褪黑素对老年大鼠弓状核神经元影响的光镜、电镜定量研究

目的 探讨褪黑素延缓神经元衰老的作用。方法 40只老年 SD大鼠随机分为老年组和褪黑素组 ,2 0只成年 SD大鼠为对照组 ,采用光镜、电镜技术和体视学方法对褪黑素延缓老年大鼠弓状核神经元衰老作用进行了形态定量研究。结果 1三组间弓状核神经元的面积分数、面数密度、胞体和胞核的等效直径无显著变化 (P >0 .0 5) ;2老年组弓状核暗神经元内线粒体和溶酶体的体积分数和面数密度明显增加 (P <0 .0 5) ,粗面内质网、高尔基复合体、游离核糖体和分泌颗粒的体积分数和面数密度显著下降 (P <0 .0 5) ;3褪黑素组与对照组之间 ,弓状核暗细胞内细胞器和分泌颗粒的体积分数和面数密度无显著性差异 (P >0 .0 5)。结论 1衰老引起神经内分泌功能紊乱可能与弓状核神经元的衰老直接相关 ;2褪黑素具有延缓弓状核神经元衰老的作用。

No effect of exogenous melatonin on development of cryopreserved metaphase Ⅱ oocytes in mouse

Background： This study was conducted to investigate effect of exogenous melatonin on the development of mouse mature oocytes after cryopreservation. Results： First, mouse metaphase II （MII） oocytes were vitrified in the open-pulled straws （OPS）. After warming, they were cultured for 1 h in M2 medium containing melatonin at different concentrations （0, 10-9, 10-7, 10-s, 10 3 mol/L）. Then the oocytes were used to detect reactive oxygen species （ROS） and glutathione （GSH） levels （fluorescence microscopy）, and the developmental potential after parthenogenetic activation. The experimental results showed that the ROS level and cleavage rate in 10-3 mol/L melatonin group was significantly lower than that in melatonin-free group （control）. The GSH levels and blastocyst rates in all melatonin-treated groups were similar to that in control. Based on the above results, we detected the expression of gene Hsp9Oaal, Hsfl, Hspalb, Nrf2 and Bcl-xl with qRT-PCR in oocytes treated with 10-7, or 10-3 mol/L melatonin and untreated control. After warming and culture for 1 h, the oocytes showed higher Hsp90oal expression in 10-7 mol/L melatonin-treated group than in the control （P 〈 0.05）; the Hsfl, Hsp9Oaal and Bcl-xl expression were significantly decreased in 10-3 mol/L melatonin-treated group when compared to the control. Based on the above results and previous research, we detected the development of vitrified-warmed oocytes treated with either 10-7 or 0 mol/L melatonin by in vitro fertilization. No difference was observed between them. Conclusions： Our results indicate that the supplementation of melatonin （10-9 to 10-3 mol/L） in culture medium and incubation for 1 h did not improve the subsequent developmental potential of vitrified-warmed mouse MII oocytes, even if there were alteration in gene expression.

外源褪黑素对低温胁迫下大豆V1期幼苗光合荧光及抗氧化系统的影响

为缓解东北春大豆产区大豆苗期低温冷害,通过研究外源褪黑素(melatonin,MT)处理对低温胁迫下大豆耐冷性的影响,明确MT提高大豆耐冷能力的作用途径及适宜浓度。以绥农26为供验试材,设置盆栽培养,在大豆V1期(一节期)叶面喷施不同浓度MT(0、50、100、200μmol·L-1),3 d后进行4℃低温处理,5 d后取样分析低温胁迫下喷施不同浓度MT对V1时期大豆光合特性、活性氧代谢、渗透调节物质的影响。结果表明,较低温胁迫不喷施MT相比,喷施MT处理能增强低温胁迫下叶片光合作用,Pn、Gs、Tr及光合色素含量均显著提高,且随着外源MT浓度增加呈先上升后下降趋势,Chl a/b显著下降;保护酶SOD(超氧化物歧化酶)、POD(过氧化物酶)、CAT(过氧化氢酶)、APX(抗坏血酸过氧化物酶)活性、Pro(脯氨酸)含量及植株根冠比显著上升,且在100μmol·L-1浓度处理时作用效果最明显;MDA(丙二醛)含量、叶片相对电导率显著下降。综上可知,在低温迫下施加外源褪黑素可以提高大豆V1期光合速率、增加抗氧化酶活性,减轻膜脂过氧化反应并调节渗透物质含量,从而有助于缓解胁迫伤害,提高大豆幼苗耐冷能力。

Melatonin reduces acute lung injury in endotoxemic rats

Background Treatment with melatonin significantly reduces lung injury induced by bleomycin, paraquat and ischemia reperfusion. In the present study, we investigated the possible protective roles of melatonin in pulmonary inflammation and lung injury during acute endotoxemia. Methods Thirty-two male Sprague-Dawley rats were randomly assigned to four groups： vehicle ＋ saline group, melatonin ＋ saline group, vehicle ＋ lipopolysaccharide group, melatonin ＋ lipopolysaccharide group. The rats were treated with melatonin （10 mg/kg, intraperitoneal injection （i.p.）） or vehicle （1% ethanol saline）, 30 minutes prior to lipopolysaccharide administration （6 mg/kg, intravenous injection）. Four hours after lipopolysaccharide injection, samples of pulmonary tissue were collected. Blood gas analysis was carried out. Optical microscopy was performed to examine pathological changes in lungs and lung injury score was assessed. Wet/dry ratios （W/D）, myeloperoxidase activity, malondialdehyde concentrations and tumor necrosis factor-alpha （TNF-α） and interleukin-10 （IL-10） levels in lungs were measured. The pulmonary expression of nuclear factor-kappa B （NF-κB） p65 was evaluated by Western blotting. Results PaO2 in the vehicle ＋ lipopolysaccharide group decreased compared with that in the vehicle ＋ saline group. This decrease was significantly reduced in the melatonin ＋ lipopolysaccharide group. The lung tissues from the saline ＋ lipopolysaccharide group were significantly damaged, which were less pronounced in the melatonin ＋ lipopolysaccharide group. The W/D ratio increased significantly in the vehicle ＋ lipopolysaccharide group （6.1±0.18） as compared with that in the vehicle ＋ saline group （3.61±0.3） （P 〈0.01）, which was significantly reduced in the melatonin ＋ lipopolysaccharide group （4.8±0.25） （P 〈0.01）. Myeloperoxidase activity and malondialdehyde levels increased significantly in the vehicle ＋ lipopolysaccharide group compared with that in the vehicle ＋ saline group, which was reduced in the melatonin ＋ lipopolysaccharide group. The TNF-a level of pulmonary tissue increased significantly in the vehicle ＋ lipopolysaccharide group （（8.7±0.91） pg/mg protein） compared with that in the vehicle ＋ saline group （（4.3±0.62） pg/mg protein, P 〈0.01）. However, the increase of TNF-a level of pulmonary tissue was significantly reduced in the melatonin ＋ lipopolysaccharide group （（5.9±0.56） pg/mg protein, P 〈0.01）. Pulmonary IL-10 levels were elevated markedly in the vehicle ＋ lipopolysaccharide group in contrast to that in the vehicle ＋ saline group, whereas the elevation was augmented in the melatonin ＋ lipopolysaccharide group. The nuclear localization of p65 increased markedly in the vehicle ＋ lipopolysaccharide group and this enhancement of nuclear p65 expression was much less in the melatonin ＋ lipopolysaccharide group. Conclusion Melatonin reduces acute lung injury in endotoxemic rats by attenuating pulmonary inflammation and inhibiting NF-κB activation.