Laboratory of Molecular Biology and Endocrinology, Institute of Nuclear Sciences "Vinča", University of Belgrade, Belgrade, Serbia.
Neurochem Int. 2013 Sep;63(3):172-9. doi: 10.1016/j.neuint.2013.06.002. Epub 2013 Jun 12.
Exposure of an organism to stress, results in oxidative stress and increased nitric oxide (NO) production in the brain. The role of the processes caused by chronic stress in the prefrontal cortex has not been fully investigated. Considering that chronic stress increases NO production by the enzyme nitric oxide synthase (NOS), we examined the cytosolic neuronal (nNOS) or inducible (iNOS) protein levels in the prefrontal cortex of rats exposed to 21d of chronic social isolation stress, an animal model of depression, alone or in combination with 2h of acute immobilization or cold (4°C) stress (combined stress). Antioxidative status via cytosolic CuZnSOD and mitochondrial MnSOD activity, cytosolic redox status via reduced glutathione (GSH) concentration were determined. Furthermore, cytosolic inducible heat shock protein 70 (Hsp70i), cytosolic/nuclear distributions of NF-κB and serum corticosterone (CORT) were also investigated to elucidate the possible mechanism involved in the cellular NOS pathway. Our results showed that both acute stressors led to increases of CORT and nNOS protein while iNOS protein expression was unaffected. In contrast to the acute stress, chronic social isolation compromised hypothalamic-pituitary-adrenal axis functioning such that the normal stress response was impaired following subsequent acute stressors. Downregulated redox GSH status as well as decreased activity of CuZnSOD and MnSOD suggests the existence of oxidative stress which remained as such following combined stressors. Changes in redox-status associated with decreased Hsp70i protein expression enabled NF-κB translocation into the nucleus, causing increased cytosolic nNOS and iNOS protein expression. Results suggest that NOS signaling pathway plays a differential role between acute and chronic stress whereby state of oxidative/nitrosative stress after chronic social isolation is caused, at least in part, by NF-κB activation and increased iNOS protein expression.
生物体暴露于应激下，会导致氧化应激和脑中一氧化氮（NO）生成增加。慢性应激在额前皮质中引起的过程的作用尚未得到充分研究。考虑到慢性应激会增加一氧化氮合酶（NOS）产生的 NO 生成，我们检查了暴露于 21 天慢性社交隔离应激（抑郁动物模型）的大鼠前额皮质中的细胞溶质神经元（nNOS）或诱导型（iNOS）蛋白水平，单独或与 2 小时急性固定或寒冷（4°C）应激（联合应激）一起。通过细胞溶质 CuZnSOD 和线粒体 MnSOD 活性测定抗氧化状态，通过还原型谷胱甘肽（GSH）浓度测定细胞溶质氧化还原状态。此外，还研究了细胞溶质诱导型热休克蛋白 70（Hsp70i）、细胞溶质/核 NF-κB 和血清皮质酮（CORT）的分布，以阐明细胞 NOS 途径中涉及的可能机制。我们的结果表明，两种急性应激源均导致 CORT 和 nNOS 蛋白增加，而 iNOS 蛋白表达不受影响。与急性应激相反，慢性社交隔离会损害下丘脑-垂体-肾上腺轴的功能，从而使随后的急性应激源的正常应激反应受损。下调的氧化还原 GSH 状态以及 CuZnSOD 和 MnSOD 活性的降低表明存在氧化应激，而联合应激源后仍保持不变。与 Hsp70i 蛋白表达降低相关的氧化还原状态变化使 NF-κB 易位到细胞核，导致细胞溶质 nNOS 和 iNOS 蛋白表达增加。结果表明，NOS 信号通路在急性和慢性应激之间发挥不同的作用，慢性社交隔离后氧化/硝化应激的状态至少部分是由 NF-κB 激活和 iNOS 蛋白表达增加引起的。
