Carmen M. Vázquez

Effects of dietary fats (fish, olive and high-oleic-acid sunflower oils) on lipid composition and antioxidant enzymes in rat liver

The effects of two oleic-acid-rich diets (containing olive oil, OO, and high-oleic-acid sunflower oil, HOSO) on plasma and liver lipid composition detoxification enzyme activities, were compared with those of a fish-oil (FO) diet and a control diet. Compared with the control diet, plasma and hepatic total triacylglycerol concentrations were increased in the animals fed on the HOSO and OO diets and decreased in those fed on the FO diet. The animals fed on FO showed the highest level of cholesterol in the liver and had lower plasma cholesterol concentrations when compared with those fed on the two oleic-acid-rich diets. In comparison with the animals fed on the diets enriched in oleic acid, the FO group showed higher hepatic levels of polyunsaturated fatty acids of the n-3 series and lower levels of fatty acids of the n-6 series. Livers of FO-fed rats, compared with those of OO- and HOSO-fed rats showed: (1) significantly higher activities of catalase (EC 1.11.1.6) glutathione peroxidase (EC 1.11.1.9) and Cu/Zn superoxide dismutase (EC 1.15.1.1); (2) no differences in the NADPH-cytochrome c reductase (EC 1.6.99.3) activity. The HOSO diet had a similar effect on liver antioxidant enzyme activities as the OO diet. In conclusion, it appears that changes in the liver fatty acid composition due mainly to n-3 lipids may enhance the efficiency of the antioxidant defence system. The two monounsaturated fatty acids oils studied (OO and HOSO), with the same high content of oleic acid but different contents of natural antioxidants, had similar effects on the antioxidant enzyme activities measured.

Captopril reduces cardiac inflammatory markers in spontaneously hypertensive rats by inactivation of NF-kB.

BackgroundCaptopril is an angiotensin-converting enzyme (ACE) inhibitor widely used in the treatment of arterial hypertension and cardiovascular diseases. Our objective was to study whether captopril is able to attenuate the cardiac inflammatory process associated with arterial hypertension.MethodsLeft ventricle mRNA expression and plasma levels of pro-inflammatory (interleukin-1β (IL-1β) and IL-6) and anti-inflammatory (IL-10) cytokines, were measured in spontaneously hypertensive rats (SHR) and their control normotensive, Wistar-Kyoto (WKY) rats, with or without a 12-week treatment with captopril (80 mg/Kg/day; n = six animals per group). To understand the mechanisms involved in the effect of captopril, mRNA expression of ACE, angiotensin II type I receptor (AT1R) and p22phox (a subunit of NADPH oxidase), as well as NF-κB activation and expression, were measured in the left ventricle of these animals.ResultsIn SHR, the observed increases in blood pressures, heart rate, left ventricle relative weight, plasma levels and cardiac mRNA expression of IL-1β and IL-6, as well as the reductions in the plasma levels and in the cardiac mRNA expression of IL-10, were reversed after the treatment with captopril. Moreover, the mRNA expressions of ACE, AT1R and p22phox, which were enhanced in the left ventricle of SHR, were reduced to normal values after captopril treatment. Finally, SHR presented an elevated cardiac mRNA expression and activation of the transcription nuclear factor, NF-κB, accompanied by a reduced expression of its inhibitor, IκB; captopril administration corrected the observed changes in all these parameters.ConclusionThese findings show that captopril decreases the inflammation process in the left ventricle of hypertensive rats and suggest that NF-κB-driven inflammatory reactivity might be responsible for this effect through an inactivation of NF-κB-dependent pro-inflammatory factors.

The role of inflammatory markers in the cardioprotective effect of L-carnitine in L-NAME-induced hypertension.

BACKGROUND The mechanism(s) underlying the effects of L-carnitine (beta-hydroxy-gamma-N-trimethylammonium-butyrate; LC) in cardiovascular diseases are not well clarified. Previous studies have demonstrated that oxidative stress and inflammation contribute to arterial hypertension, and antioxidant and/or anti-inflammatory therapies have been proposed. We hypothesized that LC might attenuate the hypertensive status through an inhibition of inflammation process. METHODS Heart mRNA expression and plasma levels of inflammatory markers, interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha), were measured in rats that were made hypertensive with N(omega)-nitro-L-arginine methyl ester (L-NAME) and subjected to a simultaneous administration of LC. To clarify the role of the renin-angiotensin system (RAS) in this effect of LC, the activity and expression of angiotensin I-converting enzyme (ACE) as well as the expression of angiotensin II type I receptor (AT1R) in the heart were also determined. RESULTS LC produced a significant, but not complete, reduction of blood pressure in L-NAME-treated rats. Plasma levels and heart expression of IL-1 beta, IL-6, and TNF-alpha showed an increase in the L-NAME group, which was reversed by LC treatment. The plasma ACE activity was not modified between normotensive and hypertensive rats although LC treatment produced a reduction of these values in the latter. Finally, protein and mRNA expression of ACE and AT1R was enhanced in the heart of L-NAME-treated animals, and LC reversed these values. CONCLUSIONS The chronic administration of LC reduces blood pressure and attenuates the inflammatory process associated with arterial hypertension. LC might produce a partial inactivation in the RAS resulting in a reduction in the production and effects of angiotensin II.

Comparative effects of captopril and l-carnitine on blood pressure and antioxidant enzyme gene expression in the heart of spontaneously hypertensive rats

It has been shown that oxidative stress is involved in the pathogenesis of arterial hypertension. The aim of this work was to study and compare the molecular mechanisms of the antioxidant properties of l-carnitine and captopril in spontaneously hypertensive rats (SHR). Antioxidant enzyme activity/regulation (glutathione peroxidase, glutathione reductase and superoxide dismutase) was measured in the erythrocytes and hearts of SHR. The molecular expression of endothelial nitric oxide synthase (eNOS), NADPH oxidase, angiotensin converting enzyme (ACE), angiotensin II type I receptor (AT(1) receptor) and NF-kappaB/IkappaB system was also measured in the hearts of these animals. Both l-carnitine and captopril augmented the antioxidant defense capacity in SHRs. This effect was mediated by an upregulation of antioxidant enzymes, an increase in the plasma total antioxidant capacity and a reduction of lipid peroxidation and superoxide anion production in the heart. The administration of both compounds to hypertensive animals also produced an upregulation of eNOS and a normalization of ACE, angiotensin AT(1) receptor, and the NF-kappaB/IkappaB system expression. In addition, captopril reduced the arterial blood pressure and the relative heart weights back to control values, whereas l-carnitine caused only a partial reduction of blood pressure values and did not alter the cardiac hypertrophy found in SHRs. In conclusion, we have found that l-carnitine and captopril have a similar antioxidant effect in the hearts of hypertensive rats. The molecular regulation of antioxidant enzymes through an inhibition of the renin-angiotensin system and a modulation of the NF-kappaB/IkappaB system seems to be responsible for this antioxidant effect.

Influence of microcystin-LR on the activity of membrane enzymes in rat intestinal mucosa.

The objective of the present study was to evaluate the effects of microcystin-LR (MCLR) on the activity of membrane enzymes from intestinal mucosa. In addition, serum chemistry and peroxidative status of both serum and intestinal homogenate were evaluated after treatment with MCLR. Wistar rats were treated with intraperitoneal injection of either 100 μg pure MCLR/Kg body weight or saline solution. A significant increase in liver weight and altered serum enzyme activities were found in MCLR-treated rats, indicating damage to the liver in these rats, as previously suggested. A higher specific activity of sucrase (1.5-fold) was observed after the administration of MCLR, whereas other intestinal apical membrane enzymes, such as lactase, maltase and alkaline phosphatase were not modified by the treatment. The specific activities of acid phosphatase and succinate dehydrogenase, markers for lysosomal and mitochondrial membranes, respectively, were also increased (32% and 60%, respectively) in treated rats. The analysis of lipid peroxidation showed that the peroxidative status was increased in both serum and intestinal mucosa from MCLR-treated rats, reflecting an excess production of oxygen free radicals induced by this cyanobacterial toxin. In conclusion, this study shows that acute exposure to MCLR affects the intestinal physiology by modifying the intestinal peroxidation status as well as the activity of membrane enzymes.ResumenEn este trabajo se analiza la acción de la toxina microcistina-LR (MCLR) sobre la actividad de diversas enzimas de membrana en la mucosa intestinal. Para ello, se utilizan ratas Wistar a las que se inyecta por vía intraperitoneal 100 μg MCLR/Kg peso corporal o bien solución salina (grupo control). Asimismo, se realiza un estudio bioquímico en suero, y se determina el grado de peroxidación lipídica en la mucosa intestinal y suero de estos animales tras el tratamiento con MCLR. La toxina induce daño hepático severo en las ratas tratadas, como lo demuestra el aumento del peso del hígado y diversas alteraciones de las enzimas hepáticas en suero. Por lo que respecta a las enzimas de membrana, las ratas tratadas con MCLR presentan un aumento en la actividad de la enzima sacarasa en la mucosa intestinal, no alterándose otras enzimas apicales como la lactasa, maltasa o fosatasa alcalina. MCLR también produce un aumento en la actividad de la fosfatasa ácida y succinato deshidrogenasa, marcadores respectivos de membranas lisosomales y mitocondriales. Además, los niveles de peroxidación lipídica en suero y mucosa intestinal aparecen anormalmente elevados tras el tratamiento, como consecuencia de la producción excesiva de radicales libres de oxígeno inducida por la toxina. Por consiguiente, la intoxicación aguda con MCLR afecta a la fisiología intestinal provocando una modificación del estado peroxidativo y alterando la actividad de las enzimas de membrana intestinales.

Comparative Effects of Feeding Different Fats on Fatty Acid Composition of Major Individual Phospholipids of Rat Hearts

Comparative effects of feeding dietary linoleic (corn oil), oleic (olive oil), alpha-linolenic (soybean oil) and polyunsaturated fatty acids (fish oil) on lipid content and fatty acid composition of major individual phospholipids of rat hearts were examined. Feeding different diets did not result in lipid accumulation in the heart. Total triglyceride, nonesterified fatty acid, cholesteryl ester and phospholipid levels of heart tissue were not affected by the type of dietary fatty acid. However, heart free cholesterol levels decreased in both animals fed the olive and the fish oil diets. The percentage of individual phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and cardiolipin (CL) did not modify by changes in the dietary fat composition. Heart tissue from animals fed on olive oil were enriched with 18:1 (n-9 + n-7) fatty acid in all phospholipid fractions. Animals fed corn oil contained higher proportions of 18:2 (n-6) for PC, PE and CL, and the ingestion of the soybean oil diet increased 18:2 (n-6) for PC and CL in the same proportion as the ingestion of the corn oil diet. The levels of 22:6 (n-3) were increased in the fish oil-fed group, accompanied by both a decrease in total (n-6) fatty acids and an increase in total (n-3) fatty acids in the three phospholipid fractions. The 20:5 (n-3) was only detected in these animals. These results show that olive oil is as effective as fish oil in reducing heart cholesterol content and support earlier works suggesting the role of fish oil in preventing cardiovascular disease.

L-Carnitine protects against arterial hypertension-related cardiac fibrosis through modulation of PPAR-γ expression.

Cardiac fibrosis is a pathogenic factor in a variety of cardiovascular diseases and is characterized by an abnormal accumulation of extracellular matrix protein that leads to cardiac dysfunction. l-Carnitine (LC) plays an essential role in the β-oxidation of long-chain fatty acids in lipid metabolism. We have previously demonstrated the beneficial effects of LC in hypertensive rats. The aim of this study was to analyze the effect of LC on arterial hypertension-associated cardiac fibrosis and to explore the mechanisms of LC action. To this end, four groups of rats were used: Wistar (control), rats treated with 400mg/kg/day of LC, rats treated with 25mg/kg/day of l-NAME (to induce hypertension), and rats treated with LC+l-NAME simultaneously. We found an elevation in the myocardial expression of profibrotic factors (TGF-β1 and CTGF), types I and III of collagen, and NADPH oxidase subunits (NOX2 and NOX4), in hypertensive rats when compared with normotensive ones. In addition, an increase in myocardial fibrosis was also found in the l-NAME group. These results were accompanied by a down-regulation of PPAR-γ in the heart of hypertensive animals. When hypertensive rats were treated with LC, all these alterations were reversed. Moreover, a significant negative correlation was observed between myocardial interstitial fibrosis and mRNA expression of PPAR-γ. In conclusion, the reduction of cardiac fibrosis and the down-regulation of NOX2, NOX4, TGF-β1 and CTGF induced by LC might be, at least in part, mediated by an upregulation of PPAR-γ, which leads to a reduction on hypertension-related cardiac fibrosis.

Liver Lipid Composition and Antioxidant Enzyme Activities of Spontaneously Hypertensive Rats after Ingestion of Dietary Fats (Fish, Olive and High-Oleic Sunflower Oils)

Hypertension is associated with greater than normal lipoperoxidation and an imbalance in antioxidant status, suggesting that oxidative stress is important in the pathogenesis of this disease. Although many studies have examined the effect of antioxidants in the diet on hypertensión and other disorders, less attention has been given to the evaluation of the role of specific dietary lipids in modulating endogenous antioxidant enzyme status. Previously, we have described that liver antioxidant enzyme activities may be modulated by consumption of different oils in normotensive rats. The purpose of the present study was to examine the effects of feeding different lipidic diets (olive oil, OO, high-oleic-acid sunflower oil, HOSO, and fish oil, FO) on liver antioxidant enzyme activities of spontaneously hypertensive rats (SHR). Plasma and liver lipid composition was also studied. Total triacylglycerol concentration increases in plasma and liver of animals fed on the HOSO and OO diets and decreases in those fed on the FO diet, relative to rats fed the control diet. The animals fed on the oil-enriched diet show similar hepatic cholesterol and phospholipid contents, which are higher than the control group. Consumption of the FO diet results in a decrease in the total cholesterol and phospholipid concentration in plasma, compared with the high-oleic-acid diets. In liver, the FO group show higher levels of polyunsaturated fatty acids (PUFA) of the (n-3) series, in relation to the animals fed on the diets enriched in oleic acid. Livers of FO-fed rats, compared with those of OO- and HOSO-fed rats showed: (i) significantly higher activities of catalase, glutathione peroxidase and Cu/Zn superoxide dismutase; (ii) no differences in the NADPH-cytochrome c reductase activity. The HOSO diet had a similar effect on liver antioxidant enzyme activities as the OO diet. In conclusion, it appears that changes in the liver fatty acid composition due mainly to n-3 lipids may enhance the efficiency of the antioxidant defence system and may yield a benefit in the hypertension status. The two monounsaturated fatty acids oils studied (OO and HOSO), with the same high content of oleic acid, but different content of natural antioxidants, had similar effects on the antioxidant enzyme activities studied.

Influence of dietary cholesterol on polyunsaturated fatty acid composition, fluidity and membrane-bound enzymes in liver microsomes of rats fed olive and fish oil

Male rats were fed diets containing olive or marine fish oils (10% w/w) with or without added cholesterol (1% w/w). After six weeks of feeding, the major fatty acid composition, fluidity, fatty acid desaturating and cholesterol biosynthesis/esterification related enzymes of liver microsomes were determined. Both olive oil and marine fish oil diets, without added cholesterol, enriched content of oleic and docosahexaenoic acids, respectively, of rat liver microsomes. The results were consistent with reduction in delta 6 and delta 5 desaturation of n-6 essential fatty acids and higher fluidity in the marine origin oil group. Inclusion of cholesterol into diets resulted in decreased membrane arachidonic acid content, with concomitant increase in linoleic acid content. Cholesterol feeding also decreased delta 6 and delta 5 desaturase activities, as well as membrane fluidity. Furthermore, the activity of acyl-CoA:cholesterol acyltransferase decreased, whereas the activity of hydroxymethylglutaryl-CoA reductase increased, in liver microsomes from both cholesterol-fat groups.

Endothelium-dependent vasorelaxation induced by L-carnitine in isolated aorta from normotensive and hypertensive rats.

The aim of this work was to investigate the mechanism of the vasodilatory effect induced by L‐carnitine. Relaxation produced by L‐carnitine was studied in rat aortic rings with and without functional endothelium, pre‐contracted with phenylephrine by adding cumulative doses of L‐carnitine (10−7 to 10−3 M). The relaxation evoked by L‐carnitine reached higher values in aortic rings from spontaneously hypertensive rats than those obtained in arteries from normotensive rats; no relaxation was produced in de‐endothelialized arteries. However, in the presence of NG‐nitro‐L‐arginine (3 × 10−5 M, a nitric oxide synthase inhibitor), Ro 68070 (10−4 M, a thromboxane synthetase inhibitor‐thromboxane A2/prostaglandin H2 receptor antagonist) or ICI 192605 (10−5 M, a thromboxane A2 receptor antagonist) the relaxant response to L‐carnitine was significantly inhibited. These results show that L‐carnitine induced endothelium‐dependent relaxation in the rat aorta and the mechanism of this relaxation appeared to be mostly mediated by endothelial production of nitric oxide but also could involve prevention of the action of cyclooxygenase endothelial products acting on the thromboxane A2/prostaglandin H2 receptor.