Rufino-Palomares Eva E, Reyes-Zurita Fernando J, García-Salguero Leticia, Peragón Juan, de la Higuera Manuel, Lupiáñez José A
Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Granada, Spain.
Department of Biochemistry and Molecular Biology I, Faculty of Sciences, University of Granada, Granada, Spain.
Comp Biochem Physiol C Toxicol Pharmacol. 2016 Sep;187:32-42. doi: 10.1016/j.cbpc.2016.05.002. Epub 2016 May 10.
NADPH plays a central role in reductive biosynthesis of membrane lipids, maintenance of cell integrity, protein synthesis and redox balance maintenance. Hence, NADPH is involved in the growth and proliferation processes. In addition, it has been shown that changes in nutritional conditions produced changes in NADPH levels and growth rate. Maslinic acid (MA), a pentacyclic triterpene of natural origin, is able to stimulate NADPH production, through regulation of the two oxidative phase dehydrogenases of the pentose phosphate pathway. Our main objective was to study the effects of MA on the kinetic behaviour and on the molecular expression of two NADPH-generating systems, NADP-dependent isocitrate dehydrogenase (NADP-IDH) and malic enzyme (ME), in the liver and white muscle of gilthead sea bream (Sparus aurata). Four groups of 12g of a mean body mass were fed for 210days in a fish farm, with diets containing 0 (control), and 0.1g of MA per kg of diet. Two groups were fed ad libitum (C-AL and MA-AL) and another's two, with restricted diet of 1% of fish weight (C-R and MA-R). Results showed that MA significantly increased the main kinetic parameter of the NADPH-forming enzymes (NADP-IDH and ME). In this sense, specific activity, maximum velocity, catalytic efficiency and activity ratio values were higher in MA conditions than control groups. Moreover, these changes were observed in both feeding regimen, AL and R. Meanwhile, the Michaelis constant changed mainly in groups fed with the MA and restricted diet, these changes are related to the best substrate affinity by enzyme. Moreover, in the Western-blot result, we found that MA increased both protein levels studied, this behaviour being consistent with the regulation of the number of enzyme molecules. All results, indicate that MA, independently of the fed regimen, could potentially be a nutritional additive for fish as it improved the metabolic state of fish, as consequence of increased activity and expression of NADP-IDH and ME enzymes.
烟酰胺腺嘌呤二核苷酸磷酸（NADPH）在膜脂的还原性生物合成、细胞完整性的维持、蛋白质合成以及氧化还原平衡的维持中发挥着核心作用。因此，NADPH参与生长和增殖过程。此外，研究表明营养条件的变化会导致NADPH水平和生长速率的改变。齐墩果酸（MA）是一种天然来源的五环三萜，能够通过调节磷酸戊糖途径的两种氧化相脱氢酶来刺激NADPH的产生。我们的主要目的是研究MA对金头鲷（Sparus aurata）肝脏和白色肌肉中两个NADPH生成系统，即依赖烟酰胺腺嘌呤二核苷酸磷酸（NADP）的异柠檬酸脱氢酶（NADP-IDH）和苹果酸酶（ME）的动力学行为和分子表达的影响。将四组平均体重为12克的鱼在养鱼场中饲养210天，分别投喂含有0（对照组）和每千克饲料含0.1克MA的饲料。两组自由采食（C-AL和MA-AL），另外两组采用限制投喂，投喂量为鱼体重的1%（C-R和MA-R）。结果表明，MA显著提高了NADPH生成酶（NADP-IDH和ME）的主要动力学参数。从这个意义上说，MA处理组的比活性、最大速度、催化效率和活性比值均高于对照组。此外，在自由采食和限制投喂两种饲养方式下均观察到了这些变化。同时，米氏常数主要在投喂MA且限制投喂的组中发生变化，这些变化与酶对底物的最佳亲和力有关。此外，在蛋白质免疫印迹结果中，我们发现MA增加了所研究的两种蛋白质的水平，这种行为与酶分子数量调节一致。所有结果表明，无论饲养方式如何，MA都有可能成为鱼类的营养添加剂，因为它通过增加NADP-IDH和ME酶的活性和表达，改善了鱼的代谢状态。
