Mitochondrial Apoptotic Pathways: A Mechanism for Low Androgen-induced Vascular Endothelial Injury in Male Rats

Y.-X. Li; B. Jiang; Y. Li; F. Xia; J. Yu; L-z. Yang; C. Shi; Y.-L. Lu

doi:10.1055/s-0031-1271745

Hormone and Metabolic Research, Table of Contents

Horm Metab Res 2011; 43(6): 374-379
DOI: 10.1055/s-0031-1271745

Original Basic

Mitochondrial Apoptotic Pathways: A Mechanism for Low Androgen-induced Vascular Endothelial Injury in Male Rats

Y.-X. Li¹ , B. Jiang¹ , Y. Li¹ , F. Xia¹ , J. Yu¹ , L-z. Yang¹ , C. Shi¹ , Y.-L. Lu¹

¹Institution and Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, P. R. China

Abstract

The aim of the study was to investigate the role of mitochondrial apoptotic pathways in vascular endothelial injury in male rats with low androgen. 8 week-old adult male Sprague-Dawley (SD) rats were randomly divided into 3 groups (n=6/each group): control group, castrated group (low androgen), and replacement group (given androgen after castration). After 10 weeks, endothelial structure was observed by general light microscope and transmission electron microscope (TEM) respectively. Isolated mitochondria and mitochondrial membrane potential (MMP) were detected by fluorescence to access mitochondrial function. Chromatin degradation was measured by terminal deoxynucleotidyl transferase-mediated deoxyuridine-biotin nick end labeling (TUNEL) staining method. The mRNA and protein of bcl-2, cytochrome C (Cyt C), caspase-9, and caspase-3 were analyzed for apoptosis. Cell shrinkage and condensed chromatin, less mitochondria and a fall in MMP levels were observed in the castrated group, along with more apoptotic endothelial cells. Bcl-2 level was reduced and the expression of caspase-9, caspase-3 and Cyt C were elevated in the castrated group (p<0.05). But there was no significant difference between the replacement group and the control group (p>0.05). It was concluded that low androgen caused vascular endothelial damage. It may be, at least in part, related with the activating mitochondrial apoptotic pathways.

Key words

low androgen - endothelial cell - mitochondria - apoptosis

Full Text

References

1 Harman SM. Testosterone in older men after the Institute of Medicine Report: where do we go from here?. Climacteric. 2005; 8 124-135
2 Wu FC, Tajar A, Pye SR, Silman AJ, Finn JD, O’Neill TW, Bartfai G, Casanueva F, Forti G, Giwercman A, Huhtaniemi IT, Kula K, Punab M, Boonen S, Vanderschueren D. Hypothalamic-pituitary-testicular axis disruptions in older men are differentially linked to age and modifiable risk factors: the European Male Aging study. J Clin Endocrinol Metab. 2008; 93 2737-2745
3 Raynor MC, Carson CC, Pearson MD, Nix JW. Androgen deficiency in the aging male: a guide to diagnosis and testosterone replacement therapy. Can J Urol. 2007; 14 63-68
4 Yeap BB, Hyde Z, Almeida OP, Norman PE, Chubb SAP, Jamrozik K, Flicker L, Hankey GJ. Lower testosterone levels predict incident stroke and transient ischemic attack in older men. J Clin Endocrinol Metab. 2009; 94 2353-2359
5 Akishita M, Hashimoto M, Ohike Y, Ogawa S, Iijima K, Eto M, Ouchi Y. Low testosterone level is an independent determinant of endothelial dysfunction in men. Hypertens Res. 2007; 30 1029-1034
6 Gimbrone Jr MA. Vascular endothelium: An integrator of pathophysiologic stimuli in atherosclerosis. Am J Cardiol. 1995; 75 67B-70B
7 Schächinger V, Britten MB, Zeiher AM. Prognostic impact of coronary vasodilator dysfunction on adverse long-term outcome of coronary heart disease. Circulation. 2000; 101 1899-1906
8 Hill JM, Zalos G, Halcox JPJ, Schenke WH, Waclawiw MA, Quyyumi AA, Finkel T. Circulating endothelial progenitor cells, vascular function and cardiovascular risk. N. Engl J Med. 2003; 348 593-600
9 Lu YL, Kuang L, Zhu H, Wu H, Wang X-F, Pang Y-P, Wang N-J, Yu D-L. Changes in aortic endothelium ultrastructure in male rats following castration, replacement with testosterone and administration of 5alpha-reductase inhibitor. Asian J Androl. 2007; 9 843-847
10 Desagher S, Martinou JC. Mitochondria as the central control point of apoptosis. Cell Biology. 2000; 10 369-377
11 Bialik S, Cryns VL, Drincic A, Miyata S, Wollowick AL, Srinivasan A, Kitsis RN. The mitochondrial apoptotic pathway is activated by serum and glucose deprivation in cardiac myocytes. Circ Res. 1999; 85 403-414
12 Oshitari T, Yamamoto S, Hata N, Roy S. Mitochondria- and caspase-dependent cell death pathway involved in neuronal degeneration in diabetic retinopathy. Br J Ophthalmol. 2008; 92 552-556
13 Reers M, Smith TW, Chen LB. J-aggregate formation of a carbocyanine as a quantitative fluorescent indicator of membrane potential. Biochemistry.. 1991; 30 4480-4486
14 Scragg JL, Dallas ML, Peers C. Molecular requirements for L-type Ca2+ channel blockade by testosterone. Cell Calcium. 2007; 42 11-15
15 Seyrek M, Yildiz O, Ulusoy HB, Yildirim V. Testosterone relaxes isolated human radial artery by potassium channel opening action. J Pharmacol Sci. 2007; 103 309-316
16 Kimura N, Mizokami A, Oonuma T, Sasano H, Nagura H. Immunocytochemical localization of androgen receptor with polyclonal antibody in paraffin-embedded human tissues. J Histochem Cytochem. 1993; 41 671-618
17 Yu J, Akishita M, Eto M, Ogawa S, Son B-K, Kato S, Ouchi Y, Okabe T. Androgen Receptor-Dependent Activation of Endothelial Nitric Oxide Synthase in Vascular Endothelial Cells: Role of Phosphatidylinositol 3-Kinase/Akt Pathway. Endocrinology. 2010; 151 1822-1828
18 Karsan A, Harlan JM. Modulation of endothelial cell apoptosis: mechanisms and pathophysiological roles. J Atheroscler Thromb. 1996; 3 75-80
19 Mohamad N, Gutiérrez A, Núñez M, Cocca C, Martín G, Cricco G, Medina V, Rivera E, Bergoc R. Mitochondrial apoptotic pathways. Biocell. 2005; 29 149-161
20 Mignotte B, Vayssiere J-L. Mitochondria and apoptosis. Eur J Biochem. 1998; 252 1-15
21 Wong WW, Puthalakath H. Bcl-2 family proteins: the sentinels of the mitochondrial apoptosis pathway. IUBMB Life. 2008; 60 390-397
22 Zhou H, Ma Y, Zhou Y, Liu Z, Wang K, Chen G. Effects of magnesium sulfate on neuron apoptosis and expression of caspase, bax and bcl-2 after cerebral ischemia-reperfusion injury. Chin Med J. 2003; 116 1532-1534
23 Krajewski S, Krajewska M, Ellerby LM, Welsh K, Xie Z, Deveraux QL, Salvesen GS, Bredesen DE, Rosenthal RE, Fiskum G, Reed JC. Release of caspase-9 from mitochondria during neuronal apoptosis and cerebral ischemia. Proc Natl Acad Sci USA. 1999; 96 5752-5757
24 Hou J, Chong ZZ, Shang YC, Maiese K. FOXO3a governs early and late apoptotic endothelial programs during elevated glucose through mitochondrial and caspase signaling. Mol Cell. 2010; 321 194-206

Correspondence

Y.-L. Lu

Institution and Department of

Endocrinology and Metabolism

Shanghai Ninth People's

Hospital

Shanghai Jiaotong University

School of Medicine

Shanghai 200011

P. R. China

Phone: +86/21/2327 1247

Fax: +86/21/6313 6856

Email: luy662003@yahoo.com.cn