Endogenous superoxide dismutase activation by oral administration of riboflavin reduces abdominal aortic aneurysm formation in rats.

OBJECTIVE: Vitamin B2 (riboflavin) reportedly has an antioxidant effect through superoxide dismutase (SOD) activation. However, the effect of riboflavin on abdominal aortic aneurysm (AAA) has never been investigated. In the present study, we examined the hypothesis that riboflavin has a protective effect on AAA formation in an experimental rat model. METHODS: The AAA model, which was induced with intraluminal elastase and extraluminal calcium chloride, was created in 36 rats. The 36 rats were divided into a riboflavin group (group R; 25 mg/kg/d), and control group (carboxymethyl cellulose). Riboflavin administration by gastric gavage once per day was started at 3 days before aneurysm preparation. On day 3, SOD activity in aneurysm walls was assayed. On day 7, reactive oxygen species (ROS) levels were semiquantified by dihydroethidium staining, and the oxidation product of DNA produced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), was measured by immunohistochemical staining. Histopathologic examination (hematoxylin/eosin and elastica Van Gieson staining) was performed on day 28, and the AAA dilatation ratio was calculated to evaluate the protective effect of riboflavin. RESULTS: On day 3, SOD activity was significantly increased in aneurysm walls by riboflavin administration (370 ± 204 U/mL in normal, 334 ± 86 U/mL in control, 546 ± 143 U/mL in group R; P = .021). On day 7, ROS levels and 8-OHdG-positive cells in aneurysm walls were significantly decreased by riboflavin treatment (ROS levels: 1.0 ± 0.1 in normal, 4.5 ± 0.4 in control, 3.1 ± 0.5 in group R, P < .01; 8-OHdG-positive cells: 30 ± 2 cells in normal, 148 ± 20 cells in control, 109 ± 15 cells in group R, P < .01). Riboflavin treatment significantly reduced matrix metalloproteinase (MMP)-9 messenger RNA expression in aneurysm walls (relative expression: MMP-9: 0.4 ± 0.7 in normal, 2.6 ± 1.3 in control, 0.5 ± 0.3 in group R, P < .01). On day 28, the aortic walls were less dilated and had higher elastin content in group R than in control (dilatation ratio: 194.9% ± 10.9% in control, 158.6% ± 2.5% in group R; P <.01). CONCLUSIONS: Riboflavin treatment prevents AAA formation in a rat model through an antioxidant effect and might be a potent pharmacologic agent for AAA treatment in clinical practice.

Glucagon-like peptide-1 prevented abdominal aortic aneurysm development in rats.

PURPOSE: To demonstrate the protective effect of glucagon-like peptide 1 (GLP-1) signaling on the cardiovascular system, we conducted this study to show that the GLP-1 receptor analog (lixisenatide) could inhibit abdominal aortic aneurysm (AAA) development in rats. METHODS: Lixisenatide was injected subcutaneously 7 days after aneurysm preparation. We evaluated reactive oxygen species (ROS) expression by dihydroethidium staining and 8-hydroxydeoxyguanosine (8-OHdG; the oxidation product of DNA) by immunohistochemical staining. We also analyzed the effect of GLP-1 signaling on the inflammatory response. Histopathological examination was done on day 28, and the AAA dilatation ratio was calculated. RESULTS: On day 14, ROS expression and 8-OHdG-positive cells in the aneurysm walls were seen to have been significantly decreased by lixisenatide treatment. Western blot analysis showed decreased ERK expression. There was significantly reduced tumor necrosis factor-α mRNA expression in the aneurysm walls and CD68-positive cell infiltration in the aneurysm walls. On day 28, it was evident that the lixisenatide had dramatically reduced aneurysm development in the rats. CONCLUSION: GLP-1 elevation inhibits AAA development in rats through its anti-oxidant and anti-inflammatory effects. Thus, GLP-1 could be a potent pharmacological target for AAA treatment.

Controlled release of ascorbic acid from gelatin hydrogel attenuates abdominal aortic aneurysm formation in rat experimental abdominal aortic aneurysm model.

OBJECTIVE: Abdominal aortic aneurysms (AAAs) are associated with oxidative stress and inflammatory response. We investigated the hypothesis that the known antioxidant ascorbic acid, which can also promote elastin and collagen production by smooth muscle cells, would prevent AAA formation in a rat model. METHODS: An intraluminal elastase and extraluminal calcium chloride-induced rat AAA model was used, and the animals were divided into three groups: control (group C, n = 18), the aorta wrapped with a saline-impregnated gelatin hydrogel sheet (group G, n = 18), and the aorta wrapped with a gelatin hydrogel sheet incorporating ascorbic acid (group A, n = 18). Wrapping of the sheet was completed at the end of treatment for AAA creation. The aortic dilatation ratio was measured, and aortic tissues were further examined for oxidative stress and oxidative DNA damage using biochemical and histologic techniques. RESULTS: Aortic dilatation at both 4 and 8 weeks was inhibited in group A (dilatation ratio [%] at 4 weeks: 186.2 ± 21.8 in group C, 152.3 ± 10.2 in group G, 126.8 ± 11.6 in group A; P < .0001; dilatation ratio [%] at 8 weeks: 219.3 ± 37.5 in group C, 194.0 ± 11.6 in group G, 145.7 ± 8.3 in group A; P = .0002). Elastin and collagen content were significantly preserved in group A (elastin, P = .0015; collagen, P < .0001). The messenger RNA expressions of matrix metalloproteinase (MMP)-9, monocyte chemotactic protein-1, interleukin-1ß, and tissue necrosis factor-α (P = .0024, P < .0001, P < .0001, and P < .0001, respectively) were downregulated in group A (P = .0024), whereas tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 were both upregulated in group A (TIMP-1, P = .0014; TIMP-2, P < .0001). Gelatin zymography showed activities of pro-MMP-2, MMP-2, and MMP-9 were significantly suppressed in group C (P < .0001 for each). Reactive oxygen species expression and 8-hydroxydeoxyguanosine and cluster of differentiation 68 staining were significantly suppressed in group A (reactive oxygen species expression, P < .0001; 8-hydroxydeoxyguanosine-positive cells, P < .0001; cluster of differentiation 68 positive cells, P < .0001). CONCLUSIONS: Controlled release of ascorbic acid using gelatin hydrogel sheet-attenuated AAA formation through antioxidant and anti-inflammatory effect, regulation of MMP-2, TIMP-1, and TIMP-2, and preserving elastin and collagen in this animal model.

Orally administered dipeptidyl peptidase-4 inhibitor (alogliptin) prevents abdominal aortic aneurysm formation through an antioxidant effect in rats.

OBJECTIVE: Dipeptidyl peptidase-4 (DPP-4) inhibitor, a novel antidiabetic drug, has a cardioprotective effect on ischemia-reperfusion injury through an antioxidant effect. However, the effect of DPP-4 inhibitor on aneurysm formation has not been investigated. We aimed to test the hypothesis that the DPP-4 inhibitor, alogliptin, attenuates vascular oxidative stress and thus inhibits abdominal aortic aneurysm (AAA) formation. METHODS: AAAs were created with intraluminal elastase and extraluminal calcium chloride in 36 male rats. Rats were divided into three groups: a low dose of alogliptin group (group LD; 1 mg/kg/d), a high-dose group (group HD; 3 mg/kg/d), and a control group (group C, water). Alogliptin was administered by gastric gavage once daily beginning 3 days before surgery. On day 7 after aneurysm preparation, reactive oxygen species (ROS) expression was semiquantified by dihydroethidium staining, and the oxidation product of DNA produced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), was measured by immunohistochemical staining. Blood glucose concentrations were measured. Hematoxylin and eosin and elastica Van Gieson stainings were performed on day 28, and the AAA dilatation ratio was calculated. RESULTS: On day 7 (six in each group), dihydroethidium staining of the aneurysm wall showed a reduced level of ROS expression (4.6 ± 0.6 in group C, 2.7 ± 0.3 in group LD, and 1.7 ± 0.5 in group HD; P < .0001) and showed fewer 8-OHdG-positive cells in alogliptin-treated samples (138.1 ± 7.4 cells in group C, 102.5 ± 4.5 cells in group LD, and 66.1 ± 4.5 cells in group HD; P < .0001) The treatment significantly reduced messenger RNA expression of matrix metalloproteinases (MMPs) in aneurysm walls (relative expression: MMP-2: 2.1 ± 0.4 in group C, 1.3 ± 0.3 in group LD, and 0.9 ± 0.2 in group HD; P < .001; MMP-9: 2.0 ± 0.5 in group C, 0.3 ± 0.3 in group LD, and 0.3 ± 0.2 in group HD; P < .001). On day 28 (six in each group), the aortic wall in groups LD and HD was less dilated (dilatation ratio: 199.2% ± 11.8% in group C, 159.6% ± 2.8% in group LD, and 147.1% ± 1.9% in group HD; P < .02 group C vs HD) and had higher elastin content than in group C. The difference in blood glucose levels among the three groups was not significant. CONCLUSIONS: The DPP-4 inhibitor, alogliptin, attenuates aneurysm formation and expansion dose-dependently in a rat AAA model via an antioxidative action.