Expression of Lectin like Oxidized Low Density Lipoprotein Receptor-1 in the Spontaneous Hypertensive Rat with High Cholesterol Diet

BACKGROUND: Lectin-like, oxidized, low-density lipoprotein receptorreceptors (LOX-1) recognizes recognize vascular oxidized low-density lipoprotein (LDL), which may play an important role in the pathogenesis of atherosclerosis. We investigated the expressions expression of LOX-1 and redox-regulating thyoredoxinthioredoxin systems in a hypertension and hypercholesterolemia rat model. METHODS: Spontaneously hypertensive rats (SHR) and Wistar-Kyoto rat (WKY) rats were fed with a normal cholesterol diet (NC) and a high cholesterol diet (HC) for 4 weeks. Plasma LDL cholesterol levels and blood pressure were measured at 1 and 4 weeks. Histological changes of atherosclerosis in the vessel was evaluated by hematoxylin and eosin staining and immunocytochemistry. The expressions expression of LOX-1 and thyoredoixnthioredoxin were measured by Western western blot analysis. RESULTS: In the SHR groupsgroup, blood pressure after 4 weeks was significantly higher than initial levels. LDL-cholesterol levels in the SHR-HC group were increased at 4 weeks (15.3 +/- 2.6 mg/dL vs. 20.2 +/- 2.6 mg/dL, p < 0.01) compared with the SHR-NC group. In oxyblot analysis, the degree of oxidative stress of in the SHR-HC group was significantly higher than in the SHR-NC group (p < 0.05). The expressions expression of LOX-1 and Trx were was significantly increased in the SHR-HC group compared with the SHR-NC group (p < 0.05) on western blot analysis. Focal overexpressions overexpression of LOX-1 were was observed at the intima layer of the thoracic aorta, and was which wereonly observed in the SHR-HC group. CONCLUSIONS: The expressions expression of LOX-1 and oxidative stress were was significantly increased in the "hypertension with hypercholesterol" rat model. These findings suggested suggest that LOX-1 and redox systems may play a certain role in development and progression of atherosclerosis.

Expression Pattern of the Thioredoxin System in Human Endothelial Progenitor Cells and Endothelial Cells Under Hypoxic Injury

BACKGROUND AND OBJECTIVES: The thioredoxin (TRx) system is a ubiquitous thiol oxidoreductase pathway that regulates cellular reduction/oxidation status. Although endothelial cell (EC) hypoxic damage is one of the important pathophysiologic mechanisms of ischemic heart disease, its relationship to the temporal expression pattern of the TRx system has not yet been elucidated well. The work presented here was performed to define the expression pattern of the TRx system and its correlation with cellular apoptosis in EC lines in hypoxic stress. These results should provide basic clues for applying aspects of the TRx system as a therapeutic molecule in cardiovascular diseases. SUBJECTS AND METHODS: Hypoxia was induced with 1% O2, generated in a BBL GasPak Pouch (Becton Dickinson, Franklin Lakes, NJ, USA) in human endothelial progenitor cells (hEPC) and human umbilical vein endothelial cells (HUVEC). Apoptosis of these cells was confirmed by Annexin-V: Phycoerythrin flow cytometry. Expression patterns of TRx; TRx reductase; TRx interacting protein; and survival signals, such as Bcl-2 and Bax, in ECs under hypoxia were checked. RESULTS: Apoptosis was evident after hypoxia in the two cell types. Higher TRx expression was observed at 12 hours after hypoxia in hEPCs and 12, 36, 72 hours of hypoxia in HUVECs. The expression patterns of the TRx system components showed correlation with EC apoptosis and cell survival markers. CONCLUSION: Hypoxia induced significant apoptosis and its related active changes of the TRx system were evident in human EC lines. If the cellular impact of TRx expression pattern in various cardiovascular tissues under hypoxia or oxidative stress was studied meticulously, the TRx system could be applied as a new therapeutic target in cardiovascular diseases, such as ischemic heart disease or atherosclerosis.

Perivascular Delivery of Rapamycin in Pluronic Gel Inhibits Neointimal Hyperplasia in a Rat Carotid Artery Injury Model, and the Complementary Role of Carotid Arteriography

BACKGROUND AND OBJECTIVES: Rapamycin has been shown to inhibit the vascular smooth muscle cell migration and proliferation that contributes to neointimal formation. We investigated whether the perivascular delivery of rapamycin in Pluronic gel could inhibit neointimal hyperplasia in a rat carotid artery model, and we tested the usefulness of carotid arteriography. MATERIALS AND METHODS: To assess the kinetics of rapamycin's release from Pluronic gel, a [3H] thymidine incorporation assay was performed with using the media exposed to rapamycin in Pluronic gel for 10, 20, 60 and 120 min. We applied 100 microgram of rapamycin in Pluronic gel to the perivascular space of the carotid artery after the balloon injury (n=9), whereas only gel was applied in a control group (n=9). We performed the carotid arteriography and the morphometric analysis 14 days after injury. RESULTS: The [3H] thymidine incorporation assay showed a reduction of uptake in a time-dependent manner (86%, 48%, 45% and 40% of the control, respectively, at 10, 20, 60 and 120 minutes). The inhibiting effect of rapamycin on neointimal hyperplasia was identified on the carotid arteriography (mean luminal diameter; 0.75+/-0.11 vs. 0.60+/-0.12 arbitrary units, respectively, p< 0.05) and on the morphometric analysis (neointima area: 0.09+/-0.03 vs. 0.17+/-0.06 mm(2), respectively, p< 0.05). CONCLUSION: This study demonstrated that perivascular delivery of rapamycin in Pluronic gel inhibits neointimal hyperplasia in a rat carotid injury model. This animal model combined with arteriography can be used for developing new drugs to treat restenosis. In addition, this technique might be useful for vascular surgery such as coronary artery bypass grafting, arteriovenous fistula formation and peripheral vascular bypass graft insertion.

A Slight Variation in the Age of Rats Commonly used as a Carotid Artery Injury Model Results in a Large Difference in Neointima Formation

BACKGROUND AND OBJECTIVES: The degree of neointima formation after infliction of a carotid artery balloon injury in rats varies greatly depending on the sex, age, species and operational method. Strong variation is common, even within only a single control. This study attempted to find if there was any significant difference in neointima formation following a carotid artery balloon injury in 6 to 12 week old rats; the age commonly used in these types of experiments. MATERIALS AND METHODS: A balloon injury was inflicted on the carotid arteries of male SpragueDawley rats at 6 (n=9, 250-270 g), 8 (n=8, 280-300 g) and 11 weeks (n=10, 320-340 g) of age. Two weeks postoperation, a histomorphometric analysis was carried out. The vascular smooth muscle cell proliferation was measured in situ via BrdU incorporation 2 days after injury infliction. RESULTS: The neointima areas of the 6 week (0.22+/-0.04 mm2) and 8 week old groups (0.17+/-0.08 mm2) were 3.1 and 2.4 times larger than that of the 11 week old group (0.07+/-0.03 mm2). The mitotic index was significantly reduced in 11 week old group (n=4, 9.22+/-1.51%) compared to those of the 6 (n=4, 25.03+/-3.92%) and 8 week old (n=4, 21.66+/-3.66%) groups. CONCLUSION: Special care should be taken when interpreting neointima formation, as even a slight variation in the age and weight in 6 to 12 week old (250-340 g) rats; the age commonly used in these types of experiments, results in an unexpectedly large difference.