months, lipid deposition, VSMC proliferation and migration toward intima were observed in aortic tissues in the rats on a cholesterol-rich diet plus methylthiouracil, while these pathological changes induced by the cholesterol-rich diet were significantly suppressed by rosiglitazone. In addition, VSMC proliferation induced by ANG II was markedly inhibited by rosiglitazone. Rosiglitazone markedly down-regulated expression of angiotensin type 1 receptor (AT1R) and up-regulated expression of angiotensin type 2 receptor (AT2R) in the aortic tissues and ANG II-treated VSMCs.


CONCLUSIONS
The present study demonstrated that PPARγ agonist rosiglitazone suppressed ANG II-induced VSMC proliferation in vitro and early atherosclerotic formation evoked by cholesterol-rich diet in vivo. These vasculoprotective effects of rosiglitazone were mediated at least partially by reduction in local tissue ANG II concentration, down-regulation of AT1R expression and up-regulation of AT2R expression both at the mRNA and protein levels.
Department of Cardiology, Zhongda Hospital of Southeast University, Nanjing, China. rlq6345@126.com
Liqun
L
Ren
Naifeng
N
Liu
Hong
H
Zhi
Yingjuan
Y
Li
Yanzhi
Y
Li
Rining
R
Tang
Zulong
Z
Sheng
D000804:Angiotensin II / Q000097:blood; D000818:Animals; D001018:Aortic Diseases / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D050197:Atherosclerosis / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D015153:Blotting, Western; D002317:Cardiovascular Agents / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006937:Hypercholesterolemia / Q000150:complications / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D007150:Immunohistochemistry; D008055:Lipids / Q000097:blood; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D047495:PPAR gamma / Q000819:agonists* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D044139:Receptor, Angiotensin, Type 2 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000187:drug effects*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology*; D013997:Time Factors
D002317:Cardiovascular Agents; D008055:Lipids; D047495:PPAR gamma; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D045162:Thiazolidinediones; D000077154:Rosiglitazone; D000804:Angiotensin II
Biochem Biophys Res Commun. 1996 Sep 24;226(3):862-8
8831702
Cardiovasc Res. 2004 Apr 1;62(1):135-44
15023560
Anal Biochem. 1976 May 7;72:248-54
942051
Endocrinol Metab Clin North Am. 2006 Sep;35(3):561-74, ix
16959586
Lab Invest. 2003 Dec;83(12):1715-21
14691289
Hypertension. 2006 Nov;48(5):824-5
17015780
Circulation. 2002 Dec 10;106(24):3126-32
12473562
Am J Cardiol. 2001 Oct 18;88(8A):10K-15K
11694213
Circulation. 1999 Nov 23;100(21):2131-4
10571970
Circulation. 2004 Dec 21;110(25):3849-57
15596561
Stroke. 2010 Jun;41(6):1266-70
20395611
Am J Med Sci. 2002 Jan;323(1):17-24
11814137
Mol Cell Biochem. 2003 Apr;246(1-2):25-30
12841339
Am J Physiol Heart Circ Physiol. 2007 Dec;293(6):H3726-31
17965276
J Biol Chem. 2000 Jun 16;275(24):18279-83
10764814
Circ Res. 1998 Nov 30;83(11):1097-103
9831704
N Engl J Med. 2006 Dec 7;355(23):2427-43
17145742
N Engl J Med. 2007 Jul 5;357(1):28-38
17551159
Circulation. 2004 Nov 9;110(19):3062-7
15277329
Cardiovasc Diabetol. 2010 May 19;9:19
20482873
Korean Diabetes J. 2010 Jun;34(3):191-9
20617080
Cardiovasc Diabetol. 2010 Oct 18;9:64
20955583
Arterioscler Thromb Vasc Biol. 2001 Mar;21(3):365-71
11231915
JAMA. 2007 Sep 12;298(10):1189-95
17848653
Lancet. 2006 Sep 23;368(9541):1096-105
16997664
Circulation. 1997 Jan 21;95(2):473-8
9008466
Zhonghua Xin Xue Guan Bing Za Zhi. 2007 Nov;35(11):1050-6
18269830
Vascul Pharmacol. 2005 Feb;42(3):109-18
15792928
FEBS Lett. 1999 Jun 11;452(3):277-82
10386606
Circulation. 2000 Jan 25;101(3):235-8
10645917
Br J Pharmacol. 2001 Oct;134(4):865-70
11606327
Free Radic Biol Med. 2002 Oct 15;33(8):1026-36
12374614
Circulation. 2003 Dec 2;108(22):2805-11
14610009
N Engl J Med. 2007 Jun 14;356(24):2457-71
17517853
Circulation. 2000 Mar 21;101(11):1311-8
10725292
Circ Res. 2002 Apr 5;90(6):703-10
11934839
Arterioscler Thromb Vasc Biol. 2001 Dec;21(12):1891-5
11742860
Atherosclerosis. 2002 Aug;163(2):229-39
12052469
J Atheroscler Thromb. 2008 Apr;15(2):82-6
18385537
J Clin Invest. 1995 Feb;95(2):651-7
7860748
Circulation. 2001 Nov 20;104(21):2588-94
11714655
Curr Atheroscler Rep. 2000 Jul;2(4):327-35
11122762
Circulation. 2005 Sep 13;112(11):1636-43
16145000
Clin Sci (Lond). 2002 Aug;103 Suppl 48:16S-20S
12193046
Am J Physiol Heart Circ Physiol. 2006 Jan;290(1):H390-7
16155101
Endocrinology. 2001 Jul;142(7):3125-34
11416035
J Am Soc Nephrol. 2007 Aug;18(8):2311-9
17634441
Hypertension. 1999 Jan;33(1 Pt 2):335-9
9931126
Am J Cardiovasc Drugs. 2006;6(4):231-42
16913824
Am J Hypertens. 2005 Apr;18(4 Pt 1):493-9
15831358