PPAR agonists are negative regulators of oxidative and nitrosative stress in fetuses from diabetic rats.

CAPOBIANCO E; MARTÍNEZ N; KURTZ M; JAWERBAUM A

Santiago, Chile

Congreso; 6th World Congress on developmental origins of health and disease (DOHAD); 2009

Sociedad DoHad

The intra-uterine milieu of a diabetic mother leads to alterations in fetal development and growth, with a consequent diabetogenic tendency in the offspring´s adulthood. Oxidative and nitrosative stress have been involved in the etiology of feto-placental anomalies. The peroxisome proliferator activated receptors (PPARs) are ligand activated nuclear receptors that regulate several inflammatory and developmental processes. The objective of this work was to evaluate the in vitro and in vivo putative effects of PPAR agonists as regulators of oxidative and nitrosative stress in fetuses from control and diabetic rats. Methods: from day 0.5 of pregnancy, control and streptozotocin-induced diabetic rats were fed with a standard  diet or with a standard diet supplemented with 6% olive oil (OO) or 6% safflower oil (SO), respectively containing 75% oleic acid and 75% linoleic acid, natural ligands of PPARs. Fetuses were explanted on day 13.5 of gestation. Fetuses from rats fed with the standard diet were cultured for 3 hours in the presence or absence of leukotriene B4 (LTB4, 0.1mM), carbaprostacyclin (cPGI2, 1mM) or 15deoxydelta 12,14prostaglandin J2 (15dPGJ2, 2mM), endogenous ligands for PPARa, PPARb and PPARg, respectively. In all the experimental groups, fetal concentration of nitrates/nitrites, stable metabolites of nitric oxide, was quantified by the Griess reaction, whereas, lipid peroxidation was assessed by measuring tiobarbituric acid reactive substances (TBARS). Nitrates/nitrites were expressed as nmol/mg protein and TBARS as nmol/µg protein. Results: In fetuses from control rats, nitrates/nitrites levels (13±1) were not modified by the addition of LTB4 (16.2±1.7) or cPGI2 (13.6±1.5), although they were decreased by 15dPGJ2 addition (8.7±0.4, p<0.01). In fetuses from diabetic rats, the levels of nitrates/nitrites were increased (30.6±3.3, p<0.01) when compared to controls, and additions of LTB4 (33.5±2.4), cPGI2 (23.7±2.8) or 15dPGJ2 (26.4±3.3) had no effect. Dietary treatments with OO (13.6±0.6) or SO (13±2.9) did not modify the levels of nitrates/nitrites in control fetuses (12.9±1.5), but in the diabetic fetuses (29.8±1.3), they greatly reduced nitrates/nitrites levels (OO (24.4±2.6, p<0.05) and SO (11.5±1.5, p<0.001)). TBARS levels in control fetuses (12±2) were not modified by the addition of LTB4 (12±2), cPGI2 (13±3) or 15dPGJ2 (16±4). In diabetic fetuses the levels of TBARS were elevated (20±8, p<0.0001) when compared to controls, and were reduced by the addition of LTB4 (9.7±2, p<0.0001), cPGI2 (12.4±3, p<0.001) and 15dPGJ2 (7±1, p<0.0001). Dietary treatments with OO (11.2±1.3) and SO (9.3±1.3) did not modify the levels of TBARS in control fetuses (9±1). Differently, in diabetic fetuses, the elevated levels of TBARS (20±2, p<0.01) were reduced by the maternal treatments with OO (13±2, p<0.05) and SO (13.5±0.4, p<0.01). Conclusion: In vitro treatments with PPAR agonists reduced oxidative stress in fetuses from diabetic rats.  Maternal treatment with diets supplemented with olive and safflower oils led to a reduction in fetal oxidative and nitrosative stress, possibly acting through PPAR activation. The obtained results highlight the anti-inflammatory properties of PPARs during fetal development, and show that they were more marked in the fetuses from diabetic mothers.