Lipid peroxidation in mitochondria and microsomes from adult and fetal rat tissues. Effects of Zn deficiency, Fe, and salicylate

Abortion-prone mating influences placental antioxidant status and adversely affects placental and foetal development

Oxidative stress is associated with decreased female fertility and adversely affects prenatal development. Mammalian cells have developed a network of enzymatic and non-enzymatic antioxidant defence systems to prevent oxidative stress. Little attention has been paid to the antioxidative pathways in placentas of normal and disturbed pregnancies, leaving a gap in our knowledge about the role of antioxidants in the control of foeto-placental development. The challenges in studying early human pregnancy can partly be overcome by designing animal models of abnormal pregnancy. We aimed to determine whether the antioxidant status of placentas from the CBA/J × DBA/2 abortion-prone pregnant mice differed from that of normal pregnant mice. The foetal/placental weight ratio was lower in abortion-prone matings compared with that in non-abortion-prone matings. The increased placental malondialdehyde (MDA) content, the end products of lipid peroxidation, with concomitants alterations in placental antioxidants, namely copper-zinc containing superoxide dismutase (SOD1), manganese containing (SOD2), glutathione peroxidases (GPX), glutathione reductase (GR) and catalase (CAT) activities may be involved in placental and foetal growth restriction. We show that placental oxidative stress is linked with poor prenatal development and pregnancy losses in CBA/J × DBA/2 mice matings. This animal model may be useful in the evaluation of nutritional antioxidant therapies for oxidative stress and associated prenatal developmental disorders.

The use of whole embryo culture to elucidate teratogenic mechanisms

In the overview presented, only selected examples for the applicability of whole embryo culture, and a few examples for its use and possible misuse, are mentioned. In general, the system has proved suitable for elucidating mechanisms involved in abnormal development at this embryonic stage. However, it should be remembered that only a small window of prenatal development can be judged with this technique, and that the system is not well suited for elucidating many special effects and abnormalities induced at later stages of development. For this reason, no single in vitro system is suitable to study all kinds of problems in prenatal biology or toxicology. As emphasized before, the real significance of the whole embryo culture technique rests on the variety of methodological possibilities that can be modified by any creative scientist. In connection with in vivo and appropriate pharmacokinetic studies, this system will play an important role in the field of developmental biology and toxicology in the future.

Smoking and inflammatory bowel diseases: what in smoking alters the course?

Epidemiological studies provide strong evidence to confirm the correlation between cigarette smoking and inflammatory bowel diseases. This relationship is proved to be positive in Crohn's disease and negative in ulcerative colitis. What in smoking alters the course of inflammatory bowel diseases is still a mystery. Different smoking parts have different and may be opponent actions. Smoking has dual effects. Some of its activities are, sometimes, constructive as they are working in an antagonistic manner to the mechanism of the disease, such as reducing rectal blood flow and accordingly less recruitments of inflammatory mediators to the area of inflammation, enhancement of mucosal production, and consequently, strengthening the membranes, and inhibition of pro-inflammatory mediators' liberation and activity in subjects with ulcerative colitis. Yet the outcome of smoking actions may be affected by the existence of other cofactors. Odd factors, such as shortage of zinc in subjects with Crohn's disease, may facilitate liberation of pro-inflammatory mediators and their activities and accordingly exacerbates symptoms.

Salicylic acid-induced hepatotoxicity triggered by oxidative stress

Salicylic acid is a widely used nonsteroidal anti-inflammatory drug (NSAID). But it is known to cause serious liver damage occasionally. Mitochondrial dysfunction and oxidative stress are predicted to be the major factors of salicylic acid-induced liver injury. We investigated the influence of salicylic acid on ATP contents, oxygen consumption and lipid peroxidation in the presence of the same concentration of salicylic acid. Leakage of lactate dehydrogenase (LDH) was significantly higher in the presence of 5mM salicylic acid than in its absence. Salicylic acid-induced thiobarbituric acid-reactive substance (TBARS) formation and spontaneous chemiluminescence (CL) in rat hepatocytes, whereas antioxidants, such as promethazine (PMZ) and N,N-diphenylphenylenediamine (DPPD), suppressed both TBARS formation and LDH leakage. TBARS formation in rat liver microsomes was suppressed by diethyldithiocarbamate (a specific inhibitor of cytochrome P450 (CYP)2E1) and diclofenac (a specific inhibitor of CYP2C11). These results suggest that salicylic acid-induced lipid peroxidation was related to oxidative metabolism mediated by CYP2E1 and CYP2C11. On the other hand, 5mM salicylic acid induced a drastic decrease of ATP contents in rat isolated hepatocytes. Furthermore, mitochondrial respiration control ratio (RC ratio), calculated by State 3/State 4 also decreased with the increase of salicylic acid concentration. These findings suggest that salicylic acid would trigger mitochondrial dysfunction and cause ATP decrease, leading to lethal liver cell injury by lipid peroxidation, although this hypothesis remains to be elucidated in vivo.

Dietary zinc deficiency induced-changes in the activity of enzymes and the levels of free radicals, lipids and protein electrophoretic behavior in growing rats

Zinc (Zn) is an essential nutrient that is required in humans and animals for many physiological functions, including immune and antioxidant function, growth and reproduction. The present study was conducted to investigate the effects of adequate Zn level (38 mg/kg diet, as a control) and two low levels that create Zn deficiencies (19 mg/kg diet, 1/2 of the control and 3.8 mg/kg diet, 1/10 of the control) in growing male and female rats for 10 weeks. To evaluate the effects of these levels, the concentrations of thiobarbituric acid-reactive substances (TBARS), biochemical parameters and protein pattern were studied. Lipid peroxidation in liver, brain and testes of rats fed Zn-deficient diet was indicated by increased TBARS. Serum, liver, brain and testes glutathione S-transferase (GST) activities were significantly (P<0.05) increased in Zn-deficient rats, the effect was pronounced in rats fed the lowest level of Zn (1/10 of control). The activity of lactate dehydrogenase (LDH) was significantly (P<0.05) increased in liver, brain and testes, but decreased in serum in a dose-dependent manner. Zinc deficiency increased (P<0.05) liver aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in a dose-dependent manner, while there was no effect on the activity of these enzymes in testes. Zinc deficiency resulted in a significant (P<0.05) decrease in the activity of alkaline phosphatase (AlP) in serum and liver in a dose-dependent manner, but no effect in testes was found. The activity of acid phosphatase (AcP) was not affected in serum, liver and testes. Zn-deficient rats had higher liver concentrations of total lipids (TL), cholesterol, triglyceride (TG), and low density lipoprotein (LDL), while high density lipoprotein (HDL) was significantly (P<0.05) declined in a dose-dependent manner. Brain and serum acetylcholinesterase (AChE) activities were, however, not affected (P<0.05) by Zn deficiency. Protein content in liver, brain and testes showed a significant (P<0.05) decrease in rats fed the lowest level of Zn (1/10 of control). Polyacrylamide gel electrophoresis (native-PAGE) of serum proteins revealed that the intensity of immunoglobulins, serum albumin as well as several peptide bands were decreased in rats fed 1/2 or 1/10 of Zn adequate, i.e. their synthesis was affected and it was pronounced with the lowest level of Zn deficiency (1/10 of control). However, no clear effect on the transferrin was observed in both cases compared to controls. From the results of this study it can be concluded that Zn deficiency exerts numerous alterations in the studied biochemical parameters, protein pattern, and increased lipid peroxidation.

Effect of dietary zinc on lipid peroxidation, glutathione, protein thiols levels and superoxide dismutase activity in rat tissues

Dietary zinc deficiency can cause increased lipid peroxidation while zinc supplementation inhibited this process. The aim of this study was to investigate the effect of dietary zinc on malondialdehyde (MDA) product as an index of endogenous lipid peroxidation, glutathione (GSH) and protein thiols (PrSHs) as well as superoxide dismutase (SOD) activity in rat blood, liver and pancreas. Young male rats were fed a zinc deficient (ZD) basal diet containing congruent to 0.5 ppm zinc or were fed ad libitum (AL) a zinc adequate diet (30 ppm zinc) for 3 weeks. The ZD rats were then fed the basal diet supplemented with either 100 ppm zinc or 1000 ppm zinc for another 3 weeks. The zinc concentration of the investigated tissues reflected the dietary zinc content. Plasma, liver and pancreas MDA measurements from ZD rats revealed significant increases (P < 0.05, < 0.001) as compared to AL control values, the highest increase was in pancreas. ZD rats also displayed significant decreases in their blood and liver GSH content (P < 0.001, < 0.05) and SOD activity (P < 0.001) as well as serum PrSHs (P < 0.001) as compared to AL control values. However, these measurements in pancreas were insignificantly changed except GSH content was significantly increased (P < 0.05). Feeding ZD rats a diet containing 100 ppm or 1000 ppm zinc resulted in a significant reduction of the endogenous MDA formation (P < 0.05, < 0.001) in their tissues with the reversal of changes in the other parameters, so that their levels were nearly restored to AL control values especially in response to 1000 ppm zinc.(ABSTRACT TRUNCATED AT 250 WORDS)

Zinc deficiency does not enhance LDL uptake by P 388 D1 macrophages in vitro

The aim of the study was to investigate the effect of zinc depletion on the susceptibility of Wistar rat low-density lipoproteins (LDL) to peroxidation and their uptake by macrophages, before and after in vitro oxidation. The rats were fed for 7 wk a Zn-adequate diet (100 ppm) ad libitum (AL), a Zn-deficient diet (0.2 ppm) ad libitum (ZD), or a Zn-adequate diet according to the pair-feeding method (PF). Zinc status was determined and, for each group, blood was pooled, and LDS were isolated and labeled with 125Iodine. An aliquot of each LDL sample was oxidized using FeII 10 microM/ascorbate 250 microM. Oxidized and nonoxidized (native) LDL were incubated with P 388 D1 macrophages, and their rates of uptake and degradation by macrophages were measured. Before oxidation, LDL uptake and degradation were not modified by the diet, suggesting that Zn deficiency did not modify rat LDL in vivo. After oxidation, both LDL uptake and degradation were significantly enhanced in the three groups. Nevertheless, we did not observe a significant effect of Zn deficiency. This observation suggests that, in our experimental conditions, Zn deficiency did not modify LDL catabolism.

Protection against salicylate-induced hepatic injury by zinc. A histochemical and biochemical study

Female Wistar rats received an oral dose of 700 mg salicylic acid/kg body wt., given as sodium salicylate. Some of the salicylate-treated rats received two subcutaneous injections of 100 mumol kg-1 ZnCl2 (24 h before and simultaneously with the salicylate administration). Other animals were given one subcutaneous injection of 100 mumol kg-1 ZnCl2 simultaneously with the salicylate treatment. Control rats were similarly injected with ZnCl2. Twenty four hours after salicylate treatment, serum and livers were taken for histochemical and biochemical analysis. The most remarkable effects of the treatment were enrichment of lipid droplets and iron and a reduction of glycogen, particularly in the periportal hepatocytes. The effects of salicylate were partially prevented by two ZnCl2 injections. The protective effects of ZnCl2 may be due to lower iron uptake into hepatocytes and by the induction of zinc metallothionein, which can serve as a scavenger for oxygen radicals.