Dr. Alvarado-Livacic, Cristobal

Objective This study investigated the role of oxidative damage and nitric oxide (NO) synthases in the fetal heart using a model of intrauterine growth restriction induced by uteroplacental circulation restriction (UCR). Methods New Zealand white rabbits kept under 12-h light cycles, with food and water provided ad libitum, were subjected at day 25 of pregnancy to 40–50% uteroplacental artery ligation. We analyzed the gene expression of enzymes linked to nitric oxide synthesis (iNOS, eNOS, HO-1, and ARG-2), hypoxia inducible factor 1 alpha (HIF-1α), and the state of oxidative stress (protein carbonyl levels) in fetal heart homogenates. Additionally, we studied the histological morphology of the fetal heart. Results We found that fetal growth restriction was associated with a significant reduction in heart weight but a normal heart/body weight ratio in UCR animals. Hematoxylin and eosin staining showed normal left and right ventricular thickness but increased vessel dilatation with hyperemia in the hearts of the UCR group. We observed HIF-1α, eNOS, p-eNOS, and iNOS induction concomitant with intensified protein carbonyl levels but observed no changes in HO-1 or ARG-2 expression, suggesting increased NO and oxidative stress in the hearts of UCR animals. Conclusion Uteroplacental circulation restriction increased NO-linked enzymes, oxidative damage, and dilated coronary vessels in fetal hearts.

On renal ischemia-reperfusion (I/R) injury, recruitment of neutrophils during the inflammatory process promotes local generation of oxygen and nitrogen reactive species, which, in turn, are likely to exacerbate tissue damage. The mechanism by which inducible nitric oxide synthase (iNOS) is involved in I/R has not been elucidated. In this work, the selective iNOS inhibitor l- N6-(1-iminoethyl)lysine (l-NIL) and the NOS substrate l-arginine were employed to understand the role of NOS activity on the expression of particular target genes and the oxidative stress elicited after a 30-min of bilateral renal ischemia, followed by 48-h reperfusion in Balb/c mice. The main findings of the present study were that pharmacological inhibition of iNOS with l-NIL during an I/R challenge of mice kidney decreased renal injury, prevented tissue loss of integrity, and improved renal function. Several novel findings regarding the molecular mechanism by which iNOS inhibition led to these protective effects are as follows: 1) a prevention of the I/R-related increase in expression of Toll-like receptor 4 (TLR-4), and its downstream target, IL-1β; 2) reduced oxidative stress following the I/R challenge; noteworthy, this study shows the first evidence of glutathione S-transferase (GST) inactivation following kidney I/R, a phenomenon fully prevented by iNOS inhibition; 3) increased expression of clusterin, a survival autophagy component; and 4) increased expression of nuclear factor of activated T cells 5 (NFAT-5) and its target gene aquaporin-1. In conclusion, prevention of renal damage following I/R by the pharmacological inhibition of iNOS with l-NIL was associated with the inactivation of proinflammatory pathway triggered by TLR-4, oxidative stress, renoprotection (autophagy inactivation), and NFAT-5 signaling pathway.