| With the improvement of human life expectancy,the incidence of brain diseases has gradually increased,higher than any other diseases,which makes it very important for brain research.Lipids account for about 50%of the dry weight in the brain,and play an important role in the formation of cell membrane,signal transmission,endocytosis and exocytosis,oxidative stress,cell apoptosis,inflammatory response and other aspects.Changes in lipids are associated with neurological diseases,including brain injury and neurodegenerative diseases.Therefore,it is very important to study the lipid molecules in the brain.There are various lipids in the brain,and it's a huge project to study lipids comprehensively.However,large groups of lipids,such as phospholipids and glycerides,have structural sites for binding fatty acids,that is,the abundance of fatty acids affects the abundance of these lipids.Therefore,the research of fatty acids is very important.There are many studies of fatty acids in the brain.But,in general,fatty acids studied in those researches are with relatively high concentration,such as four acid arachidonic acid docosahexaenoic acid and etc.These high concentration fatty acids are important,but fatty acids with low concentration,which is the majority of the fatty acids,are also important.In this paper,the method of stable isotope labeling was used to improve the response of low content fatty acids and reduce interference.The lipidomic comes from the need of study lipids in beings.There are many research methods applied in lipidomics.In this paper,liquid chromatography-mass spectrometry was used to analyze free fatty acids(FFA)in the brain.The research contents include the following two aspects:1.Explore how free fatty acids are distributed in different brain regions:The rat brain was divided into 12 different brain regions and the medulla oblongata were used.With equally light-labeled and heavy-labeled fatty acids,free fatty acids were detected with ultra-performance liquid chromatography-high resolution mass spectrometry.Using this strategy,a total of 1008 FFA candidates were discovered in rat brain and 181 FFA in every regions.Of those,56 fatty acids were positively identified and out of 56 were found to be common free fatty acids present in every brain region.In addition,quantitatively exploration was done for the distribution of fatty acids in the OB,OC,HP,and CE.Six fatty acids were found to be significantly different.These differences may relate to the different function of different brain regions.2.Analysis of fatty acids in brain of kainic acid epileptic rat model:Adolescent rats were intraperitoneally injected with saline solution of kainic acid.After 48 hours,the hippocampus was separated and labeled with DMED.UPLC-MS analysis was carried out on the basis of qualitative results in Part I and quantitative analysis was conducted.Four fatty acids were found to be significantly different,which includes arachidonic acid.With same model rats,the downstream metabolites of the different arachidonic acid in the hippocampus were analyzed.HP,TC and CE were chosen as martials.Samples were light labeled with heavy labeled standards and were analyzed with UPLC-MS/MS.5-?9-?15-?16-?19-HETE?8,9-?11,12-?14,15-EET and 14,15-DHET significantly decreased in HP.14,15-DHET?11-?19-?20-HETE in TC were changed,in which,11-HETE increased and others decreased.No significantly changes were found in CE.These changed fatty acids may relate to seizure. |
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