Oxidative stress and diabetes in pregnant rats

A considerable amount of clinical and experimental evidence now exists suggesting the involvement of free radical-mediated oxidative processes in the pathogenesis of diabetic complications. If the diabetic state is associated with a generalized increase in oxidative stress, it might well be reflected in the alterations in embryonic and fetal development during pregnancy. In the present study, incidence of the malformed fetuses, biochemical parameters and antioxidant system activity of streptozotocin (STZ)-induced diabetic pregnant rats was investigated and the results obtained were compared with those of the control group (non-diabetic). Virgin female Wistar rats were injected with 40 mg/kg streptozotocin (STZ) before mating. All the females were killed on Day 21 of pregnancy and the fetuses were analyzed. A maternal blood sample was collected by venous puncture and the maternal liver was removed for biochemical measurement. The diabetic dams presented hyperglycemia, hyperlipemia, hypertriglyceridemia, hypercholesterolemia, hyperuricemia, decreased reduced glutathione (GSH), hepatic glycogen and superoxide dismutase (SOD) determinations. There was an increased incidence of skeletal and visceral malformation in fetuses from diabetic rats. Our findings suggest that oxidative stress occurs in the diabetic pregnant state, which might promote maternal homeostasis alterations. These diabetic complications might be a contributory factor to conceptus damage causing embryonic death (abortion/miscarriage) or the appearance of malformations in the fetuses of diabetic dams. Antioxidant treatment of women with diabetes may be important in future attempts to prevent congenital malformations.     

Oxidative stress induced by gibberellic acid on kidney tissue of female rats and their progeny: biochemical and histopathological studies

Gibberellic acid (GA₃) is an endogenous plant growth regulator used worldwide in agriculture. The objective of this study was to investigate the effects of GA₃ on the kidney function of adult rats and their pups. Female Wistar rats were given daily 200 ppm GA₃ in drinking water from the 14th day of pregnancy until day 14 after delivery. GA₃ induced nephrotoxicity, as evidenced by a reduction in the 24-h urine volume and an increase in plasma creatinine, urea and uric acid levels. Nephrotoxicity was objectified by a significant increase of malondialdehyde level and a decrease of antioxidant enzyme activities like catalase, superoxide dismutase, glutathione peroxidase and glutathione content in kidneys of suckling pups and their mothers. Kidney histological studies confirmed biochemical parameters. We concluded that the exposure of rats to GA₃ induced oxidative stress and histopathological changes in kidneys of suckling rats and their mothers during late pregnancy and early postnatal periods.     

Oxidative damage in pregnant diabetic rats and their embryos

Free radical mechanisms may be involved in the teratogenesis of diabetes. The contribution of oxidative stress in diabetic complications was investigated from the standpoint of oxidative damage to DNA, lipids, and proteins in the livers and embryos of pregnant diabetic rats. Diabetes was induced prior to pregnancy by the administration of streptozotocin (45 mg/kg). Two groups of diabetic rats were studied, one without any supplementation (D) and another treated during pregnancy with vitamin E (150 mg/d by gavage) (D + E). A control group was also included (C). The percentage of malformations in D rats were 44%, higher than the values observed in C (7%) and D + E (12%) animals. D Group rats showed a higher concentration of thiobarbituric acid reactive substances in the mother's liver, however, treatment with vitamin E decreased this by 58%. The levels of protein carbonyls in the liver of C, D, and D + E groups were similar. The "total levels" of the DNA adducts measured, both in liver and embryos C groups were similar to the D groups. Treatment of D groups with vitamin E reduced the levels by 17% in the liver and by 25% in the embryos. In terms of the "total levels" of DNA adducts, the embryos in diabetic pregnancy appear to be under less oxidative stress when compared with the livers of their mothers. Graziewicz et al. (Free Radical Biology & Medicine, 28:75-83, 1999) suggested "that Fapyadenine is a toxic lesion that moderately arrests DNA synthesis depending on the neighboring nucleotide sequence and interactions with the active site of DNA polymerase." Thus the increased levels of Fapyadenine in the diabetic livers and embryos may similarly arrest DNA polymerase, and in the case of this occurring in the embryos, contribute to the congenital malformations. It is now critical to probe the molecular mechanisms of the oxidative stress-associated development of diabetic congenital malformations.     

Changes of glucocorticoid level in plasma and adrenal glands of pregnant rats and their offspring after antenatal stress of different etiology

We investigated the glucocorticoid level in plasma and adrenal glands of pregnant rats in the period of early organogenesis. Tests were performed 24 hours after stress of different etiology (acute hypobaric hypoxia, intermittent normobaric hypoxia, and immobilization) and then repeated in the adult offspring. There was a significant decrease in the glucocorticoid level in pregnant rats 24 hours after hypoxic stress. Various changes of the basal glucocorticoid level were found in the offspring after antenatal stress. Changes were mostly found in female offspring.     

Lack of adverse effects in pregnant/lactating female rats and their offspring following pre- and postnatal exposure to ELF magnetic fields

We have recently reported that exposure of pregnant rats to 60 Hz at field strengths up to 0.5 mT during the entire period of pregnancy did not induce any biologically significant effects on both pregnant dams and embryo-fetal development. The present study was carried out to investigate the potential effects of gestational and lactational MF exposure on pregnancy, delivery, and lactation of dams and growth, behavior, and mating performance of their offspring in rats. Timed-pregnant female Sprague-Dawley (SD) rats (24/group) received continuous exposure to 60 Hz magnetic field (MF) at field strengths of 0 (sham control), 5 microT, 83.3 microT, or 0.5 mT. Dams received MF or sham exposures for 21 h/day from gestational day 6 through lactational day 21. Experimentally generated MF was monitored continuously throughout the study. No exposure-related changes in clinical signs, body weight, food consumption, pregnancy length, and necropsy findings were observed in dams. Parameters of growth, behavior, and reproductive performance of offspring showed no changes related to MF exposure. There were no adverse effects on embryo-fetal development of F2 offspring from dams exposed to MF. In conclusion, exposure of pregnant SD rats to 60 Hz at field strengths up to 0.5 mT from gestational day 6 to lactational day 21 did not produce biologically significant effects in dams, F1 offspring, or F2 fetuses.     

Disaccharidase activities in pregnant and lactating rats

The changes in intestinal disaccharidase activities in pregnancy and lactation could be explained as a result of an adaptation to the energy demands of each reproductive stage. To examine these changes, disaccharidase activities (lactase, sucrase, maltase, and trehalase) were measured in the jejunum and ileum of virgin, pregnant and lactating Wistar rats. Minor changes in disaccharidase activities were observed in pregnancy, whereas an increase of disaccharidase activities per small intestine length normalized to body mass was observed in lactation.     

Serum lipoproteinemia in pregnant and lactating rats

Serum lipoproteins of pregnant and puerperal rats were studied by preparative and analytical ultracentrifugation. The concentration for the fraction with density less than 1.019 was markedly elevated in rats during the 3rd wk of gestation and in lactating rats. This fraction showed similar triglyceride fatty acid composition and immunoelectrophoretic behavior whether it was derived from pregnant or nonpregnant rats, and when partially delipidized, the lipoproteins from both groups showed similar immunoelectrophoretic characteristics and sedimentation rates. When lactation was interrupted during puerperium, serum lipoproteins returned to control levels; but in lactating rats, high levels of serum very low density lipoprotein persisted up to 3 wk post partum.     

Islet transplantation in diabetic pregnant rats normalizes glucose homeostasis in their offspring.

Diabetes of the mother during pregnancy induces alterations in the fetus, resulting in impaired glucose homeostasis in the offspring. In youngsters of severely diabetic mothers, during glucose infusion, hyperinsulinemia is associated with hyperresponsiveness of the beta-cells and insulin resistance. In order to normalize maternal metabolism, isolated islets from neonatal rats were transplanted into the vena porta of severely hyperglycemic (Streptozotocin) rats at day 15 of gestation. Strict glycemic control of the mothers was achieved throughout further gestation and lactation. In the adult offspring of these transplanted rats insulin levels during glucose infusion were significantly lower than in the offspring of sham-transplanted diabetic mothers and were not different from controls. The work confirms that the diabetic state of the mother during late gestation (the period of development of the endocrine pancreas and of the insulin-receptor system) is the inducing factor for the abnormal glucose homeostasis in the offspring, and normalisation of the hyperglycemia eliminates these long-term consequences.     

Oxidative stress and antioxidant defenses in pregnant women

Abstract

Objectives

Oxidative stress (OS) is defined as an imbalance in the production of reactive oxygen species and the capacity of antioxidant defenses. The objective of this work was to investigate OS and antioxidant capacity in pregnant women.

Methods

Parameters of the oxidative status and antioxidant capacity in serum and whole blood were evaluated in thirty-nine women with normal pregnancy.

Results

The assessment of antioxidants indicated an increase in superoxide dismutase and catalase activities (P < 0.05 and P < 0.01) and a decrease in ascorbic acid levels and the total content of sulfhydryl (P < 0.05 and P < 0.001). Additionally, when the pro-oxidant system was investigated we found an increase (P < 0.01) in malondialdehyde and no significant change (P > 0.05) in protein carbonylation.

Discussion

This study demonstrates that there is a change in the pro-oxidant and antioxidant defenses associated with body and circulation changes that are inherent to the pregnancy process.     

Effect of tryptophan on livers of pregnant and lactating rats and their fetuses and pups

The effect of the administration of L-tryptophan on hepatic polyribosomes and protein synthesis in pregnant rats and their fetuses and in lactating rats and their pups was investigated. Pregnant rats tube-fed tryptophan 1 hr before killing revealed increased hepatic protein synthesis but essentially unmodified polyribosomal aggregation of maternal livers while no changes were observed in fetal livers in comparison to controls (water-treated). Lactating rats tube-fed tryptophan 1 hr before killing revealed increased polyribosomal aggregation and protein synthesis of the livers in comparison to controls. Pups of these mothers that received tryptophan intraperitoneally 1 hr before killing did not reveal a significant change in the hepatic polyribosomes or protein synthesis.     

Effects of quercetin on predator stress-related hematological and behavioural alterations in pregnant rats and their offspring

This study aims at investigating the effect of a psychogenic stress during gestation on the behaviour and haematological indices in dams as well as on the neonatal haematological status and periadolescent behaviour in their offspring. Moreover, the ability of quercetin, a natural flavonoid, to prevent the stress-induced changes was estimated. Pregnant Wistar rats were pretreated with quercetin before the exposure to a predator stress on gestational day 19. Post-stress maternal anxiety-like behaviour was assessed with a concomitant haematological analysis. In the offspring, haematological analysis and behavioural testing were performed during the postnatal stage. Our results revealed that predator stress causes an anxiety-like behaviour in dams along with a decrease in erythrocytes, a microcytosis, and a thrombocytosis. Prenatally stressed neonates manifested microcytosis and thrombocytosis with a significant polycythemia. Signs of motor hyperactivity, anxiety-like behaviour, and memory dysfunction were detected at periadolescence. Quercetin pretreatment alleviated the stress-induced behavioural and haematological impairments in dams but failed to attenuate the haematological changes in neonates. A sex-dependent effect of quercetin on behaviour was found at periadolescence. Our findings suggest that, besides a beneficial effect on haematological and behavioural anomalies in traumatized dams, quercetin may lastingly modulate the behaviour of their progeny.     

Low-protein diet changes thyroid function in lactating rats

Lactating rats were fed with free access to an 8% protein-restricted diet (PR); the control group was fed a 23% protein diet (C). An energy-restricted (pair-fed) group was given the same food as the animals in the control group, but the amounts of food consumed by both PF and PR were about the same. The body weight and serum albumin concentration of PR and PF dams were significantly (P < 0. 05) lower than that of the controls. The PR group had a significant increase in serum-free triiodothyronine (FT3) concentration, 24-hr mammary gland and milk radioiodine (I131) uptake (67%, 278%, and 200%, respectively) as compared with the controls. On the other hand, those animals had a significantly lower serum-free thyroxine (FT4) concentration and 2- and 24-hr thyroid I131 uptake (67%, 64%, and 74%, respectively). Protein malnutrition during lactation did not alter thyroid or liver 5'-deiodinase activity significantly. However, PF dams had a significantly lower (25%) thyroid 5'-deiodinase activity. These data suggest that protein-restricted lactating dams had an adaptive change in the thyroid function, which could be important to increase the transference of iodine or triiodothyronine through the milk to their pups and prevent sequelae of neonatal hypothyroidism.     

Oxidative stress in the hippocampus after pilocarpine-induced status epilepticus in Wistar rats

The role of oxidative stress in pilocarpine-induced status epilepticus was investigated by measuring lipid peroxidation level, nitrite content, GSH concentration, and superoxide dismutase and catalase activities in the hippocampus of Wistar rats. The control group was subcutaneously injected with 0.9% saline. The experimental group received pilocarpine (400 mg.kg(-1), subcutaneous). Both groups were killed 24 h after treatment. After the induction of status epilepticus, there were significant increases (77% and 51%, respectively) in lipid peroxidation and nitrite concentration, but a 55% decrease in GSH content. Catalase activity was augmented 88%, but superoxide dismutase activity remained unaltered. These results show evidence of neuronal damage in the hippocampus due to a decrease in GSH concentration and an increase in lipid peroxidation and nitrite content. GSH and catalase activity are involved in mechanisms responsible for eliminating oxygen free radicals during the establishment of status epilepticus in the hippocampus. In contrast, no correlations between superoxide dismutase and catalase activities were observed. Our results suggest that GSH and catalase activity play an antioxidant role in the hippocampus during status epilepticus.     

Liver and kidney peroxisomes in lactating rats and their pups after treatment with ciprofibrate. Biochemical and morphometric analysis.

We administered the hypolipidemic drug ciprofibrate to lactating rats and examined the enzymatic content and ultrastructural features of liver and kidney peroxisomes, both in treated animals and in their pups. The peroxisomal morphometric parameters, in particular, were measured in specimens submitted to the cytochemical reaction for the marker enzyme catalase. In liver of treated rats, the activities of peroxisomal enzymes involved in the fatty acid catabolism were significantly increased, while D-amino acid oxidase activity was lower than in controls; increments were also found in relative volume and pleiomorphism degree of the peroxisomal compartment, where a catalase dilution was supposed to occur. In the kidney, the treatment induced generalized increases of all examined enzymes; values significantly higher than controls were found in peroxisomal relative volume and numerical density, while the peroxisomal mean diameter practically did not change. The two organs, moreover, were affected by the drug in an age-dependent way, the pups being more responsive than the adults. The organ- and age-specific responses to the drug are interpreted as possibly related to the tissue-specific distribution of the peroxisomal proliferator activated receptor isotypes.     

Oxidative stress and arachidonic acid mobilization

Reactive oxygen species are known to contribute to tissue damage during injury and inflammation. However, these species can also be sensed by the cells and trigger intracellular signaling cascades. This review examines recent evidence on the involvement of reactive oxygen species in lipid signaling. Attention is focused on activation of phospholipase A2s, enzymes whose action on membrane phospholipids can also render molecules with opposite effects on cells. The participation of Ca2+-dependent and Ca2+-independent phospholipase A2s in arachidonic acid mobilization from phospholipids is discussed, with particular attention to the interplay between cytosolic and secreted Ca2+-dependent forms. The involvement of alternative routes for arachidonic acid mobilization under oxidative stress is also considered.     

Oxidative stress in normal and diabetic rats.

Parameters related to oxidative stress were studied in a group of 10 Wistar diabetic rats and 10 control rats. The levels of total erythrocyte catalase activity in the diabetic animals were significantly (p<0.001) greater than the control levels. The diabetic animals presented an amount of vitamin E far greater (p<0.0001) than the controls, as was also the case for the vitaminE/polyunsaturated fatty acid (PUFA) and vitaminE/linoleic acid (C18:2) ratios. Greater vitaminE/triglyceride (TG) ratio, however, appeared in the control group. The corresponding vitamin A ratios (vitaminA/TG, vitaminA/PUFA, vitaminA/C 18:2) were higher in the control group. Our work corroborates the findings that fatty acid metabolism presents alterations in the diabetes syndrome and that the antioxidant status is affected.