Stéphanie Delemasure

Anti-hypertensive effects of Rosuvastatin are associated with decreased inflammation and oxidative stress markers in hypertensive rats.

Among their pleiotropic effects, statins exert antioxidant and anti-inflammatory properties. The aim of this study was to evaluate in normotensive (WKY) and in spontaneously hypertensive rats (SHR) the effect of rosuvastatin (ROSU) treatment on (1) plasma inflammation markers and endogenous NO synthase inhibitor (ADMA) levels, (2) reactive oxygen species (ROS) generated by circulating leukocytes and (3) vascular oxidative stress and tissue inflammation markers. Plasma cytokines were higher in SHR than in WKY, except for IL-4, which was lower in SHR than in WKY. SHR monocytes exhibited higher production of ROS than did WKY monocytes. In the experimental conditions, ROSU did not modify plasma cholesterol levels in SHR but attenuated the increase in systolic blood pressure. In SHR only, ROSU lessened pro-inflammatory cytokines and ADMA levels, increased IL-4 and reduced ROS production in circulating monocytes. These results demonstrate the beneficial effects of ROSU in SHR, independently of any lowering of cholesterol levels.

After four hours of cold ischemia and cardioplegic protocol, the heart can still be rescued with postconditioning.

Background. There is evidence that ischemia lasting more than 4 hours affects cardiac allograft survival. Ischemia and reperfusion are associated with additional deleterious effects. Protective effects of preconditioning are already being used but protocols based on postconditioning have not been evaluated. We tested the impact of postconditioning on hearts maintained in the cold for a long period of total global ischemia and we compared the results with those obtained with pyruvate, a cardioprotective molecule. Methods. Isolated working rat hearts were subjected to a global total ischemia (4 h/4°C), followed by 45 min of reperfusion. Postconditioning consisted of brief total global ischemia applied three times during the onset of reperfusion (ischemia: 30 sec, reperfusion: 30 sec). Superoxide anion production and collagen content were evaluated on cryosections. Results. Our results showed that postconditioning led to improvements in cardiac functions that were comparable to those conferred by pyruvate. Postconditioning reduced myocardial damage, gave better functional recovery, and better preserved the collagen content. It reduced the duration of arrhythmias at the onset of reperfusion. In the postconditioning group, this improvement was associated with a reduction in superoxide production. Conclusions. In conclusion, our study showed that postconditioning induced good cardioprotective effects in a long cold (4 hr/4°C) ischemia protocol and led to lower O2·− production in part mediated by the reduction in NAPDH oxidase activity. It is interesting to note that, in our experimental conditions, the beneficial effects of postconditioning were comparable to those produced by pyruvate.

Postnatal overfeeding in rats leads to moderate overweight and to cardiometabolic and oxidative alterations in adulthood.

In contrast to the masses of data on obesity, few data are available concerning the cardiometabolic and oxidative consequences of moderate overweight. The model of postnatal overfeeding (OF) induces an increase in body weight at weaning that remains during adult life. Litters of Wistar rats were either maintained at 12 pups (normal-fed group, NF), or reduced to 3 pups at birth in order to induce OF. At 6 months of age, metabolic parameters, circulating oxidative stress and aortic and coronary vasoreactivity were assessed. Cardiac susceptibility to ischemia-reperfusion injury was also evaluated ex vivo as were markers of cardiac remodeling. OF led to an increase in body weight at weaning (+50%); the increase in body weight persisted throughout adult life, but was less marked (+10%). Significant increases in plasma levels of fasting glucose, insulin and leptin were found in OF rats. An increase in both plasma hydroperoxides and cardiac superoxide dismutase activity and a decrease in plasma ascorbate were found in OF rats. Vasoreactivity was not modified, but ex vivo, after 30 min of ischemia, isolated hearts from OF rats showed lower recovery of coronary flow along with a greater release of LDH. Studies on heart tissues showed an increase in collagen content and increased expression and activity of MMP-2. Our findings show that moderate overweight in adult rats, induced by postnatal overfeeding, leads to both metabolic and oxidative disturbances as well as a higher susceptibility to cardiac injury after ischemia ex vivo, which may be explained, at least in part, by ventricular remodeling.

Rapeseed Protein in a High-Fat Mixed Meal Alleviates Postprandial Systemic and Vascular Oxidative Stress and Prevents Vascular Endothelial Dysfunction in Healthy Rats

High-saturated fat and high-sucrose meals induce vascular endothelial dysfunction, the early hallmark of atherogenesis. The impact of dietary protein on vascular homeostasis remains misunderstood. In this study, we investigated whether rapeseed protein, an emergent arginine- and cysteine-rich protein, can acutely modulate the onset of adverse effects induced by a high-saturated fat meal (HFM). In a series of crossover experiments, healthy rats received 3 HFM (saturated fat: 60%; sucrose: 20%; protein: 20% energy) with the protein source being either total milk protein (MP; control), rapeseed protein (RP), or MP supplemented with cysteine and arginine to the same level as in RP (MP+AA). Endothelium-related vascular reactivity, measured as an acetylcholine-induced transient decrease in blood pressure, and plasma triglycerides, hydroperoxides, cyclic GMP (cGMP), and free 3-nitrotyrosine were measured before and 2, 4, and 6 h after meals. Superoxide anion production, expressed as ethidine fluorescence, was measured in the aorta 6 h after meals. Whereas plasma triglycerides rose similarly in all meals, the decrease in vascular reactivity after MP was attenuated after MP+AA and entirely prevented after RP. The type of meal had no consistent effect on plasma cGMP and free 3-nitrotyrosine over the postprandial period. The postprandial increase in plasma hydroperoxides differed according to the meal, and concentrations were 43% lower 6 h after MP+AA and RP than after MP. Aortic superoxide anion production was 36% lower 6 h after RP than MP. These results show that substituting rapeseed protein for milk protein markedly reduces vascular and oxidative disturbances induced by an HFM and this may be mediated in part by cysteine and arginine.

Beneficial Effects of Myocardial Postconditioning are Associated With Reduced Oxidative Stress in a Senescent Mouse Model

Background. There is at present a tragic lack of organs available for transplantation. This has led to the harvesting of hearts from older donors. Unfortunately, hearts from such donors are much more sensitive to ischemic insult. Models such as “Senescence Accelerated Mouse” Prone 8 (SAM-P8) can help understand this sensitivity. New cardioprotective techniques such as postconditioning (PostC) could be of interest in this context. We studied (1) senescence in vessels and hearts and (2) the ability of the senescent heart to adapt to an ischemia-reperfusion (I/R) sequence in the context of PostC. Methods. Isolated working mouse hearts (8 months) were subjected to total ischemia, followed by 36 min of reperfusion; PostC was performed in the first minutes of reperfusion as three 10-sec sequences of I/R. Superoxide anion (O2·−) production was evaluated on heart and aorta cryosections with the dihydroethidium staining method. The collagen content in aortas was quantified. Results. The aortas of SAM-P8 mice showed a higher production of O2·− and a higher collagen content than did those of SAM-R1 mice (P<0.05). During reperfusion, SAM-P8 hearts showed the worst recovery of cardiac output. PostC significantly reduced reperfusion dysfunction (P<0.05) and was associated with a reduction in heart O2·− staining. Conclusions. These results indicate that SAM-P8 presents a high degree of cardiovascular oxidative stress and a higher susceptibility to I/R injury, which confirms the senescence of the cardiovascular system in these animals. However, they remain sensitive to cardioprotection afforded by in vitro PostC.

Effects of angiotensin-1 converting enzyme inhibition on oxidative stress and bradykinin receptor expression during doxorubicin-induced cardiomyopathy in rats.

To evaluate the mechanisms and the impact of the angiotensin-converting enzyme inhibitor perindopril (P) in a model of doxorubicin (D)-induced cardiotoxicity, male Wistar rats received D (1 mg/kg/d, IP for 10 days), P (2 mg/kg/d by gavage from day 1 to day 18), D (for 10 days) + P (for 18 days) or saline. D decreased systolic blood pressure and body and heart weights. Left ventricular diastolic diameter was increased by D (P < 0.01), but it was not attenuated by P. D decreased plasma vitamin C (P < 0.05) and increased the ascorbyl radical/vitamin C ratio (P < 0.01). This ratio was attenuated by P. No difference was found among groups in cardiac troponin I, brain natriuretic peptide concentrations, and tissue oxidative stress (OS). Myocardial MCP-1 expression was higher in the D group. Cardiac kinin receptor (B1R and B2R) expression was not affected by D, yet binding sites for B2R and B1R were increased in D+P and P groups, respectively (P < 0.05). In conclusion, D induced cardiac functional alterations, inflammation and plasma OS whereas tissue OS, and cardiac kinin receptors expression were not modified. P did not improve cardiac performance, but it modulated kinin receptor expression and enhanced antioxidant defense.

General oxidative stress during doxorubicin-induced cardiotoxicity in rats: Absence of cardioprotection and low antioxidant efficiency of alpha-lipoic acid

To evaluate the effects of alpha-lipoic acid (AL) in a model of doxorubicin (DOX)-induced cardiotoxicity, male Wistar rats were treated with DOX (1 mg/kg/d; 10 d) in combination or not with AL (50 mg/kg/d; 15 d). Plasma oxidative stress was determined by hydroperoxides (ROOH) and the ascorbyl radical/ascorbate ratio. One and two months later, the functional parameters of the hearts were determined in vivo by catheterization and cardiac oxidative stress was assessed by malonedialdehyde (MDA) and O₂*⁻ (dihydroethidium fluorescence) content in tissue. After two months, body weight was higher in the DOX-AL group than in DOX (+16%), but this was due to ascites. Histological liver alterations were observed in both the DOX and DOX-AL groups. Plasma ROOH concentrations decreased after 10 days of AL treatment, but were greater in both the DOX and DOX-AL groups. After two months, a decrease in the cardiac contractility index (-27% and -29%, respectively) and cardiac hypertrophy were observed in DOX and DOX-AL. These dysfunctions were associated with 1) a reduction in plasma ascorbate levels and an increase in the ascorbyl/ascorbate ratio and 2) an increase MDA and O₂*⁻ content in cardiac tissue. In conclusion, a cumulative dose of 10 mg/kg doxorubicin induced functional alterations in the heart associated with plasma and cardiac oxidative stress. The co-administration of the antioxidant compound AL had no beneficial effects in this situation.

Whole-body basal nitric oxide production is impaired in postprandial endothelial dysfunction in healthy rats.

In healthy humans, a high-saturated-fat/high-sucrose meal induces vascular endothelial dysfunction, a hallmark of atherogenesis. This transient dysfunction indicates a loss in nitric oxide (NO) production and/or bioactivity in the vasculature but it remains unknown if this is the local manifestation of a general impairment in NO pathway in the postprandial state. Here, we studied whole-body NO production and systemic NO bioactivity in postprandial endothelial dysfunction, as induced by a high-saturated-fat, high-sucrose meal. We first developed a physiological test of endothelial function on conscious rats, based on the transient fall in blood pressure after iv acetylcholine, and showed that this response was NO-dependent. As assessed with this method in healthy rats, endothelial function decreased during the postprandial state, being 60+/-7% lower than baseline at 6h after the meal challenge, associated with important elevations in plasma triglycerides and hydroperoxides. Aortic superoxide anion production, as assessed by oxidative fluorescent detection, was higher 6h after the meal challenge than after the nutrients vehicle (water). During the postprandial period, plasma cGMP, but not plasma ANP, markedly decreased, indicating a general decrease in NO bioavailability, which was numerically maximal 4h after the meal challenge. As determined 4h after ingestion by a tracer-based method using iv [(15)N(2)-(guanido)]-arginine, the whole-body NO production fell by 27+/-9% postprandially. This is the first study evidencing that a meal challenge that impairs the stimulated, NO-mediated, vascular response also reduces whole-body basal NO production and bioavailability. Postprandial pathophysiology may build on this general, fundamental alteration in NO production.

A peroxynitrite decomposition catalyst: FeTPPS confers cardioprotection during reperfusion after cardioplegic arrest in a working isolated rat heart model

Heart transplant is considered to be an extremely severe ischemia–reperfusion sequence. Post‐ischemic dysfunction triggers multiple processes especially oxidative stress, but the mechanisms remain unclear. Free radical interactions lead to peroxynitrite generation, which seems to be involved in early post‐transplant heart failure. The aim of this study was to evaluate the potential impact of a peroxynitrite decomposition catalyst: FeTPPS (5,10,15,20‐tetrakis‐[4‐sulfonatophenyl]‐porphyrinato‐fer[III]) and pyruvate on myocardial functional recovery after cardioplegic arrest using an experimental protocol in rat hearts. Isolated working rat hearts were subjected to ischemia (4 h at 4 °C in cardioplegic solutions), followed by 45 min of reperfusion. Four groups were constituted: control, pyruvate: (2 mm) added to cardioplegic and Ringer–lactate solutions, FeTPPS: (10 μm) perfused during the reperfusion, and a combination of both treatments. Lactate dehydrogenase (LDH) activity was assessed during the reperfusion to evaluate the level of cardiac injury. Oxidative stress was evaluated on heart slices using a fluorescent probe: dihydroethidium, and the collagen content was assessed using picro‐Sirius coloration. Global post‐ischemic recovery in the control group was about 35% of pre‐ischemic values. Results showed that addition of pyruvate led to an increase in myocardial function and to a decrease in LDH activity released during the reperfusion. FeTPPS protected against injury after cardioplegic arrest during reperfusion. No additive effect of the two treatments (pyruvate + FeTPPS) was observed. The collagen content was better preserved in the FeTPPS group than in the control and pyruvate groups. In conclusion, this study shows that peroxynitrite plays an important role in the functional and cellular alterations associated with cardiac ischemia–reperfusion sequences and confirms that pyruvate helped to preserve myocardial function. The use of the peroxynitrite decomposition catalyst (FeTPPS) may help to improve myocardial preservation during a prolonged ischemia sequence.

Un dithiol endogène aux propriétés antioxydantes : l’acide alpha-lipoïque, utilisation potentielle dans les pathologies cardiovasculaires

Alpha-Lipoic acid (ALA) is a natural compound, chemically named 1,2-dithiolane-3-pentanoic acid, also referred to as thioctic acid. In humans, ALA is synthetized by the liver and other tissues with high metabolic activity: heart, kidney. ALA is both water and fat soluble and therefore, is widely distributed in both cellular membranes and cytosol. Recently, a greater deal of attention has been given to antioxidant function for ALA and its reduced formed: dihydrolipoic acid (DHLA). ALA scavenges hydroxyl radicals, hypochlorous acid and singlet oxygen. It may also exert antioxidant effects in biological systems through transitional metal chelation. Dihydrolipoic acid has been shown to have antioxidant but also pro-oxidant properties in systems in which hydroxyl radical was generated. ALA/DHLA ratio has the capacity to recycle endogenous antioxidants such as vitamin E. A number of experimental as well as clinical studies point to the usefulness of ALA as a therapeutic agent for such diverse conditions as diabetes, atherosclerosis, insulin resistance, neuropathy, neurodegenerative diseases and ischemia-reperfusion injury. ALA represents a potential agent on the vascular endothelium, recording to ALA/DHLA redox couple is one of the most powerful biological antioxidant systems.