Cellules stromales prostatiques en culture (étude des composantes statique et dynamique de l'hyperplasie bénigne de la prostate )

L'Hyperplasie Bénigne de la Prostate se caractérise par deux composantes, dynamique et statique, entraînant des symptômes obstructifs.La composante dynamique est due à la contraction des cellules musculaires lisses, gouvernée par le récepteur alpha1A-adrénergique (A1A-AR). Afin d'étudier leurs modalités de contraction, nous avons mis au point un nouveau modèle de cellules stromales prostatiques de lapin en culture. Ces cellules, maintenues en différenciation, conservent l'expression des protéines du cytosquelette contractile et du A1A-AR. Ce dernier conserve son couplage avec la voie des MAPK et avec celle du calcium.La composante statique est due à une prolifération cellulaire non tumorale entraînant une augmentation de volume de la glande. Sur un modèle de cellules stromales humaines en culture, nous avons montré que l'extrait de plante Pygeum africanum inhibe la prolifération cellulaire induite par du sérum de veau fœtal, du bFGF et de l'EGF, et ce sans effet de cytotoxicité aiguë.MONTPELLIER-BU Pharmacie (341722105) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

MAP Kinase cross talks in oxidative stress-induced impairment of insulin secretion. Involvement in the protective activity of quercetin

International audienceInsulin secretion preservation is a major issue for the prevention or treatment of type 2 diabetes. We previously showed on β-cells that quercetin (Q), but not resveratrol (R) or N-acetyl cysteine (NAC), amplified glucose-induced insulin secretion in a calcium- and ERK1/2-dependent manner. Quercetin, but not resveratrol or NAC, also protected β-cell function and hyperamplified ERK1/2 phosphorylation in oxidative stress conditions. As quercetin may interfere with other stress-activated protein kinases (JNK and p38 MAPK), we further explored MAPK cross talks and their relationships with the mechanism of the protective effect of quercetin against oxidative stress. In INS-1 insulin-secreting β-cells, using pharmacological inhibitors of MAPK pathways, we found that under oxidative stress (50 μm H2O2) and glucose-stimulating insulin secretion conditions: (i) p38 MAPK phosphorylation was increased and regulated by ERK1/2 (positively) and JNK (negatively), although p38 MAPK activation did not seem to play any significant role in oxidative stress-induced insulin secretion impairment; (ii) the JNK pathway appeared to inhibit both ERK1/2 activation and insulin secretion, although JNK phosphorylation was not significantly changed in our experimental conditions; (iii) the functionality of β-cell in the presence of oxidative stress was closely linked to the level of ERK1/2 activation, (iv) quercetin, resveratrol, or NAC inhibited H2O2 -induced p38 MAPK phosphorylation. The preservation of β-cell function against oxidative stress appears dependent on the balance between ERK1/2 and JNK activation. The protecting effect of quercetin appears due to ERK1/2 hyperactivation, possibly induced by L-type calcium channel opening as we recently showed

COMPOSITIONS COMPRISING UROLITHINS AND USES THEREOF FOR THE STIMULATION OF INSULIN SECRETION

The present invention relates to a composition comprising urolithin A, urolithin B, urolithin C, urolithin D, or a combination thereof, for the stimulation of insulin secretion, and to the use of a compound chosen among urolithin A, urolithin B, urolithin C, urolithin D, or a combination thereof, intended for the stimulation of insulin secretion. The present invention also relates to a composition comprising an effective amount of urolithin B, urolithin C, urolithin D, or a combination thereof, for the treatment or the prevention of diabetes mellitus, and in particular for the treatment or the prevention of type 2 diabetes, and to the use of a compound chosen among urolithin B, urolithin C, urolithin D, and a combination thereof, intended for the treatment or the prevention of diabetes mellitus, and in particular of type 2 diabetes

Effect of glicentin, oxyntomodulin and related peptides on isolated gastric smooth muscle cells

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L’acide chicorique est une molécule antioxydante stimulant la voie AMP Kinase, l’expression de PGC1 α et l’activité mitochondriale dans un modèle de cellules musculaires striées

Poster présenté à la réunion scientifique de la SFD, de la SFD Paramédical et de l'AJD, 26-29/03/2013Introduction : Les antioxydants d’origine alimentaire pourraient prévenir la résistance à l’insuline ainsi que le développement du stress oxydant associé aux maladies métaboliques. Parmi ceux-ci, les polyphénols tels que l’acide caféique et ses dérivés (acide chlorogénique et acide chicorique) posséderaient des propriétés antidiabétiques. Nous avons étudié, sur la lignée de myoblastes L6, l’influence de l’acide chicorique (AC) sur le stress oxydant, l’activité mitochondriale, la voie de l’AMPK (protéine kinase activée par l’AMP) et celle de l’insuline.Matériels et méthodes: L’expression des protéines et des ARNm a été déterminée par Western Blot et qPCR. Les espèces réactives de l’oxygène (ROS) ont été quantifiées avec la sonde 2’,7-dichlorofluoresceine. La captation cellulaire de glucose a été mesurée par l’incorporation de 2-deoxy-D-glucose[3H].Résultats : Dans les myotubes L6, l’AC est un piégeur de ROS en condition basale et en condition de stress oxydant. L’AC augmente l’activité des systèmes de défenses enzymatiques anti-oxydantes glutathion peroxydase et superoxyde dismutase (SOD). Il protège la mitochondrie contre les dommages oxydatifs en augmentant l’expression de la MnSOD. L’AC augmente l’activité du complexe II ainsi que l’expression de PGC-1α impliqué dans la régulation de l’expression des enzymes anti-oxydantes et la biogénèse mitochondriales. L’AC stimule la voie AMPK/ACC et inhibe la voie Akt/mTOR en présence d’insuline, sans modification de la captation de glucose.Conclusion : L’AC possède des propriétés anti-oxydantes, à la fois par sa capacité à neutraliser les ROS et à augmenter les systèmes enzymatiques de défense anti-oxydante. L’AC stimule également la biogénèse mitochondriale et protège les mitochondries contre les dommages oxydatifs, tout en améliorant leur capacité à oxyder les acides gras en stimulant l’AMPK et en augmentant l’activité du complexe II. Ces résultats suggèrent que le potentiel de l’acide chicorique à prévenir ou traiter les pathologies associées au syndrome métabolique mérite d’être étudié de façon plus approfondie

A Total Red Wine Polyphenolic Extract Prevents a Pathological Phenotype Manifested on Cardiomyocytes Isolated from Rats with Nutritionally-induced Metabolic Syndrome

International audienceIsolated cardiomyocyte contractility was explored in a model of metabolic syndrome (the fructose-fed rat) and the effect of a treatment by a total red wine polyphenolic extract (RWPE) determined. Fructose-enriched diet impaired cardiomyocyte maximal shortening and velocities of contraction and relaxation, while RWPE was able to prevent those changes. Those studies suggest that red wine polyphenols are able to prevent the development of a cardiac phenotype commonly observed at an early stage of heart failure

Short-term intravenous insulin infusion is associated with reduced expression of NADPH oxidase p47 phox subunit in monocytes from type 2 diabetes patients

International audienceHyperglycemia is a well-known inducing factor of oxidative stress through activation of NADPH oxidase. In addition to its plasma glucose lowering effect, insulin may also have antioxidant activity and was shown to downregulate NADPH oxidase expression in vitro. In this study, we show that a short-term (3-day) intravenous insulin infusion in patients with type 2 diabetes induces normalization of both glycemia and mRNA expression of circulating monocyte p47(phox) subunit

Quercetin induces insulin secretion by direct activation of L-type calcium channels in pancreatic beta cells

International audienceBackground and Purpose: Quercetin is a natural polyphenolic flavonoid that displays anti‐diabetic properties in vivo. Its mechanism of action on insulin‐secreting beta cells is poorly documented. In this work, we have analysed the effects of quercetin both on insulin secretion and on the intracellular calcium concentration ([Ca2+]i) in beta cells, in the absence of any co‐stimulating factor.Experimental Approach: Experiments were performed on both INS‐1 cell line and rat isolated pancreatic islets. Insulin release was quantified by the homogeneous time‐resolved fluorescence method. Variations in [Ca2+]i were measured using the ratiometric fluorescent Ca2+ indicator Fura‐2. Ca2+ channel currents were recorded with the whole‐cell patch‐clamp technique.Key Results: Quercetin concentration‐dependently increased insulin secretion and elevated [Ca2+]i. These effects were not modified by the SERCA inhibitor thapsigargin (1 μmol·L−1), but were nearly abolished by the L‐type Ca2+ channel antagonist nifedipine (1 μmol·L−1). Similar to the L‐type Ca2+ channel agonist Bay K 8644, quercetin enhanced the L‐type Ca2+ current by shifting its voltage‐dependent activation towards negative potentials, leading to the increase in [Ca2+]i and insulin secretion. The effects of quercetin were not inhibited in the presence of a maximally active concentration of Bay K 8644 (1 μmol·L−1), with the two drugs having cumulative effects on [Ca2+]i.Conclusions and Implications: Taken together, our results show that quercetin stimulates insulin secretion by increasing Ca2+ influx through an interaction with L‐type Ca2+ channels at a site different from that of Bay K 8644. These data contribute to a better understanding of quercetin's mechanism of action on insulin secretion

Chicoric acid is an antioxidant molecule that stimulates AMP kinase pathway in L6 myotubes and extends lifespan in Caenorhabditis elegans.

Chicoric acid (CA) is a caffeoyl derivative previously described as having potential anti-diabetic properties. As similarities in cellular mechanism similarities between diabetes and aging have been shown, we explored on L6 myotubes the effect of CA on the modulation of intracellular pathways involved in diabetes and aging. We also determined its influence on lifespan of Caenorhabditis elegans worm (C. elegans). In L6 myotubes, CA was a potent reactive oxygen species (ROS) scavenger, reducing ROS accumulation under basal as well as oxidative stress conditions. CA also stimulated the AMP-activated kinase (AMPK) pathway and displayed various features associated with AMPK activation: CA (a) enhanced oxidative enzymatic defences through increase in glutathion peroxidase (GPx) and superoxide dismutase (SOD) activities, (b) favoured mitochondria protection against oxidative damage through up-regulation of MnSOD protein expression, (c) increased mitochondrial biogenesis as suggested by increases in complex II and citrate synthase activities, along with up-regulation of PGC-1α mRNA expression and (d) inhibited the insulin/Akt/mTOR pathway. As AMPK stimulators (e.g. the anti-diabetic agent meformin or polyphenols such as epigallocatechingallate or quercetin) were shown to extend lifespan in C. elegans, we also determined the effect of CA on the same model. A concentration-dependant lifespan extension was observed with CA (5-100 μM). These data indicate that CA is a potent antioxidant compound activating the AMPK pathway in L6 myotubes. Similarly to other AMPK stimulators, CA is able to extend C. elegans lifespan, an effect measurable even at the micromolar range. Future studies will explore CA molecular targets and give new insights about its possible effects on metabolic and aging-related diseases