Mitochondrial uncoupler BAM15 inhibits artery constriction and potently activates AMPK in vascular smooth muscle cells

Our previous studies found that mitochondrial uncouplers CCCP and niclosamide inhibited artery constriction and the mechanism involved AMPK activation in vascular smooth muscle cells. BAM15 is a novel type of mitochondrial uncoupler. The aim of the present study is to identify the vasoactivity of BAM15 and characterize the BAM15-induced AMPK activation in vascular smooth muscle cells(A10 cells). BAM15 relaxed phenylephrine(PE)-induced constricted rat mesenteric arteries with intact and denuded endothelium. Pretreatment with BAM15 inhibited PEinduced constriction of rat mesenteric arteries with intact and denuded endothelium. BAM15, CCCP,and niclosamide had the comparable IC50 value of vasorelaxation in PE-induced constriction of rat mesenteric arteries. BAM15 was less cytotoxic in A10 cells compared with CCCP and niclosamide.BAM15 depolarized mitochondrial membrane potential, induced mitochondrial fission, increased mitochondrial ROS production, and increased mitochondrial oxygen consumption rate in A10 cells.BAM15 potently activated AMPK in A10 cells and the efficacy of BAM15 was stronger than that of CCCP, niclosamide, and AMPK positive activators metformin and AICAR. In conclusion, BAM15 activates AMPK in vascular smooth muscle cells with higher potency than that of CCCP, niclosamide and the known AMPK activators metformin and AICAR. The present work indicates that BAM15 is a potent AMPK activator.

Arterial relaxation is coupled to inhibition of mitochondrial fission in arterial smooth muscle cells:comparison of vasorelaxant effects of verapamil and phentolamine

Mitochondria are morphologically dynamic organelles which undergo fission and fusion processes. Our previous study found that arterial constriction was always accompanied by increased mitochondrial fission in smooth muscle cells, whereas inhibition of mitochondrial fission in smooth muscle cells was associated with arterial relaxation. Here, we used the typical vasorelaxants, verapamil and phentolamine, to further confirm the coupling between arterial constriction and mitochondrial fission in rat aorta. Results showed that phentolamine but not verapamil induced vasorelaxation in phenylephrine(PE)-induced rat thoracic aorta constriction. Verapamil, but not phentolamine, induced vasorelaxation in high K^+(KPSS)-induced rat thoracic aorta constriction. Pre-treatment with phentolamine prevented PEbut not KPSS-induced aorta constriction and pre-treatment with verapamil prevented both PE-and KPSSinduced aorta constriction. Transmission electron microscopy(TEM) results showed that verapamil but not phentolamine inhibited KPSS-induced excessive mitochondrial fission in aortic smooth muscle cells,and verapamil prevented both PE-and KPSS-induced excessive mitochondrial fission in aortic smoothmuscle cells. Verapamil inhibited KPSS-induced excessive mitochondrial fission in cultured vascular smooth muscle cells(A10). These results further demonstrate that arterial relaxation is coupled to inhibition of mitochondrial fission in arterial smooth muscle cells.

Mitochondrial uncoupler triclosan induces vasorelaxation of rat arteries

Our previous studies found that mitochondrial uncouplers induced vasodilation. Triclosan, the broad spectrum antibacterial agent, is the active ingredient in soaps and toothpastes. It was reported that triclosan induced mitochondrial uncoupling, so we aim to investigate the effects of triclosan on vascular function of rat mesenteric arteries and aorta. The isometric tension of rat mesenteric artery and thoracic aorta was recorded by multi-wire myograph system. The cytosolic [Ca^(2+)]_i, mitochondrial reactive oxygen species(mitoROS), and mitochondrial membrane potential of smooth muscle cells(A10 cells) were measured using laser scanning confocal microscopy. Triclosan treatment relaxed phenylephrine(PE)-and high K^(+)(KPSS)-induced constriction, and pre-treatment with triclosan inhibited PE-and KPSS-induced constriction of rat mesenteric arteries. In rat thoracic aorta, triclosan also relaxed PE-and KPSS-induced constriction. Triclosan induces vasorelaxation without involving KATPchannel activation in smooth muscle cells of arteries.Triclosan treatment increased cytosolic [Ca^(2+)]_i, mitochondrial ROS production and depolarized mitochondrial membrane potential in A10 cells. In conclusion, triclosan induces mitochondrial uncoupling in vascular smooth muscle cells and relaxes the constricted rat mesenteric arteries and aorta of rats. The present results suggest that triclosan would indicate vasodilation effect if absorbed excessively in vivo.

DMH1(4-[6-(4-isopropoxyphenyl)pyrazolo[1,5-a]pyrimidin-3-yl]quinoline) inhibits chemotherapeutic drug-induced autophagy

Our previous work found that DMH1(4-[6-(4-isopropoxyphenyl)pyrazolo [1,5-a]pyrimidin-3-yl]quinoline) was a novel autophagy inhibitor. Here, we aimed to investigate the effects of DMH1 on chemotherapeutic drug-induced autophagy as well as the efficacy of chemotherapeutic drugs in different cancer cells. We found that DMH1 inhibited tamoxifen- and cispcis-diaminedichloroplatinum(II)(CDDP)-induced autophagy responses in MCF-7 and HeLa cells, and potentiated the anti-tumor activity of tamoxifen and CDDP for both cells. DMH1 inhibited 5-fluorouracil(5-FU)-induced autophagy responses in MCF-7 and HeLa cells, but did not affect the anti-tumor activity of 5-FU for these two cell lines. DMH1 itself did not induce cell death in MCF-7 and HeLa cells, but inhibited the proliferation of these cells. In conclusion, DMH1 inhibits chemotherapeutic drug-induced autophagy response and the enhancement of efficacy of chemotherapeutic drugs by DMH1 is dependent on the cell sensitivity to drugs.

5-HT_(3) receptor antagonists protect against pressure overload-induced cardiac hypertrophy in murine

Activation of cardiac sympathetic afferent reflex results in the increase of sympathetic activity.Serotonin(5-HT)activates cardiac sympathetic afferent through stimulating 5-HT_(3) receptors,the aim of present study is to test whether 5-HT_(3) receptor antagonists protect against cardiac hypertrophy.Cardiac hypertrophy induced by TAC for 4 weeks in mice was significantly inhibited by administration of 5-HT_(3) receptor antagonists,ondansetron(2.5 mg/kg,ip.)or tropisetron(2.5 mg/kg,ip.).Histological analysis revealed that the increased cardiac fibrosis in hypertrophic heart was relieved by ondansetron or tropisetron treatment.Ondansetron or tropisetron reduced the elevated plasma level of noradrenalin in mice with cardiac hypertrophy.Ondansetron and tropisetron had no effect on cardiomyocte hypertrophy induced by phenylephrine treatment in vitro.Finally,we took tropisetron as the representative drug and examined the effects of tropisetron on the desensitization of cardiac b-adrenergic receptor in rat treated with abdominal aortic banding(AB).Results showed that tropisetron restored the desensitization of cardiac b-adrenergic receptor in AB-treated rats.In conclusion,5-HT_(3) receptor antagonists protected against cardiac hypertrophy and restored the desensitization of cardiac adrenergic responsiveness,the mechanism in which may be through reducing the sympathetic activity.

Anthelmintics nitazoxanide protects against experimental hyperlipidemia and hepatic steatosis in hamsters and mice

Lipid metabolism disorders contribute to hyperlipidemia and hepatic steatosis.It is ideal to develop drugs simultaneous improving both hyperlipidemia and hepatic steatosis.Nitazoxanide is an FDA-approved oral antiprotozoal drug with excellent pharmacokinetic and safety profile.We found that nitazoxanide and its metabolite tizoxanide induced mild mitochondrial uncoupling and subsequently activated AMPK in Hep G2 cells.Gavage administration of nitazoxanide inhibited high-fat diet(HFD)-induced increases of liver weight,blood and liver lipids,and ameliorated HFD-induced renal lipid accumulation in hamsters.Nitazoxanide significantly improved HFD-induced histopathologic changes of hamster livers.In the hamsters with pre-existing hyperlipidemia and hepatic steatosis,nitazoxanide also showed therapeutic effect.Gavage administration of nitazoxanide improved HFD-induced hepatic steatosis in C57BL/6J mice and western diet(WD)-induced hepatic steatosis in Apoe-/-mice.The present study suggests that repurposing nitazoxanide as a drug for hyperlipidemia and hepatic steatosis treatment is promising.

The clinical antiprotozoal drug nitazoxanide and its metabolite tizoxanide extend Caenorhabditis elegans lifespan and healthspan

The drugs extending healthspan in clinic have always been searched.Nitazoxanide is an FDA-approved clinical antiprotozoal drug.Nitazoxanide is rapidly metabolized to tizoxanide after absorption in vivo.Our previous studies find that nitazoxanide and its metabolite tizoxanide induce mild mitochondrial uncoupling and activate cellular AMPK,oral nitazoxanide protects against experimental hyperlipidemia,hepatic steatosis,and atherosclerosis.Here,we demonstrate that both nitazoxanide and tizoxanide extend the lifespan and healthspan of Caenorhabditis elegans through Akt/AMPK/sir 2.1/daf16 pathway.Additionally,both nitazoxanide and tizoxanide improve high glucose-induced shortening of C.elegans lifespan.Nitazoxanide has been a clinical drug with a good safety profile,we suggest that it is a novel anti-aging drug.