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The photodynamic and direct actions of methylene blue on mitochondrial energy metabolism: A balance of the useful and harmful effects of this photosensitizer.
Free Radical Biology and Medicine ( IF 7.1 ) Pub Date : 2020-04-18 , DOI: 10.1016/j.freeradbiomed.2020.04.015
Eduardo Makiyama Klosowski 1 , Byanca Thais Lima de Souza 1 , Marcio Shigueaki Mito 1 , Renato Polimeni Constantin 2 , Gislaine Cristiane Mantovanelli 1 , Juliana Morais Mewes 1 , Paulo Francisco Veiga Bizerra 1 , Paulo Vinicius Moreira da Costa Menezes 1 , Eduardo Hideo Gilglioni 1 , Karina Sayuri Utsunomiya 1 , Rogério Marchiosi 2 , Wanderley Dantas Dos Santos 2 , Osvaldo Ferrarese Filho 2 , Wilker Caetano 3 , Paulo Cesar de Souza Pereira 3 , Renato Sonchini Gonçalves 3 , Jorgete Constantin 1 , Emy Luiza Ishii-Iwamoto 1 , Rodrigo Polimeni Constantin 1
Affiliation  

According to the literature, methylene blue (MB) is a photosensitizer (PS) with a high affinity for mitochondria. Therefore, several studies have explored this feature to evaluate its photodynamic effects on the mitochondrial apoptotic pathway under normoxic conditions. We are aware only of limited reports regarding MB's photodynamic effects on mitochondrial energy metabolism, especially under hypoxic conditions. Thus, the purposes of this study were to determine the direct and photodynamic acute effects of MB on the energy metabolism of rat liver mitochondria under hypoxic conditions and its direct acute effects on several parameters linked to energy metabolism in the isolated perfused rat liver. MB presented a high affinity for mitochondria, irrespective of photostimulation or proton gradient formation. Upon photostimulation, MB demonstrated high in vitro oxidizing species generation ability. Consequently, MB damaged the mitochondrial macromolecules, as could be evidenced by the elevated levels of lipid peroxidation and protein carbonyls. In addition to generating a pro-oxidant environment, MB also led to a deficient antioxidant defence system, as indicated by the reduced glutathione (GSH) depletion. Bioenergetically, MB caused uncoupling of oxidative phosphorylation and led to photodynamic inactivation of complex I, complex II, and F1FO-ATP synthase complex, thus decreasing mitochondrial ATP generation. Contrary to what is expected for an ideal PS, MB displayed appreciable dark toxicity on mitochondrial energy metabolism. The results indicated that MB acted via at least three mechanisms: direct damage to the inner mitochondrial membrane; uncoupling of oxidative phosphorylation; and inhibition of electron transfer. Confirming the impairment of mitochondrial energy metabolism, MB also strongly inhibited mitochondrial ATP production. In the perfused rat liver, MB stimulated oxygen consumption, decreased the ATP/ADP ratio, inhibited gluconeogenesis and ureogenesis, and stimulated glycogenolysis, glycolysis, and ammoniagenesis, fully corroborating its uncoupling action in intact cells, as well. It can be concluded that even under hypoxic conditions, MB is a PS with potential for photodynamic effect-induced mitochondrial dysfunction. However, MB disrupts the mitochondrial energy metabolism even in the dark, causing energy-linked liver metabolic changes that could be harmful in specific circumstances.

中文翻译:

亚甲基蓝对线粒体能量代谢的光动力和直接作用:这种光敏剂的有用和有害作用之间的平衡。

根据文献,亚甲基蓝(MB)是对线粒体具有高亲和力的光敏剂(PS)。因此,几项研究探索了该特征,以评估其在常氧条件下对线粒体凋亡途径的光动力作用。我们仅了解到有关MB对线粒体能量代谢的光动力学影响的报道有限,特别是在低氧条件下。因此,本研究的目的是确定低氧条件下MB对大鼠肝线粒体能量代谢的直接和光动力急性影响,以及对离体灌流大鼠肝脏中与能量代谢相关的几个参数的直接急性影响。MB对线粒体具有高亲和力,而与光刺激或质子梯度形成无关。经过光刺激,MB显示出高的体外氧化物质生成能力。因此,MB破坏了线粒体大分子,脂质过氧化和蛋白羰基的水平升高可以证明这一点。除产生促氧化剂环境外,MB还导致缺乏的抗氧化剂防御系统,如减少的谷胱甘肽(GSH)消耗所示。从生物能角度看,MB引起氧化磷酸化的解偶联并导致复合物I,复合物II和F1FO-ATP合酶复合物的光动力学失活,从而减少了线粒体ATP的产生。与理想PS的预期相反,MB对线粒体能量代谢显示出明显的暗毒性。结果表明,MB通过至少三种机制起作用:直接损伤线粒体内膜;直接破坏线粒体内膜。氧化磷酸化解偶联;和抑制电子转移。MB证实了线粒体能量代谢的损害,也强烈抑制了线粒体ATP的产生。在灌注的大鼠肝脏中,MB刺激耗氧量,降低ATP / ADP比,抑制糖异生和尿毒症,并刺激糖原分解,糖酵解和氨生成,也充分证实了其在完整细胞中的解偶联作用。可以得出结论,即使在低氧条件下,MB也是具有光动力学效应引起的线粒体功能障碍的潜力的PS。然而,即使在黑暗中,MB也会破坏线粒体能量代谢,导致能量相关的肝脏代谢变化,这在特定情况下可能是有害的。MB证实了线粒体能量代谢的损害,也强烈抑制了线粒体ATP的产生。在灌注的大鼠肝脏中,MB刺激耗氧量,降低ATP / ADP比,抑制糖异生和尿毒症,并刺激糖原分解,糖酵解和氨生成,也充分证实了其在完整细胞中的解偶联作用。可以得出结论,即使在低氧条件下,MB也是具有光动力效应引起的线粒体功能障碍的潜力的PS。然而,即使在黑暗中,MB也会破坏线粒体能量代谢,导致能量相关的肝脏代谢变化,在特定情况下可能有害。MB证实了线粒体能量代谢的损害,也强烈抑制了线粒体ATP的产生。在灌注的大鼠肝脏中,MB刺激耗氧量,降低ATP / ADP比,抑制糖异生和尿毒症,并刺激糖原分解,糖酵解和氨生成,也充分证实了其在完整细胞中的解偶联作用。可以得出结论,即使在低氧条件下,MB也是具有光动力学效应引起的线粒体功能障碍的潜力的PS。然而,即使在黑暗中,MB也会破坏线粒体能量代谢,导致能量相关的肝脏代谢变化,这在特定情况下可能是有害的。降低了ATP / ADP比率,抑制了糖异生和尿毒症,并刺激了糖原分解,糖酵解和氨生成,也充分证实了其在完整细胞中的解偶联作用。可以得出结论,即使在低氧条件下,MB也是具有光动力学效应引起的线粒体功能障碍的潜力的PS。然而,即使在黑暗中,MB也会破坏线粒体能量代谢,导致能量相关的肝脏代谢变化,这在特定情况下可能是有害的。降低了ATP / ADP比率,抑制了糖异生和尿毒症,并刺激了糖原分解,糖酵解和氨生成,也充分证实了其在完整细胞中的解偶联作用。可以得出结论,即使在低氧条件下,MB也是具有光动力学效应引起的线粒体功能障碍的潜力的PS。然而,即使在黑暗中,MB也会破坏线粒体能量代谢,导致能量相关的肝脏代谢变化,在特定情况下可能有害。
更新日期:2020-04-20
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