研究表明，应激能够引起海马功能紊乱，从而导致海马神经元死亡，最终引起各种神经退行性疾病。脂多糖（lipopolysaccharide，LPS）、海人酸（kainic acid，KA）引起的海马神经元急性应激损伤与NO/NOS系统的活化有关。啮齿动物上的研究表明，姜黄素（Curcumin, CUR）能够缓解动物的慢性应激，也可以通过调节海马中NO的合成缓解LPS或KA引起的海马神经元损伤。猪的短途运输是一种亚急性应激，这种应激是否可能导致海马NO-NOS系统活性发生改变，而CUR是否可能通过调节海马NO-NOS系统缓解猪的运输应激尚不清楚。因此，本试验旨在研究：（1）2 h运输是否导致猪海马NO-NOS系统活性的变化；（2）运输前饲喂姜黄素21天是否能够逆转或缓解运输应激状态下猪海马NO-NOS系统功能的变化；（3）通过猪原代海马神经元培养，分析CUR是否对神经元NO-NOS系统具有直接作用。 1 饲喂CUR对运输应激状态下猪海马NO-NOS系统的影响 采用18头皮特兰×二花脸F2代雄性仔猪，断奶后随机分成三组：对照组（CON）（饲喂21 d基础日粮）、运输对照组（T-CON）（饲喂21 d的基础日粮，然后进行2 h运输）以及饲喂CUR组（CUR）（连续21 d每天口服8 mg/kg.BW姜黄素，然后与T-CON组同时进行2 h的运输）。运输结束后，用电击的方法将猪致昏，迅速采集血液、海马样本。测定不同处理组血浆皮质醇水平及海马NO-NOS系统的变化。结果显示：2 h的运输极显著增加血浆皮质醇的水平（P < 0.01）；CUR能够明显缓解运输应激导致的血浆皮质醇极显著升高（P < 0.05）。2 h的运输引起海马NO含量显著增加（P < 0.05），海马神经型一氧化氮合酶（nNOS）mRNA与内皮型一氧化氮合酶（eNOS）mRNA 表达显著上调（P < 0.05），总一氧化氮合酶（T-NOS）、诱导型一氧化氮合酶（iNOS）活力和结构型一氧化氮合酶（cNOS）活力显著增加（P < 0.05）；CUR完全逆转了运输应激导致的NO合成增加和cNOS活力的显著上调（P < 0.05），缓解了由应激导致的nNOS、eNOS mRNA表达和T-NOS活力的显著上调。这些结果表明：CUR可逆转或缓解运输应激导致的猪海马NO/NOS系统活化。 2 姜黄素预处理对基础和应激状态下猪海马神经元活力和NO-NOS系统的影响 采用猪原代海马神经元体外培养，研究CUR预处理对地塞米松（DEX）引起的神经元损伤的保护作用，并观察NO-NOS系统是否参与CUR的作用。通过MTT法检测细胞活力；采用NO检测试剂盒与NOS检测试剂盒检测细胞上清NO含量和细胞中NOS活力。结果显示，DEX处理24 h显著降低神经元活力（P < 0.05），但是10 µM CUR预处理24 h显著逆转了DEX导致的细胞活力下降（P < 0.05）。10 µM DEX处理神经元24 h后，神经元NO水平显著升高（P < 0.05），T-NOS、iNOS和cNOS活力显著升高（P < 0.05）；CUR预处理显著降低了DEX诱导的NO水平升高（P < 0.05）以及T-NOS和cNOS活力的增加（P < 0.05），而对DEX引起的iNOS活力升高没有表现出抑制作用。以上结果提示，CUR预处理可通过调节NO-NOS系统活性对DEX诱导的神经元损伤起到直接的保护作用。

Previous studies demonstrated that stress causes dysfunction of hippocampus, and leads to neuron death which eventually results in a variety of neurodegenerative diseases. Lipopolysaccharide (LPS) or kainic acid (KA)-induced acute hippocampal neurodegenesis are associated with activation of hippocampal NO-NOS system. Studies on rodents indicated that curcumin (CUR) can alleviate the chronic stress and attenuates neuronal damage induced by LPS or KA through regulating hippocampal NO synthesis. The short distance transport is a subacute stress in pigs. It is not clear whether 2 h transport can induce activation of hippocampal NO-NOS system, and whether CUR may alleviate transport stress-induced responses in hippocampal NO-NOS system in pigs. Herein, this study was aimed to investigate (1) whether 2 h transport could lead to activation of hippocampal NO-NOS system in pigs; (2) whether feeding CUR for 21 days could reverse or attenuate stress-induced changes in hippocampal NO-NOS system in pigs; (3) whether CUR plays direct protective roles on primary porcine hippocampal neurons under the challenge of dexamethasone (DEX) in vitro. 1 Effects of CUR on hippocampal NO-NOS system in pigs subjected to transport stress 18 male Pietrain×Erhualian F2 piglets were randomly divided into three groups: control group (CON) fed basic diet for 21 d, tranport control group (T-CON) fed basal diet for 21 d, then subjected to 2 h transport, CUR group (CUR) was administered orally 8 mg/kg.BW of CUR per day successively for 21 d, then subjected to 2 h transport together with T-CON. After 2 h transport, piglets were sacrificed with electric shock. Serum and hippocampus were collected for analysing serum cortisol levels and variations in hippocampal NO-NOS system. 2 h tranport significantly increased serum cortisol level (P < 0.01), CUR effectively attenuated transport stress-induced elevation of serum cortisol production (P < 0.05). Transport led to significant increase of NO production in hippocampus (P < 0.05), together with significantly (P < 0.05) enhanced hippocampal mRNA expression of nNOS and eNOS, as well as increased (P < 0.05) activity of T-NOS, iNOSand cNOS. CUR totally reversed stress-induced hippocampal NO production, which was in line with completely reversed cNOS activity, and diminished mRNA expression of nNOS and eNOS, as well as T-NOS activity. The results indicated that CUR reverses or attenuates the activation of hippocampal NO-NOS induced by transport stress in pigs. 2 Effect of curcumin pretreatment on viability and NO-NOS system of primary cultural hippocampal neurons exposed to dexamethasone The neuroprotective roles of CUR pretreatment was investigated in primary culture of porcine hippocampal neurons exposed to DEX for 24 h. Cell viability was detected by MTT assay and NO production in culture medium and NOS activity in cell lysates were determined with NO assay kit and NOS assay kit respectively. Cell viability was significantly decreased in DEX-treated neurons (P < 0.05), 24 h of pretreatment with 10 µM CUR reversed DEX-induced decrease in cell viability. DEX exposure resulted in significant increase in NO level in hippocampus (P < 0.05), which was associated with up-regulated enzyme activities of T-NOS, iNOS and cNOS (P < 0.05). CUR pretreatment prevented DEX-induced NO production and T-NOS, cNOS activation (P < 0.05), but not iNOS up-regulation. The results indicated that CUR plays direct neuroprotective roles in primary hippocampal neurons under DEX challenge through modulating NO-NOS system.