Lack of protective action of cysteine against the fetotoxic effect of monocrotaline

Prenatal Amino Acid Supplementation to Improve Fetal Growth: A Systematic Review and Meta-Analysis

Aberrant fetal growth remains a leading cause of perinatal morbidity and mortality and is associated with a risk of developing non-communicable diseases later in life. We performed a systematic review and meta-analysis combining human and animal studies to assess whether prenatal amino acid (AA) supplementation could be a promising approach to promote healthy fetal growth. PubMed, Embase, and Cochrane libraries were searched to identify studies orally supplementing the following AA groups during gestation: (1) arginine family, (2) branched chain (BCAA), and (3) methyl donors. The primary outcome was fetal/birth weight. Twenty-two human and 89 animal studies were included in the systematic review. The arginine family and, especially, arginine itself were studied the most. Our meta-analysis showed beneficial effects of arginine and (N-Carbamyl) glutamate (NCG) but not aspartic acid and citrulline on fetal/birth weight. However, no effects were reported when an isonitrogenous control diet was included. BCAA and methyl donor supplementation did not affect fetal/birth weight. Arginine family supplementation, in particular arginine and NCG, improves fetal growth in complicated pregnancies. BCAA and methyl donor supplementation do not seem to be as promising in targeting fetal growth. Well-controlled research in complicated pregnancies is needed before ruling out AA supplements or preferring arginine above other AAs.

Sex difference in monocrotaline-induced developmental toxicity and fetal hepatotoxicity in rats

Pyrrolizidine alkaloids (PAs) are a class of hepatic toxins widely existing in plants. Cytochromes P450 (CYP) mediates PA bioactivation and toxicities in mammals. It has been reported that PAs can induce developmental toxicity, but systematic research is lacking. In this study, we investigated developmental toxicity of monocrotaline (MCT) in rats. Pregnant rats were administered with MCT (20 mg/kg) intragastrically from gestation day 9 to 20, followed by determination of changes in fetal growth, hepatic morphology, serum biochemical indices, and indicators of hepatocytes apoptosis. MCT was found to induce developmental toxicity and fetal hepatotoxicity, particularly in female fetuses. Metabolic activation was also studied by examination of bioactivation efficiency of MCT in fetal liver microsomes, serum MCT, pyrrole-protein adduction derived from MCT, and hepatic CYP3 A expression of fetuses in vivo. Male fetuses showed greater basal MCT bioactivation than that of female fetuses, but continuous exposure to MCT caused a selective CYP3 A induction in female fetuses, which may contribute to the sex difference in MCT-induced developmental toxicity.

Oxidative hepatotoxicity effects of monocrotaline and its amelioration by lipoic acid, S-adenosyl methionine and vitamin E

Liver is the major site for several xenobiotics metabolism, and formation of toxic metabolites that may be hepatotoxic, therefore the burden of metabolism and exposure to dangerous chemicals make liver vulnerable to a variety of disorders. Our work aimed to investigate the effects of some antioxidants such as lipoic acid (LA), S-adenosyl methionine (SAM) and vitamin E in a trail to investigate the possibility of using these substances to relieve and protect liver from exposure to monocrotaline (MCT). Twenty-five mature adult rats were classified into five groups (five rats in each group), control group, MCT-induced hepatic damage, LA+MCT, SAM+MCT and vitamin E+MCT group. Homogenates of liver samples were used for measuring the oxidative biomarkers and hepatic antioxidant status. The results showed that administration of vitamin E, SAM and LA caused a significant increase in liver glutathione contents, glutathione reductase, glutathione peroxidase and glutathione-S-transferase activities and a significant decrease in hepatic catalase and superoxide dismutase. We could conclude that administration of natural LA, SAM and vitamin E before and after MCT injection modulate the hepatic oxidative stresses induced by MCT in various extents.

Synergistic effects of pyrrolizidine alkaloids and lipopolysaccharide on preterm delivery and intrauterine fetal death in mice

Preterm birth is the leading cause of death for newborn infants, and lipopolysaccharide (LPS) is commonly used to induce preterm delivery in experimental animals. Pyrrolizidine alkaloids (PAs) are widespread and occur in foods, herbs, and other plants. This study was to investigate the synergistic effects of LPS and two representative PAs, retrorsine (RTS) and monocrotaline (MCT), on preterm delivery and fetal death. Pregnant Kunming mice were divided into seven groups: control, RTS, MCT, LPS, RTS+LPS and two MCT+LPS groups. Animals in PAs and PAs+LPS groups were dosed intragastrically with RTS (10mg/kg) or MCT (20 mg/kg or 60 mg/kg) from gestational day (GD) 9 to GD16; mice given LPS were injected intraperitoneally with 150 μg/kg on GD15.5. Latencies to delivery, numbers of pups live and dead at birth were recorded, and livers of live neonates were collected. The incidence of LPS-induced preterm birth was enhanced in dams pretreated with MCT, and combination of PAs and LPS increased fetal mortality from PAs. The enhancement of LPS-induced preterm delivery and fetal demise in animals exposed chronically to PAs and other substances found in foods and beverages consumed widely by humans merits further focused investigation.