Abstract 5519: Enhanced Age-related Endothelial Dysfunction in Genetic Deletion of JunD
JunD is a transcription factor that regulates genes involved in antioxidant defense. This study aimed to investigate whether JunD deficient mice (JunD−/−) are more prone to age-related, oxidative stress-mediated, endothelial dysfunction in comparison to age-matched wild type (WT) mice.
Methods. Thoracic aortic rings from young (3 months old), middle aged (6 months old) and old (22 months old) male JunD−/− and WT mice were suspended for isometric tension recording. Endothelium-dependent relaxation to acetylcholine (Ach, 10−9–10−6mol/L) was assessed after submaximal contraction with norepinephrine (10−6mol/L). Calcium ionophore stimulated nitric oxide (NO), superoxide anion (O2−) and peroxynitrite (ONOO−) were measured with electrochemical nanosensors placed near the surface (5±2 μm) of a single endothelial cell.
Results. The age-associated impairment of endothelium-dependent relaxations to Ach (Ach, 10−9–10−6 mol/L) was significantly enhanced in JunD−/− as compared to age-matched WT. Maximal relaxations were 55±5 vs 78±4% at 6 months and 39±3 vs 50±2% at 22 months for JunD−/− and WT mice, respectively (n=6 – 8, p<0.05 vs age-matched group). Endothelium-independent relaxations to sodium nitroprusside (10−10–10−5 mol/L) did not differ in JunD−/− and WT of different age groups (n=6 – 8, p<NS). Age-induced decrease of NO production was higher in JunD−/− as compared with WT (475±32 vs 350±28 nmol/L and 358±26 vs 220±23 nmol/L for 6 and 22 months old WT and JunD−/−, respectively; n=3–5, p<0.05 vs age-matched group). O2− and ONOO− generation increased with age in WT and more significantly in JunD−/−mice (O2−, 67±6 vs 103±8 nmol/L and 116±9 vs 210±16 nmol/L; ONOO−, 224±17 vs 319±22 nmol/L and 313±21 vs 492±29 nmol/L for 6 and 22 months old WT and JunD−/−, respectively; n= 3–5, p<0.05 vs age-matched group). eNOS and MnSOD protein expression was downregulated in JunD−/− mice as compared with WT controls (n=3–5, p<0.05 vs age-matched group). Relaxations to Ach in JunD−/− mice were restored by free radical scavengers superoxide dismutase (SOD) (150 U/ml) and catalase (1200 U/ml).
Conclusion. Our results indicate that JunD protects against vascular oxidative stress providing new insights into the pathophysiology of age-associated endothelial dysfunction.