Pozo D, Reiter R J, Calvo J R, Guerrero J M
Department of Medical Biochemistry and Molecular Biology, University of Seville School of Medicine, Spain.
Life Sci. 1994;55(24):PL455-60. doi: 10.1016/0024-3205(94)00532-x.
In the present paper we show the inhibitory effect of melatonin on rat cerebellar nitric oxide synthase (NOS) activity. NO production was monitored by the stoichiometric conversion of L-arginine to L-citrulline. The inhibitory effect of melatonin was dose-dependent, with an IC50 value of about 0.1 mM. However, a significant inhibition of enzyme activity (> 22%) was observed at 1 nM melatonin which is in the range of the physiological serum concentration of the hormone at night. The inhibitory effect of melatonin was observed exclusively in the presence of Ca++. Results suggest a new and important role of the pineal hormone melatonin on central nervous system processes, i.e., by modulating NO production.
在本论文中，我们展示了褪黑素对大鼠小脑一氧化氮合酶（NOS）活性的抑制作用。通过L-精氨酸向L-瓜氨酸的化学计量转化来监测一氧化氮（NO）的生成。褪黑素的抑制作用呈剂量依赖性，半数抑制浓度（IC50）值约为0.1 mM。然而，在1 nM褪黑素时观察到酶活性有显著抑制（> 22%），这处于该激素夜间生理血清浓度范围内。褪黑素的抑制作用仅在有钙离子（Ca++）存在时观察到。结果表明松果体激素褪黑素在中枢神经系统过程中具有新的重要作用，即通过调节NO的生成来发挥作用。
