M.L. Ojeda

Influence of cow or goat milk consumption on antioxidant defence and lipid peroxidation during chronic iron repletion

Despite Fe deficiency and overload having been widely studied, no studies are available about the influence of milk consumption on antioxidant defence and lipid peroxidation during the course of these highly prevalent cases. The objective of the present study was to assess the influence of cow or goat milk-based diets, either with normal or Fe-overload, on antioxidant defence and lipid peroxidation in the liver, brain and erythrocytes of control and anaemic rats after chronic Fe repletion. Weanling male rats were randomly divided into two groups: a control group receiving a normal-Fe diet (45 mg/kg) and an anaemic group receiving a low-Fe diet (5 mg/kg) for 40 d. Control and anaemic rats were fed goat or cow milk-based diets, either with normal Fe or Fe-overload (450 mg/kg), for 30 or 50 d. Fe-deficiency anaemia did not have any effect on antioxidant enzymes or lipid peroxidation in the organs studied. During chronic Fe repletion, superoxide dismutase (SOD) activity was higher in the group of animals fed the cow milk diet compared with the group consuming goat milk. The slight modification of catalase and glutathione peroxidise activities in animals fed the cow milk-based diet reveals that these enzymes are unable to neutralise and scavenge the high generation of free radicals produced. The animals fed the cow milk diet showed higher rates of lipid peroxidation compared with those receiving the goat milk diet, which directly correlated with the increase in SOD activity. It was concluded that goat milk has positive effects on antioxidant defence, even in a situation of Fe overload, limiting lipid peroxidation.

Circulating Inflammatory Mediators during Start of Fever in Differential Diagnosis of Gram-Negative and Gram-Positive Infections in Leukopenic Rats

ABSTRACT Gram-negative and gram-positive infections have been considered the most important causes of morbidity and mortality in patients with leukopenia following chemotherapy. However, discrimination between bacterial infections and harmless fever episodes is difficult. Because classical inflammatory signs of infection are often absent and fever is frequently the only sign of infection, the aim of this study was to assess the significance of serum interleukin-6 (IL-6), IL-10, macrophage inflammatory protein-2 (MIP-2), procalcitonin (PCT), and C-reactive protein (CRP) patterns in identifying bacterial infections during start of fever in normal and cyclophosphamide-treated (leukopenic) rats following an injection of lipopolysaccharide (LPS) or muramyl dipeptide (MDP) as a model for gram-negative and gram-positive bacterial infections. We found that, compared to normal rats, immunosuppressed animals exhibited significantly higher fevers and lesser production of all mediators, except IL-6, after toxin challenge. Moreover, compared to rats that received MDP, both groups of animals that received an equivalent dose of LPS showed significantly higher fevers and greater increase in serum cytokine levels. Furthermore, in contrast to those in immunocompetent rats, serum levels of IL-6 and MIP-2 were not significantly changed in leukopenic animals after MDP injection. Other serum markers such as PCT and CRP failed to discriminate between bacterial stimuli in both groups of animals. These results suggest that the use of the analyzed serum markers at an early stage of fever could give useful information for the clinician for excluding gram-negative from gram-positive infections.

Dietary selenium plus folic acid as an antioxidant therapy for ethanol-exposed pups.

BACKGROUND Nutrients such as folic acid and selenium are decreased in dams exposed to ethanol during gestation and lactation, affecting their metabolism, antioxidant balance, and the future health of their progeny. We will study whether the supplementation of the maternal diet with folate and selenium can prevent ethanol-induced oxidative liver disorders in the offspring. METHODS Dams were randomised into four groups: control, alcohol, alcohol+folic acid+Se, and control+folic acid+Se. We determined selenium by graphite-furnace atomic absorption and antioxidant enzyme activities, lipid peroxidation, and protein carbonyl by spectrophotometry in the offspring. RESULTS Alcohol increased serum Se levels and glutathione peroxidase (GPx) activity. However, in the liver of pups from ethanol-exposed dams a decrease in selenium was provoked and GPx activity increased with the double supplementation. Glutathione reductase (GR) and catalase (CAT) activities increased with ethanol, while double supplementation significantly decreased the GR activity. The supplemented diet reduced the protein peroxidation found in ethanol pups. CONCLUSIONS These results suggest that folic acid+Se could be effective in neutralising the damage of ethanol consumption in pups since it prevents peroxidation protein products.

Ethanol Consumption by Wistar Rat Dams Affects Selenium Bioavailability and Antioxidant Balance in Their Progeny

Ethanol consumption affects maternal nutrition, the mothers’ antioxidant balance and the future health of their progeny. Selenium (Se) is a trace element cofactor of the enzyme glutathione peroxidase (GPx). We will study the effect of ethanol on Se bioavailability in dams and in their progeny. We have used three experimental groups of dams: control, chronic ethanol and pair-fed; and three groups of pups. Se levels were measured by graphite-furnace atomic absorption spectrometry. Serum and hepatic GPx activity was determined by spectrometry. We have concluded that ethanol decreased Se retention in dams, affecting their tissue Se deposits and those of their offspring, while also compromising their progeny’s weight and oxidation balance. These effects of ethanol are caused by a reduction in Se intake and a direct alcohol-generated oxidation action.

Oral or intraperitoneal binge drinking and oxidative balance in adolescent rats.

Oxidative imbalance is one of the most important mechanisms of alcohol-induced injury. Acute alcohol exposure induces a significant amount of reactive oxygen species during its hepatic metabolism via the microsomal ethanol oxidizing system. During adolescence, the physiological development is still taking place; therefore, ethanols effects differ in adolescents compared to that in adults. Because binge drinking is the most important model of ethanol intake used by adolescents and because little is known about its effects on the liver, we have used two routes of acute ethanol administration (oral and intraperitoneal) in adolescent rats in order to analyze the oxidative damage caused in the periphery and liver. Here, it has been demonstrated for the first time that binge drinking in adolescents causes peripheral oxidation of lipid and DNA as well as lipid and protein hepatic oxidation, which are related to lower glutathione peroxidise (GPx) activity, higher catalase (CAT) activity, and higher expression of NADPHoxidase, contributing to hepatic damage. In addition, it is shown that the intraperitoneal administration route results in increased oxidative damage, which is probably related to the resulting general stress response that causes higher DNA and protein oxidation due to higher NADPHoxidase expression and higher CAT and superoxide dismutase (SOD) activities. According to these results, it is concluded that binge drinking induces hepatic damage during adolescence, at least in part, as consequence of oxidative stress because the antioxidant response was insufficient to avoid liver oxidation. Alcohol administered intraperitoneally provoked more DNA oxidation than that from the oral alcohol exposure model.

Oxidative effects of chronic ethanol consumption on the functions of heart and kidney: folic acid supplementation.

AIMS The principal aim of this study was to investigate the oxidative effects of chronic ethanol consumption on the functions of the heart and the kidney and the possible modification of this effect by folic acid supplementation. Moreover, in order to find whether this oxidative profile affects cardiovascular function, parameters such as heart rate and glomerular filtration rate were also assessed. METHODS Four experimental groups of rats were used: control, ethanol-exposed, control supplemented with folic acid and ethanol-exposed plus folic acid. Ethanol-exposed rats were subjected to a chronic ethanol treatment (2 months), in which the level of alcohol reaches 30% v/v. Diet and ethanol solution were provided ad libitum, and folic acid supplementation was 8 vs. 2 ppm. Energy intake, creatinine clearance and heart rate were determined. Antioxidant enzyme activity and lipid and protein peroxidation of the kidney and the heart were measured by the spectrophotometric method. RESULTS Ethanol increases heart size and catalase (CAT) activity and decreases lipid peroxidation in heart without changing heart rate. However, in the kidney, ethanol decreases CAT activity, increases lipid peroxidation and decreases glomerular filtration rate. Folic acid supplementation avoids these situations; it does not, however, improve glomerular function. CONCLUSION Chronic ethanol consumption has many effects on the antioxidant enzymatic activity of the heart and the kidney, leading to increased renal lipid peroxidation prevented by folic acid supplementation.

Identification and localization of procalcitonin-like immunoreactivity in the rat hypothalamus

Procalcitonin (PCT) is a 116-amino acid polypeptide physiologically produced, as the precursor protein of calcitonin (CT), in the parafollicular cells of the thyroid gland, but physiological functions and other major sources of PCT remains unclear. The distribution of PCT-like immunoreactivity (PCT-LI) in the rat hypothalamus was examined by immunohistochemistry using a monoclonal antibody raised against the mid-region of human PCT (60-77-amino acid fragment). This antibody cross-reacts well with rat PCT and immature CT, but it cross-react poorly with free mature CT. Abundant expression of PCT-LI was found in zones at the interface between brain and cerebrospinal fluid (CSF) such as the ependymal layer and ventral glia limitans (VGL). Double labeling of PCT and glial fibrillary acidic protein (GFAP) identified this population of small cells as astrocytes, possibly tanycytes, a type of specialized glial cell that interacts in neuroendocrine functional dynamics. The fibers of these cells extend to circumventricular organs (CVOs) and to astrocytes located inside the parenchyma of key autonomic regulatory hypothalamic areas, with highest densities in the supraoptic nucleus (SO), arcuate nucleus (Arc), area postrema (AP), median eminence (ME), medial preoptic nucleus, tuber cinereum, and accessory neurosecretory nuclei. No strongly labeled cells were found in the paraventricular nucleus. The wide distribution of PCT-LI in the hypothalamus, in close correspondence with previous mapping of CT receptors in the rat brain, suggests that PCT may influence a multitude of biological activities associated with the hypothalamic-pituitary axis.

Selenium Dietary Supplementation and Oxidative Balance in Alcoholism

Alcohol consumption causes major health and addiction problems that are the consequence of toxic compounds produced primarily by its oxidative metabolism at a hepatic level. The liver, therefore, is the main tissue exposed to this drug, but other tissues are also affected. Selenium (Se) is an essential trace mineral, fundamental to health because it presents antioxidant properties, and forms part of selenoproteins, such as glutathione peroxidase. Alcohol intake decreases Se deposits in the organism, as well as selenoproteins’ expressions and activity, exacerbating the problems induced by alcoholism. The aim of this chapter is to collect relevant information and data to support evidence on ethanol consumption and Se absorption and bioavailability in the organism, as well as its relationship with selenoproteins and oxidative stress. The role of dietary Se supplementation, as a means of acting against the adverse effects provoked by alcohol, emphasizing its action on oxidative balance, is also analyzed.

The Benefits of Administering Folic Acid in Order to Combat the Oxidative Damage Caused by Binge Drinking in Adolescent Rats

AIMS An important mechanism in alcohol-induced injury is biomolecular oxidative damage. Folic acid is supplied to chronic alcoholic patients in order to prevent this situation, as this is the main vitamin deficiency that they suffer from. Acute alcohol exposure, such as binge drinking, is one of the most widespread ethanol consumption models practiced by adolescents. However, there is no evidence of folic acid body profiles after this pattern of consumption. METHODS Four groups of adolescent rats were used: control, alcohol (exposed to intraperitoneal binge drinking), control folic acid-supplemented group and alcohol folic acid-supplemented group. Folic acid levels, protein, lipid and DNA oxidative damage in serum, and liver glutathione (GSH) and reduced/oxidized glutathione ratio (GSH/GSSG) were measured. RESULTS Binge-drinking rats had higher lipids and DNA oxidation levels. They also had lower hepatic GSH levels and GSH/GSSG ratio. Folic acid supplementation to binge-drinking rats does not change the serum protein oxidation but decreases lipid and DNA oxidation. Finally, GSH increased to control levels with folic acid supplementation. CONCLUSION Folic acid supplementation is an economic and efficient therapy against the oxidative damage in lipids and mainly in DNA stability caused by binge drinking during adolescence. It has also been demonstrated that folic acid increases GSH levels, improving the antioxidant status and revealing a hepatoprotective effect during binge drinking.

Se bioavailability and glutathione peroxidase activity in iron deficient rats.

Little information is available on the relationship of Se deposit in target organs and GPx activity in iron deficiency anemia. As red blood cells (RBCs) play a crucial role on Se metabolism and during Fe deficiency anemia a lower count of RBCs is featured, we aimed to investigate the influence of this pathology on Se bioavailability and the relationship with antioxidant status. 20 male Wistar rats were randomly divided into two groups, a control group receiving AIN-93G diet with normal Fe content (45mg/kg diet) and the Fe-deficient group receiving AIN-93G diet with low Fe content (5mg/kg diet) for 40 days. Both diets were prepared with an adequate Se content (0.180mg/kg diet). The digestive and metabolic utilization of Se, the distribution in target organ, the GPx activity and TBARS production were measured after receiving the diets. Se retention increased (P<0.001) in the anemic group, fact that contributes to keep the enzymatic antioxidant activity of GPx in normal levels and the tendency observed is that stored Se increased in the organs, especially in kidney (P<0.01), however, a lower Se deposit was found in sternum of anemic rats (P<0.001). The lower count of RBCs featured in this pathology (P<0.001) causes a decrease of Se concentration in sternum meanwhile the increase in kidney deposit is a consequence of the lower urinary losses (P<0.001).