Jesko Henryk, Chalimoniuk Malgorzata, Strosznajder Joanna B
Department of Cellular Signalling, Medical Research Centre, Polish Academy of Sciences, 5 Pawinskiego St. PL-02106 Warsaw, Poland.
Neurochem Int. 2003 Mar;42(4):315-22. doi: 10.1016/s0197-0186(02)00098-0.
In this study, the effect of aging on nitric oxide synthases (NOS) was investigated in homogenates and cytosolic fractions from hippocampus, brain cortex and cerebellum of adult, old adult and old Wistar rats (3-4, 14, and 24 months old, respectively). Our results indicate the enhancement of Ca(2+) and calmoduline-dependent NOS activity in all investigated aged brain parts. Significantly higher NOS activity was found in the cerebellum. In the absence of Ca(2+) or in the presence of N-nitro-L-arginine (NNLA) the activity of NOS was absent. Inhibitor of constitutive NOS isoforms which preferentially inhibits neuronal NOS (nNOS), 7-nitroindazole, decreased NOS activity by 60 and 75% in adult and aged brain, respectively. However, using RT-PCR a significantly lower amount of mRNA for nNOS was detected in hippocampus. The ratio of NOS activity to nNOS mRNA was significantly higher in hippocampus and cerebellum of aged brain. No expression of the gene for inducible NOS was observed in adult and aged brain. These results indicate that probably nNOS is responsible for higher NOS activity in aged brain. Our data suggest that alteration of nNOS phosphorylation state may be responsible for the activation of NOS in aged brain. The down-regulation of nNOS mRNA expression may be an adaptive mechanism that protects the brain against excessive NO release.
在本研究中，我们调查了衰老对成年、老年成年和老年Wistar大鼠（分别为3 - 4个月、14个月和24个月大）海马体、大脑皮层和小脑匀浆及胞质组分中一氧化氮合酶（NOS）的影响。我们的结果表明，在所有被研究的老龄脑区中，钙（Ca²⁺）和钙调蛋白依赖性NOS活性增强。在小脑中发现NOS活性显著更高。在无Ca²⁺或存在N - 硝基 - L - 精氨酸（NNLA）的情况下，NOS活性缺失。优先抑制神经元型NOS（nNOS）的组成型NOS亚型抑制剂7 - 硝基吲唑，分别使成年和老龄脑区的NOS活性降低60%和75%。然而，使用逆转录 - 聚合酶链反应（RT - PCR）检测到海马体中nNOS的mRNA量显著更低。老龄脑区海马体和小脑中NOS活性与nNOS mRNA的比率显著更高。在成年和老龄脑中未观察到诱导型NOS基因的表达。这些结果表明，可能nNOS是老龄脑区中较高NOS活性的原因。我们的数据表明，nNOS磷酸化状态的改变可能是老龄脑区中NOS激活的原因。nNOS mRNA表达的下调可能是一种保护大脑免受过量一氧化氮释放的适应性机制。
