Pere Puig-Parellada

A flavonoid-rich diet increases nitric oxide production in rat aorta.

Red wine intake is associated with a low risk of cardiovascular disease. This effect has been partly attributed to the action of polyphenolic compounds, which decrease the oxidation of plasma low density lipoproteins. Moreover, nitric oxide (•NO) is a vasodilator and polyphenolic compounds induce endothelium‐dependent vasorelaxation in vitro. Here we studied whether a diet rich in dealcoholated red wine (DRW) increases acetylcholine‐induced vasorelaxation and whether ingestion of DRW‐, quercetin‐ or catechin‐rich diets modifies the •NO‐cyclic guanosine‐3′,5′‐monophosphate (cyclic GMP) pathway and superoxide anion (O2.−) release in aorta in a resting state in rats fed semi‐purified diets containing either 35% (v w−1) DRW, 0.3% (w w−1) quercetin or 0.3% (w w−1) catechin for 10 days. •NO‐mediated vasorelaxation induced by acetylcholine was greater in rats fed the DRW‐rich diet than in those that received the control diet. Expression of endothelial •NO synthase (eNOS) was similar in the four dietary groups. The aortic rings of rats fed either the DRW‐, quercetin‐, or catechin‐rich diets showed higher NOS activity, •NO production and cyclic GMP content than those of rats fed the control diet. No changes were observed in O2.− production. In summary, diets rich in either DRW, quercetin or catechin induced endothelium‐dependent vasorelaxation in rat aorta in a resting state through the enhancement of •NO production, without modifying O2.− generation, thus the bioavailability of •NO was increased. The increase in the •NO‐cyclic GMP pathway explains the beneficial effect of flavonoids at vascular level.

Loss of adaptation to oxidative stress as a mechanism for aortic damage in aging rats

Cells are armed with a vast repertoire of antioxidant defence mechanisms to prevent the accumulation of oxidative damage. The cellular adaptive response is an important antioxidant mechanism against physiological and pathophysiological oxidative alterations in a cell’s microenvironment. The aim of this paper was to study, in the rat aorta, whether this adaptive response and the inflammation associated with oxidative stress were expressed throughout the aging process. We examined the rat aorta, as it is a very sensitive tissue to oxidative stress. Male Wistar rats of 1.5, 3, 12, 18 and 24 months of age were used. Superoxide anion (O2−) generation; levels of two antioxidant enzymes, superoxide dismutase (SOD) and catalase; and the levels of prostaglandin E2 (PGE2), an inflammatory marker, were measured. The results for rats at different ages were compared with those for 3 months of age. A balance between production of O2− and SOD activity was found in the aorta of rats from 1.5 to 12 months old. Oxidative stress was present in the aorta of old animals (18–24) months), due to a failure in the mechanisms of adaptation to oxidative stress. The observed increase in PGE2 levels in these rats reflected an inflammatory response. All together suggest that vascular oxidative stress and the inflammatory process observed in the old groups of rats could be closely related to vascular aging. Our results also remark the importance of the adaptative response to oxidative stressResumenLas células están equipadas con una amplia gama de mecanismos de defensa antioxidante para prevenir la acumulación de lesiones oxidativas. La respuesta celular de adaptación constituye un importante mecanismo antioxidante para prevenir las alteraciones en el microentorno celular tanto a nivel fisiológico como patofisiológico. El propósito de este trabajo fue estudiar en aorta de rata si la respuesta de adaptación así como la inflamación, asociadas ambas con el estrés oxidativo, se expresan a lo largo del proceso de envejecimiento. Se ha empleado aorta de rata ya que constituye un tejido muy sensible al estrés oxidativo. Se utilizaron ratas macho Wistar de 1,5,3,12,18 y 24 meses de edad y se estudiaron la producción de anion superoxido (O2−), los niveles de dos enzimas antioxidantes, superoxido dismutasa (SOD) y catalasa, así como los niveles de prostaglandina E2 (PGE2), un indicador de la inflamación. Los resultados obtenidos a las diferentes edades se compararon con los obtenidos con las ratas de 3 meses de edad. Nuestros resultados demostraron un equilibrio entre producción de O2− y actividad de SOD en las ratas de entre 1,5 y 12 meses de edad. En la aorta de los animales viejos (18–24 meses) se detectó mayor estrés oxidativo debido a un fallo en los mecanismos de adaptación al mismo, mientras que el aumento observado en los niveles de PGE2 en estos animales refleja una respuesta inflamatoria. En conjunto, nuestros resultados sugieren que tanto el estrés oxidativo vascular, como el proceso inflamatorio observados en los grupos de ratas viejas podrían estar fuertemente relacionados con el envejecimiento vascular. Nuestros resultados remarcan también la importancia de la respuesta de adaptación al estrés oxidativo.

Antioxidant defenses and its modulation by iron in carrageenan-induced inflammation in rats

The concentration of endogenous antioxidants has been studied in rats with a carrageenan-induced granuloma. This animal model of inflammation allowed us to study the antioxidant defenses and the oxidative stress in plasma and in the site of inflammation (exudate) and their modulation by the levels of iron in the organism after iron-dextran or desferrioxamine administration. In inflamed rats without supplementary treatment, an interrelation between urate, ascorbate and vitamin E levels has been observed and it appears to be an important mechanism to prevent the depletion of the antioxidants. Further, the sulphydryl groups, caeruloplasmin and retinol also contribute to the defense in this experimental model. Iron overload increases the production of malondialdehyde and decreases some antioxidants such as ascorbic acid and SH groups but, on the other hand, it raises the levels of urate and caeruloplasmin. However, the protective effect of desferrioxamine has not been observed, and in our conditions this may be due to the induced mobilization of iron. Our results show that antioxidants have an important role in the prevention of lipid peroxidation by free radicals produced during inflammatory processes. This protective effect depends on the stage of inflammation.

Oxidative stress markers in the neocortex of drug-resistant epilepsy patients submitted to epilepsy surgery

PURPOSE While there is solid experimental evidence of brain oxidative stress in animal models of epilepsy, it has not been thoroughly verified in epileptic human brain. Our purpose was to determine and to compare oxidative stress markers in the neocortex of epileptic and non-epileptic humans, with the final objective of confirming oxidative stress phenomena in human epileptic brain. METHODS Neocortical samples from drug-resistant epilepsy patients submitted to epilepsy surgery (n=20) and from control, non-epileptic cortex samples (n=11) obtained from brain bank donors without neurological disease, were studied for oxidative stress markers: levels of reactive oxygen species (ROS), such as superoxide anion (O2(-)); activity of antioxidant enzymes: superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione reductase (GR); and markers of damage to biomolecules (lipid peroxidation and DNA oxidation). RESULTS Compared with non-epileptic controls, the neocortex of epileptic patients displayed increased levels of superoxide anion (P≤0.001), catalase (P≤0.01), and DNA oxidation (P≤0.001); a decrease in GPx (P≤0.05), and no differences in SOD, GR and lipid peroxidation. CONCLUSIONS Our findings in humans are in agreement with those found in animal models, supporting oxidative stress as a relevant mechanism also in human epilepsy. The concurrent increase in catalase and decrease in GPx, together with unchanged SOD levels, suggests catalase as the main antioxidant enzyme in human epileptic neocortex. The substantial increase in the levels of O2(-) and 8-oxo-dG in epileptic patients supports a connection between chronic seizures and ROS-mediated neural damage.

Oxidative stress, nitric oxide and prostaglandin E2 levels in the gastrointestinal tract of aging rats

Objectives To evaluate the presence of oxidative stress and alterations in the levels of two cytoprotective agents, prostaglandin E2 and nitric oxide, in the gastrointestinal tract of aging rats.

Modulation of exudate inflammation parameters in rat carrageenan-induced granuloma by modification of exudate iron levels

We have used the carrageenan-induced pouch-granuloma in rats to investigate how changes in low-molecular-mass iron chelate levels in the exudate, induced by iron loading (iron-dextran) or chelation (desferrioxamine) influence cellular and systemic inflammatory parameters.In the iron-treated group we observed a rapid decrease in the number of leukocytes and exudate volume; there was also an increase in ferritin iron and low-molecular-mass iron chelates, and on the eighth day a systemic response. In the desferrioxamine-treated group we detected a decrease in low-molecular-mass iron chelates, ferritin iron, and an increase in the number of leukocytes. We describe the protective effects of desferrioxamine against the deleterious effects of ferrous iron and relate this to its chelating and scavenging activity.The results suggest that the levels of low-molecular-mass iron chelates modulate the inflammatory response, possibly through their contribution to the oxygen free radical generation, which is responsible for the cell membrane damage and subsequently its death. The modulatory action of iron-dextran and desferrioxamine support our hypothesis.

Carrageenan-induced granuloma and iron status in rats with dietary polyunsaturated fatty acid deficiency

Sprague-Dawley rats were fed for 4 months on a control diet or a polyunsaturated-fatty-acid (PUFA)-deficient diet. The combined effects of iron overload (Fe dextran) or Fe deficiency (desferrioxamine) on carrageenan-induced granuloma were studied. PUFA deficiency induced changes in Fe metabolism, but no alterations in lipid peroxidation variables were observed. Inflammation implied an increase in lipid peroxidation, Fe storage and caeruloplasmin concentration, together with symptoms of anaemia. PUFA deficiency in inflamed rats gave rise to a lower inflammatory response (granuloma weight and prostaglandin E2 concentration) and ethane exhalation. Fe overload potentiated inflammatory and lipid peroxidation processes, whereas Fe deficiency decreased them.

Eicosanoid levels in the neocortex of drug-resistant epileptic patients submitted to epilepsy surgery

There is an increasing body of evidence implicating eicosanoids (arachidonic acid metabolites) in the experimental generation of epileptic seizures and the development of epilepsy. Our purpose was to measure the synthesis of eicosanoids from the cyclooxygenase and lipoxygenase pathways in human brain neocortex tissue samples obtained from epileptic patients, and to compare them with non-epileptic control subjects. Epileptic neocortex specimens demonstrated a significant increase (P<0.001) in the levels of three eicosanoids derived from the cyclooxygenase pathway: Prostaglandin E(2) (PGE(2)), Thromboxane A(2) (TXA(2)), and Prostacyclin (PGI(2)), compared to controls. In the epileptic samples the level of TXA(2) was twice as much the levels of PGI(2), while in the control samples the levels of PGI(2) were slightly higher than TXA(2). Conversely, there were no detectable levels of eicosanoids derived from the lipoxygenase pathway: Leukotriene B(4) (LTB(4)) and Leukotriene C(4) (LTC(4)). The lack of leukotrienes synthesis illustrates that COX pathway is dominant in neocortex of epileptic patients. Our human data are consistent with the results obtained in experimental animal models of epilepsy. The important increase in PGE(2) and TXA(2) suggests that selective inhibition of prostanoid synthesis or blockage of prostanoid receptors might provide novel antiepileptic strategies in human epilepsy.

Role of Iron in Carrageenan-Induced Granuloma: Action of Desferrioxamine and Indometacin

Iron has been implicated in the inflammatory process. In this paper we studied the modulating inflammatory activity of iron in the carrageenan-induced granuloma pouch, taking indometacin as a standard anti-inflammatory drug. Sprague-Dawley rats were injected subcutaneously with desferrioxamine (100 mg/kg) and indometacin (5 mg/kg) for 3 consecutive days before granuloma induction, followed by a daily administration in the granuloma pouch until the day before death. We determined the granuloma weight and assayed in the exudate: volume, number of leukocytes, PGE2 levels and loosely bound iron content at 1 (acute inflammation) and 6 days (chronic inflammation) after granuloma induction. Our results show a dual effect of desferrioxamine, inflammatory in the acute phase and anti-inflammatory in the chronic phase. These results are discussed in relation to chemotaxis and to the potential role of iron on oxygen free radical production, collagen synthesis and hydroperoxide generation, while indometacin acts through the cyclooxygenase pathway.

Influence of aging on thromboxane A2 and prostacyclin levels in rat hippocampal brain slices

We have investigated the influence of age (3, 18, 24 months) on Thromboxane A2 (TXA2) and Prostacyclin (PGI2) levels in hippocampal slices from F344/NHSD rats. A significant increase in TXA2 and PGI2 levels was observed in 18 and 24 months old compared to 3 months old animals. A significant reduction in the ratio TXA2/PGI2 produced by a higher increase in PGI2 was observed in 24 month old animals. The reduction in the TXA2/PGI2 ratio has been related to vasodilatory and antiaggregating effects that may contribute to protect the brain against neuronal damage.