Françoise Goirand

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.

Time course of asymmetric dimethylarginine (ADMA) and oxidative stress in fructose-hypertensive rats: A model related to metabolic syndrome

OBJECTIVE Asymmetric dimethylarginine (ADMA) is an endogenous modulator of endothelial function and oxidative stress, and increased levels of this molecule have been reported in some metabolic disorders and cardiovascular diseases. The aim of this work was to analyze the time course of dimethylarginine compounds and oxidative stress levels and the relationship between these and cardiovascular function in fructose-hypertensive rats. METHODS AND RESULTS 90 male Sprague-Dawley rats were randomized into 2 groups, fed for 3 months with standard (C) chow supplemented or not with fructose (F, 60%). After sacrifice at different weeks (W), the aorta and plasma were harvested to assess the vascular and biochemical parameters. Our work showed that the plasma levels of ADMA in the fructose-fed rats increased after 2 weeks of the diet (1.6 ± 0.3 μM vs. 1.2 ± 0.3 μM, p < 0.05) with no changes in plasma levels of either SDMA or L-arginine and after an increase in glycemia. Levels of vascular oxidative stress, estimated in aortic segments using an oxidative fluorescence technique, were higher in the F group (W2: 1.14 ± 0.2% vs. 0.33 ± 0.02%, p < 0.01). An increase in expression levels of nitrotyrosine (3-fold) and iNOS (2-fold) were noted in the fructose-fed rats. After 1 month, this was associated with a significant increase in NAD(P)H oxidase activity. Concerning vascular function, a 15% decrease in maximal endothelium-dependent relaxation was found in the aorta of the F group. Our work showed that the presence of exogenous L-MMA, an inhibitor of NO synthase, was associated with a significant reduction in endothelium-dependent relaxation in isolated aorta rings of the C group; this effect was not observed in the vessels of fructose-fed rats. CONCLUSION Our findings suggest that the elevated levels of ADMA observed could in part be secondary to the early development of oxidative stress associated with the development of hypertension.

Role of potassium channels and nitric oxide in the relaxant effects elicited by β‐adrenoceptor agonists on hypoxic vasoconstriction in the isolated perfused lung of the rat

The aims of this study were to compare, in the rat isolated perfused lung preparation, the antagonist effects of a nonselective β‐adrenoceptor agonist (isoprenaline), a selective β2‐adrenoceptor agonist (salbutamol) and a selective β3‐adrenoceptor agonist (SR 59104A) on the hypoxic pulmonary pressure response, and to investigate the role of K+ channels, endothelium derived relaxing factor and prostaglandins in these effects. K+ channels were inhibited by glibenclamide, charybdotoxin or apamin, NO synthase and cyclo‐oxygenase were inhibited by NG‐nitro‐L‐arginine methyl ester (L‐NAME) and indomethacin, respectively. Hypoxic ventilation produced a significant increase in perfusion pressure (+65%, P<0.001) and L‐NAME significantly increased this response further (+123%, P<0.01). After apamin, L‐NAME, indomethacin, post‐hypoxic basal pressure did not return to baseline values (P<0.001). Glibenclamide partially inhibited the relaxant effects of isoprenaline (P<0.05) and salbutamol (P<0.001) but not that of SR 59104A. In contrast, charybdotoxin and apamin partially inhibited the relaxant effects of SR 59104A (P=0.053 and <0.01, respectively) but did not modify the effects of isoprenaline and salbutamol. L‐NAME partially inhibited the dilator response of salbutamol (P<0.01) and SR 59104A (P<0.05) but not that of isoprenaline. We conclude that (a) EDRF exerts a significant inhibition of the hypoxic pulmonary response, (b) SKCa channel activation, EDRF and prostaglandins contribute to the reversal of the hypoxic pressure response, (c) the vasodilation induced by isoprenaline is mediated in part by activation of KATP channels, that of salbutamol by activation of KATP channels and EDRF. In contrast, SR 59104A partly operates through BKCa, SKCa channels and EDRF activation, differing in this from the β1 and β2‐adrenoceptor agonists.

Stimulation of the ADRB3 Adrenergic Receptor Induces Relaxation of Human Placental Arteries: Influence of Preeclampsia

Abstract Preeclampsia, which complicates 3–8% of pregnancies, is one of the leading causes of neonatal morbidity and mortality. Its pathophysiology remains unclear. The aim of the present study was to investigate the presence and the role of β2- and β3-adrenergic receptors (ADRB2 and ADRB3, respectively) in human placental arteries and to assess the influence of preeclampsia on ADRB responsiveness. SR 59119A, salbutamol, and isoproterenol (ADRB3, ADRB2, and nonselective ADRB agonists, respectively) induced a concentration-dependent relaxation of placental artery rings obtained from women with uncomplicated or preeclamptic pregnancies. SR 59119A-induced relaxation was unaffected by the blockade of ADRB1 and ADRB2 by 0.1 μM propranolol but was significantly decreased by the blockade of ADRB1, ADRB2, and ADRB3 by 10 μM propranolol. Both SR 59119A and salbutamol were associated with a significant increase in cAMP production that was significantly inhibited by pretreatment with 0.1 μM propranolol only for salbutamol. SR 59119A-induced relaxation (Emax = 28% ± 5% vs. 45% ± 4%, respectively) and cAMP production (2.7 ± 0.5 vs. 4.9 ± 0.4 pmol/mg of protein, respectively; P < 0.01) were decreased in arteries obtained from preeclamptic compared to normotensive women. Both ADRB2 and ADRB3 transcripts were expressed at the same level between arteries from normotensive and preeclamptic women. Western blot analysis, however, revealed a decreased expression of the ADRB3 immunoreactive protein in arteries from preeclamptic compared to normotensive women. We suggest the presence of functional ADRB2 and ADRB3 in human placental arteries. Even if preeclampsia is associated with an impairment of the ADRB3 responsiveness, ADRB3 agonists may have future pharmaceutical implications in the management of pregnancy-related disorders.

hypoxic Vasoconstriction of Rat Main Pulmonary Artery: Role of Endogenous Nitric Oxide, Potassium Channels, and Phosphodiesterase Inhibition

Summary: This study investigated the influence of NO, potassium (K+) channel blockade, and the phosphodiesterase inhibitors (PDEIs) theophylline (nonselective PDEI), siguazodan (PDE3I), rolipram (PDE4I), and zaprinast (PDE5I) on rat isolated main pulmonary artery hypoxic (95% N2 and 5% CO2) vasoconstriction. Hypoxic vasoconstriction increased by 27% (p < 0.01) in the presence of the NO synthase inhibitor l‐NAME (10−4 M), and by 15% (p < 0.05) in the presence of the KATP channel blocker glibenclamide (10−6 M), without potentiation by the combination of these two drugs. Hypoxic vasoconstriction decreased by 28% (p < 0.01) in presence of the Kv,‐voltage‐dependent channel blocker 4‐aminopyridine (10−3 M), whereas the other K+ channel blockers, charybdotoxin (BKCa, large‐conductance Ca2+‐sensitive K+ channels) and apamin (SKCa, small‐conductance Ca2+‐sensitive K+ channels) had no effect. The nonselective PDEI theophylline induced a concentration‐dependent relaxation (pD2 = 4.05, Emax = 90% [expressed as a percentage of maximal relaxation induced by papaverine 10−4 M]). Among the selective PDEIs, siguazodan was significantly (p < 0.01) more efficient than rolipram and zaprinast (Emax values were 84%, 67%, and 58%, respectively) and significantly (p < 0.05) more potent than zaprinast (pD2 values were 6.48, 6.34, and 6.16 for siguazodan, rolipram, and zaprinast). Glibenclamide and l‐NAME significantly (p < 0.05) shifted the concentration‐response curve (CRC) for zaprinast to the right, and l‐NAME shifted the CRC significantly to the right for siguazodan. In the presence of l‐NAME, glibenclamide had no effect on the CRC of zaprinast. We conclude that (a) NO exerts a permanent inhibitory effect against hypoxic vasoconstriction that might be mediated in part by an activation of KATP channels; (b) a 4‐aminopyridine‐sensitive K+ channel is involved in vasoconstriction under hypoxic conditions; (c) PDEs 3 and 5 are the predominant PDE isoforms in rat pulmonary artery relaxation; and (d) NO and KATP, but neither BKCa, SKCa, nor Kv channels, are involved in the relaxant effect of PDEIs.

ADRB3 Adrenergic Receptor Is a Key Regulator of Human Myometrial Apoptosis and Inflammation During Chorioamnionitis

Abstract The pathophysiology underlying preterm labor triggered by inflammatory conditions such as chorioamnionitis remains largely unclear. It has already been suggested that beta-3 adrenergic (ADRB3) agonists might be of interest in the pharmacological management of preterm labor. Although there is evidence implicating ADRB receptors in the control of inflammation, there are minimal data relating specifically to ADRB3. To explore the cellular consequences of chorioamnionitis and detect apoptosis, we first performed immunostaining and Western blot experiments on human myometrial samples obtained from women with confirmed chorioamnionitis. We then developed an in vitro model of chorioamnionitis by incubating the myometrial samples obtained from uncomplicated pregnancies with Escherichia coli lipopolysaccharide (LPS). We observed that chorioamnionitis was associated with a significant increase in cleaved CASP3 protein expression, as well as chromatin condensation, which were reproduced experimentally by LPS stimulation (10 μg/ml, 48 h). Lipopolysaccharide stimulation of normal human myometrium also induced CASP3 transcripts, increased the proapoptotic marker BAX, and decreased the antiapoptotic marker BCL2. Lipopolysaccharide-induced apoptosis was antagonized by neutralization of secreted tumor necrosis factor by a specific antibody. Furthermore, LPS stimulation increased medium culture levels of proinflammatory cytokines interleukin 6 (IL6) and IL8. Lipopolysaccharide-induced apoptosis and cytokine production were prevented by the new and potent ADRB3 agonist SAR150640 in a concentration-dependent manner. SAR150640 by itself did not exhibit any effect on apoptosis or cytokine production in control tissues. This study shows that chorioamnionitis is associated with apoptosis of human myometrial cells. It emphasizes the potential therapeutic interest of ADRB3 agonists in the field of preterm labor and other inflammatory conditions.

ETA, mixed ETA/ETB receptor antagonists, and protein kinase C inhibitor prevent acute hypoxic pulmonary vasoconstriction: influence of potassium channels.

The aims of this study were to investigate the effects of a selective ETA (BQ-123), a selective ETB (BQ-788), and a specific mixed ETA/ETB receptor antagonist (bosentan) on the pulmonary vasoconstriction induced by hypoxia in the isolated perfused rat lung, and the role of nitric oxide, adenosine triphosphate–sensitive (KATP), large conductance Ca+-activated (BKCa) and 4-aminopyridine–sensitive voltage-gated K+ channels (KV) in the relaxant effects of the selective ETA receptor antagonist BQ-123 and a protein kinase C inhibitor, bisindolylmaleimide I. K+ channels were inhibited by glibenclamide, charybdotoxin, and 4-aminopyridine and nitric oxide synthase by l-NG-nitroarginine methyl ester (l-NAME). Hypoxic ventilation produced a significant pressure response (+57%, p < 0.001). BQ-123, bosentan, and bisindolylmaleimide I induced a concentration-dependent decrease of the hypoxic pressure response (p < 0.001), whereas BQ-788 did not exhibit any inhibitory effect against hypoxic pressure response. Glibenclamide, charybdotoxin, and 4-aminopyridine partially opposed the inhibitory effects elicited by BQ-123 (p < 0.05), but l-NAME did not modify these effects. The effects of bisindolylmaleimide I on hypoxic pressure response were unaffected by glibenclamide, charybdotoxin, or 4-aminopyridine. The authors conclude that (a) ETA receptors and protein kinase C are involved in the modulation of hypoxic pulmonary vasoconstriction; and (b) the ETA antagonist BQ-123 opposes hypoxic pulmonary vasoconstriction through KATP, Kv, and BKCa channels, differing in this from the protein kinase C inhibitor bisindolylmaleimide I. These results suggest that BQ-123 operates through a mechanism independent of bisindolylmaleimide I–inhibited protein kinase C isoforms.

SAR150640, a selective β3-adrenoceptor agonist, prevents human myometrial remodelling and activation of matrix metalloproteinase in an in vitro model of chorioamnionitis

Background and purpose:  The uterine pathophysiology underlying inflammatory conditions such as chorioamnionitis remains largely unclear. As we have shown that β3‐adrenoceptors act as regulators of myometrial inflammation, we wanted to investigate the potential role of β3‐adrenoceptors in preventing uterine remodelling induced by inflammation.

Relaxant effects of selective phosphodiesterase inhibitors on U46619 precontracted human intralobar pulmonary arteries and role of potassium channels.

We examined the influence of K+ channel antagonists on the vasorelaxation induced by theophylline (non selective PDEI), siguazodan (PDE3I), rolipram (PDE4I) and zaprinast (PDE5I) in human intralobar pulmonary arteries. All PDEI tested induced a concentration-dependent relaxation with theophylline being significantly (p < 0.05) more efficient and rolipram more potent than PDE5I and PDE3I (Emax values, expressed as a percentage of maximal relaxation by papaverine 10−4M, were 92% ± 2%, 84% ± 8%, 90% ± 4% and 99% ± 1%, and pD2 values were 7.30 ± 0.35, 6.14 ± 0.25, 5.86 ± 0.17, and 4.85 ± 0.47 for rolipram, siguazodan, zaprinast and theophylline, respectively). 4-Aminopyridine (4-AP, Kv, voltage dependent channel blocker, 1 m M) induced a significant increase (+17% p < 0.05) of U46619-induced vasoconstriction whereas the other K+-channels blockers, glibenclamide (KATP channels, 1 &mgr;M) charybdotoxin (predominant BKCa, large conductance Ca2+-sensitive K+ channels, 0.1 &mgr;M) and apamine (SKCa, small conductance, 0.3 &mgr;M) were without effect. The concentration response curves (CRC) for rolipram were significantly shifted to the right by glibenclamide (1 &mgr;M), charybdotoxin (0.1 &mgr;M) and 4-AP (1 m M). The CRC for siguazodan was significantly displaced to the right by 4-AP. None of the potassium channel blockers displaced the CRC for zaprinast and theophylline. Apamine was without effect on the CRC for all the PDEI used in this study. (1) PDE3, 4 and 5 are functionally present in human intralobar pulmonary arteries; (2) the vasoconstriction induced by U46619 is downregulated by 4-aminopyridine sensitive-K+ channels; (3) the relaxant effects of rolipram (PDE4I) are partly mediated through KATP, BKCa, and Kv potassium channels and those of siguazodan (PDE3I) by Kv potassium channels.

Dexlansoprazole Delayed Release: Pharmacotherapy of Erosive Esophagitis and GERD

Dexlansoprazole MR is a modified release formulation of the R-enantiomer of lansoprazole, which employs a novel Dual Delayed Release (DDR) technology. Pharmacokinetic studies have shown that the DDR technology provides a two peaks drug release, accuring 1–2 hours and 4–5 hours after dosing, leading to an extended duration of therapeutic plasma drug concentrations compared with conventional delayed release lansoprazole. Dexlansoprazole MR 30 and 60 mg provided superior intragastric pH control compared to that obtained with lansoprazole 15 mg and 30 mg once daily dosing. Dexlansoprazole can be taken without regard to food. The drug has been shown to be as efficacious as lansoprazole in healing, and superior to placebo in maintaining healing, of erosive esophagitis. Dexlansoprazole appears to be well tolerated with a comparable safety profile to lansoprazole. Overall, dexlansoprazole DR has an interesting pharmacokinetic profile and is effective and well tolerated in the healing and maintenance of erosive esophagitis and in the treatment of GERD. Nevertheless in the absence of head-to-head comparison there is no mean to recommend its use preferentially to other PPIs.