Effects of NO synthase inhibitors, arginine-deficient diet, and amiloride in pregnant rats

Abstract

This study tests the hypothesis that nitric oxide synthase (NOS) inhibition is linked to NG-nitro-L-arginine methyl ester (L-NAME)-mediated intrauterine growth retardation (IUGR) and fetal limb reduction deficits (LRD) in pregnant dams. Administration of L-NAME (1 mg/ml) or aminoguanidine (AG, 500 micrograms/ml) in the drinking water or intraperitoneal administration of L-N5-(1-iminoethyl)-ornithine (L-NIO, 10 mg.kg-1.day-1) on gestational days 13-20 decreased nitrite and nitrate plus nitrate (RNI) levels in the urine and plasma and decreased RNI in incubates of aorta and fetal limbs compared with pregnant rats given amiloride (50 micrograms/ml) or water (control). Although all drugs caused fetal IUGR, only L-NAME and amiloride caused fetal deaths and LRD. Urine and tissue levels of RNI were unchanged in rats fed and arginine-free diet (AFD) on gestational days 13-20, and yet fetal IUGR, deaths, and LRD were prevalent. L-NAME potentiated the fetal abnormalities and resorptions. Plasma arginine concentrations decreased with AFD > > L-NAME > L-NIO. Plasma ornithine, a precursor for polyamine synthesis, decreased with AFD and increased with L-NAME. Thus inhibition of NOS is not linked to LRD. The ability of L-NAME and amiloride to produce fetal IUGR and LRD may result from L-NAME-mediated modulation of amino acid delivery to the fetus and amiloride-mediated inhibition of protein synthesis. Finally, IUGR appears unrelated to LRD.

Effect of Nω-Nitro-l-Arginine Methyl Ester–Induced Intrauterine Growth Restriction on Postnatal Lung Growth in Rats

“…Consequences on lung development were already described in a previous study on rat pups that were exposed to L-NAME in utero; the authors observed that the fetal lung/body weight ratio was significantly lower, suggesting delayed lung growth, compared with control pups (26). Several hypotheses can be suggested to explain the consequences of our L-NAMEinduced IUGR on lung development at birth in rat pups.…”

Within-litter variation in birth weight: impact of nutritional status in the sow

“…Amino acids in the arginine family (arginine, glutamine, glutamate, proline, aspartate, asparagine, citrulline, and ornithine) have been studied extensively given their prominent effects in improving litter size (Greenberg et al, 1997;Hazeleger et al, 2007;Mateo et al, 2007;Gao et al, 2012;Li et al, 2014). At the same time, dietary supplementation with 25.5 g/d L-arginine from Day 77 of pregnancy until term reduced within-litter variation in birth weight of live-born piglets by 20.6% and 25.4% in arginine and control groups, respectively (Quesnel et al, 2014).…”

The Nitric Oxide Synthesis Inhibitor Nω-Nitro-L-Arginine Methyl Ester (L-NAME) Causes Limb Defects in Mouse Fetuses: Protective Effect of Acute Hyperoxia

“…The L-arginine analog L-NAME, a nonselective inhibitor of NOS, has been shown to be teratogenic when administered to rats (3)(4)(5)(6)(7)(8). Limb reduction defects with associated characteristic areas of macroscopic hemorrhage were the most common phenotypic alterations noted (3)(4)(5)(6)(7)(8).…”

“…Limb reduction defects with associated characteristic areas of macroscopic hemorrhage were the most common phenotypic alterations noted (3)(4)(5)(6)(7)(8). L-NAME is not the only L-arginine analog known to cause dysmelia, as N -nitro-Larginine also induced limb defects (9).…”

“…Notably, disruptions similar to those induced by L-arginine analogs have been noted in knockout mice lacking eNOS (10,11). The current state of knowledge on L-NAME teratogenicity also includes the following facts: 1) the period of fetal vulnerability has an onset relatively late in gestation (3)(4)(5); 2) both oral (3)(4)(5)(6) and parenteral (5) treatments are effective; 3) limb dysmorphology is associated with reduced fetal viability (5); 4) both the teratogenic and fetus lethal effects are dose dependent (5); 5) defects are preceded by hemorrhages that appear in the limbs within hours of treatment (7,8); 6) fetal growth restriction and decrement in placental weight have been observed by some authors (3,4,6), but not by others (5); 7) the compound is teratogenic when instilled in the amnion, suggesting that it exerts its activity within the vasculature of the limb or placenta (7); 8) limb defects were prevented by concurrent administration of L-arginine or the NO donors sodium nitroprusside and S-nitroso-acetyl-penicillamine (4), suggesting that L-NAME initiates teratology via inhibition of NO synthesis; and 9) limb defects were reduced by coadministration of ␣-phenyl-N-tbutylnitrone, a radical spin trap antioxidant, and allopurinol, a xanthine oxidase inhibitor (7,8), suggesting a mechanistic role for radical oxygen species.…”