Catania Maria Vincenza, Giuffrida Raffaella, Seminara Giovanna, Barbagallo Giuseppe, Aronica Eleonora, Gorter Jan A, Dell'Albani Paola, Ravagna Agrippino, Calabrese Vittorio, Giuffrida-Stella Anna Maria
Institute of Neurological Sciences, National Research Council, section of Catania, vl. Regina Margherita 6, 95125 Catania, Italy.
Neurochem Res. 2003 Apr;28(3-4):607-15. doi: 10.1023/a:1022841911265.
Neuronal nitric oxide synthase (nNOS) is a constitutively expressed and calcium-dependent enzyme. Despite predominantly expressed in neurons, nNOS has been also found in astrocytes, although at lower expression levels. We have studied the regulation of nNOS expression in cultured rat astrocytes from cortex and spinal cord by Western blotting and immunocytochemistry. nNOS was not detectable in cultured astrocytes grown in serum-containing medium (SCM), but was highly expressed after serum deprivation. Accordingly, calcium-dependent NOS activity and both intracellular nitrite levels and nitrotyrosine immunoreactivity after glutamate stimulation were higher in serum-deprived astrocytes than in cells grown in SCM. Serum deprivation induced a modification of astrocytes morphology, from flat to stellate. nNOS up-regulation was also observed in reactive astrocytes of rat hippocampi after electrically induced status epilepticus, as demonstrated by double-labeling experiments. Thus, nNOS upregulation occurs in both in vitro stellate and in vivo reactive astrocytes, suggesting a possible involvement of glial nNOS in neurological diseases characterized by reactive gliosis.
神经元型一氧化氮合酶（nNOS）是一种组成性表达且依赖钙的酶。尽管主要在神经元中表达，但在星形胶质细胞中也发现了nNOS，不过其表达水平较低。我们通过蛋白质印迹法和免疫细胞化学研究了来自大鼠皮层和脊髓的培养星形胶质细胞中nNOS表达的调控。在含血清培养基（SCM）中培养的星形胶质细胞中检测不到nNOS，但在血清剥夺后高表达。相应地，血清剥夺的星形胶质细胞中，谷氨酸刺激后的钙依赖性一氧化氮合酶活性以及细胞内亚硝酸盐水平和硝基酪氨酸免疫反应性均高于在SCM中培养的细胞。血清剥夺导致星形胶质细胞形态从扁平变为星状。电诱导癫痫持续状态后，大鼠海马的反应性星形胶质细胞中也观察到nNOS上调，双标记实验证明了这一点。因此，nNOS上调发生在体外星状和体内反应性星形胶质细胞中，提示胶质nNOS可能参与以反应性胶质增生为特征的神经疾病。
