Corresponding distributions of increased endothelin-B receptor expression and increased endothelin-1 expression in the aorta of apolipoprotein E-deficient mice with advanced atherosclerosis

• Published in: Pathology international 2000-12, Vol.50 (12), p.929-936
• Main Authors: Kobayashi, Tsutomu, Miyauchi, Takashi, Iwasa, Satoshi, Sakai, Satoshi, Fan, Jianglin, Nagata, Michio, Goto, Katsutoshi, Watanabe, Teruo
• Format: Article
• Language: English
• Subjects: Animals; Aorta, Thoracic - metabolism; Aorta, Thoracic - pathology; apolipoprotein E-deficient mice; Apolipoproteins E - deficiency; Apolipoproteins E - genetics; Arteriosclerosis - genetics; Arteriosclerosis - metabolism; Arteriosclerosis - physiopathology; atherosclerosis; Blood Pressure - genetics; endothelin; endothelin receptor subtype; Endothelin-1 - genetics; Endothelin-1 - metabolism; Female; Gene Expression Regulation; Immunohistochemistry; Lipids - blood; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - metabolism; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin - genetics; Receptors, Endothelin - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - genetics; RNA, Messenger - metabolism; Systole
• ISSN: 1320-5463; 1440-1827
• DOI: 10.1046/j.1440-1827.2000.01152.x

Endothelin (ET)‐1 causes proliferation of vascular smooth muscle cells (VSMC). Although it has been reported that stimulation of ETB receptors as well as ETA receptors promote proliferation of VSMC, the precise distribution of each receptor subtype in atherosclerotic vessels is unknown. Previous studies demonstrated that apolipoprotein E (apoE)‐deficient mice have hypercholesterolaemia and develop severe atherosclerosis. To investigate the pathophysiological roles of vascular ET system in atherosclerosis, we examined preproET‐1 messenger ribonucleic acid expression in the aorta of apoE‐deficient mice, and performed immunohistochemical staining for ET‐1 and each ET receptor subtype (ETA and ETB receptors) in the atherosclerotic lesions of these mice. The level of preproET‐1 mRNA in the aorta was significantly higher in the apoE‐deficient mice than in the control mice. Strong ET‐1 staining was observed in the macrophage‐foam cells, intimal and medial VSMC in the atherosclerotic lesions of the apoE‐deficient mice. In addition, in the atherosclerotic lesions, strong ETB receptor staining was observed in the macrophage‐foam cells, intimal and medial VSMC, which distribution corresponded closely to that of ET‐1. ETA receptor staining was observed in the medial VSMC of both groups, but not in the macrophage‐foam cells of the apoE‐deficient mice. ETA receptor staining in the medial VSMC was stronger in the apoE‐deficient mice than in the control mice. These results suggest that the vascular ET system, including ET‐1 and ET receptors, is activated in the atherosclerotic lesions of apoE‐deficient mice. Since the distribution of strong ETB receptor staining corresponded closely to that of ET‐1, it is suggested that the ET system, mediated by ETB receptors, has an important role in the pathophysiology of the atherosclerotic lesions of apoE‐deficient mice.