Laboratório de Farmacologia da Dor, Departamento de Farmacologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, 90050-170, Brazil.
Purinergic Signal. 2011 Dec;7(4):373-9. doi: 10.1007/s11302-011-9253-8. Epub 2011 Aug 11.
Extracellular adenosine 5'-triphosphate (ATP) and its breakdown products, adenosine 5'-diphosphate (ADP) and adenosine, have significant effects on a variety of biological processes. NTPDase enzymes, responsible for adenine nucleotides hydrolysis, are considered the major regulators of purinergic signaling in the blood. Previous work by our group demonstrated that ATP and ADP hydrolysis in rat blood serum are higher during the dark (activity) phase compared to the light (rest) phase. In nocturnal animals (e.g., rats), important physiological changes occur during the dark phase, such as increased circulating levels of melatonin, corticosterone, and norepinephrine (NE). This study investigated the physiological effects, in vivo and in vitro, of melatonin, dexamethasone, and NE upon nucleotides hydrolysis in rat blood serum. For in vivo experiments, the animals received a single injection of saline (control), melatonin (0.05 mg/kg), dexamethasone (0.1 mg/kg), or NE (0.03 mg/kg). For in vitro experiments, melatonin (1.0 nM), dexamethasone (1.0 μM), or NE (1.0 nM) was added directly to the reaction medium with blood serum before starting the enzyme assay. The results demonstrated that ATP and ADP hydrolysis in both in vitro and in vivo experiments were significantly higher with NE treatment compared to control (in vitro: ATP = 36.63%, ADP = 22.43%, P < 0.05; in vivo: ATP = 44.1%, ADP = 37.28%, P < 0.001). No significant differences in adenine nucleotides hydrolysis were observed with melatonin and dexamethasone treatments. This study suggests a modulatory role of NE in the nucleotidases pathway, decreasing extracellular ATP and ADP, and suggests that NE might modulate its own release by increasing the activities of soluble nucleotidases.
细胞外三磷酸腺苷 (ATP) 及其分解产物二磷酸腺苷 (ADP) 和腺苷对各种生物过程有重要影响。负责腺嘌呤核苷酸水解的 NTPDase 酶被认为是血液中嘌呤能信号转导的主要调节剂。我们小组的先前工作表明，与光照（休息）期相比，大鼠血清中的 ATP 和 ADP 水解在暗（活动）期更高。在夜间活动的动物（例如大鼠）中，暗期会发生重要的生理变化，例如循环中褪黑素、皮质酮和去甲肾上腺素（NE）水平升高。本研究研究了褪黑素、地塞米松和 NE 对大鼠血清核苷酸水解的体内和体外的生理影响。在体内实验中，动物接受了单次生理盐水（对照）、褪黑素（0.05 mg/kg）、地塞米松（0.1 mg/kg）或 NE（0.03 mg/kg）注射。在体外实验中，在开始酶测定之前，将褪黑素（1.0 nM）、地塞米松（1.0 μM）或 NE（1.0 nM）直接添加到含有血清的反应介质中。结果表明，与对照组相比，NE 处理可显著增加体外和体内实验中 ATP 和 ADP 的水解（体外：ATP = 36.63%，ADP = 22.43%，P < 0.05；体内：ATP = 44.1%，ADP = 37.28%，P < 0.001）。褪黑素和地塞米松处理对腺嘌呤核苷酸水解无显著差异。本研究表明 NE 在核苷酸酶途径中具有调节作用，可减少细胞外 ATP 和 ADP，并表明 NE 可能通过增加可溶性核苷酸酶的活性来调节自身的释放。
