PPAR-gamma agonist inhibits Ang II-induced activation of dendritic cells via the MAPK and NF-kappaB pathways.

The renin-angiotensin system exerts a profound regulatory effect on the functional features of dendritic cells (DCs), thus suggesting a new target of angiotensin II (Ang II) action in the immune system. This study analyzed whether peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activation in DCs regulated Ang II-induced activation of DCs and exploited the possible molecular mechanisms, especially focused on the signaling pathways of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-kappaB). Ang II stimulation of human monocyte-derived DCs resulted in an intermediate state of DC maturation and function via modulating the balance of the negative or positive regulation of the signaling pathways of extracellular regulated kinase (ERK), p38 MAPK and NF-kappaB, but not c-Jun N-terminal kinase (JNK). Moreover, pretreatment of DCs with the PPAR-gamma agonist pioglitazone reverted these effects of Ang II on DCs via suppression of the MAPK and NF-kappaB signaling pathways at least in part. Collectively, our data support the notion that PPAR-gamma activation in human DCs inhibits the activation of DCs induced by Ang II, with which involves the regulation of MAPK and NF-kappaB signaling pathways. These findings may support the important role of these mediators in the regulation of DC-mediated inflammatory and immunologic processes.

Delayed electrical uncoupling is involved in kappa-opioid receptor activation -induced cardioprotective effect in the isolated rat heart / 中国应用生理学杂志

<p><b>AIM</b>To determine whether activation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical uncoupling during prolonged ischemia and whether these changes in electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation, and to explore the possible mechanism.</p><p><b>METHODS</b>(1) To observe the effect of U50,488H (10(-7), 10(-6), 3 x10(-6) and 10(-5) mol/L), a selective kappa-opioid receptor agonist, or with a selective kappa-opioid receptor antagonist nor-BNI (5 x 10(-6) mol/L), or with a mitochondrial K(ATP) channel inhibitor 5-HD on myocardium during ischemia/reperfusion in isolated perfused rat heart. Parameters of measurements include hemodynamic data, formazan content, heart rate, coronary flow, and lactate dehydrogenase (LDH). (2) To examine the effect of U50,488H of different concentration on electrical coupling parameters (including onset of uncoupling, plateau time, slope, and fold increase in r1) during 70 min myocardial ischemia in isolated perfused rat heart.</p><p><b>RESULTS</b>(1) Pretreatment with U50,488H concentration dependently increased formazan content and reduced LDH release induced by 30 min of ischemia and 120 min of reperfusion. (2) The onset of electrical uncoupling and plateau time during prolonged ischemia was delayed by kappa-opioid receptor activation with U50,488H. (3) Linear regression analysis shown that the increase in formazan content and decrease in LDH release produced by kappa-opioid receptor activation was associated with delayed electrical uncoupling during prolonged ischemia. (4) The effects of U50,488H on formazan content, LDH release and on electrical coupling were abolished by nor-BNI, or 5-HD.</p><p><b>CONCLUSION</b>This results demonstrate that the onset of electrical uncoupling during prolonged ischemia is delayed by kappa-opioid receptor activation with a selective kappa-opioid receptor agonist U50,488H, and that delayed electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation with U50,488H. These effects of kappa-opioid receptor activation with U50,488H are mediated by mitochondrial K(ATP) channels.</p>