膳食n6/n3脂肪酸构成对脂联素表达的调节及CDK5/PPARγ介导的机制研究

Adiponectin has gained continuing attentions as a molecular target closely related to obesity and metabolic disease. Based on our former findings that different ratios of saturated/monounsaturated/polyunsaturated fatty acids(S/M/P)in diets play a role in the expression of adiponectin and its receptors, the present study is aimed to explore the regulation of varying dietary n-6/n-3 polyunsaturated fatty acid ratios on the expression of adiponectin and its receptors through in vitro cell culture experiments and animal experiments, find out the appropriate n-6/n-3 fatty acid ratio that promotes the expression of adiponectin and thereby contribute to the prevention and cure of obesity and metabolic disease. The molecular mechanism underlying the regulation of n-6/n-3 polyunsaturated fatty acid ratios on adiponectin, which is mediated by cyclin-dependent kinase 5 (CDK5) and peroxisome proliferators activator receptorγ(PPARγ), would also be discussed. Our findings will provide important new theoretical basis for ascertaining a reasonable dietary ratio of n-6/n-3 fatty acid，as well as novel thoughts and scientific evidence for the prevention and cure of obesity and metabolic disease.

脂联素是对肥胖及相关代谢性疾病防治极有价值的分子靶点，一直以来倍受关注。本项目在前期研究发现膳食饱和脂肪酸/单不饱和脂肪酸/多不饱和脂肪酸构成影响脂联素及其受体表达的基础之上，进一步通过体外细胞培养实验和动物实验研究膳食不同n-6/n-3多不饱和脂肪酸构成对脂联素及其受体表达的调节作用，探讨能提高脂联素表达水平，利于肥胖及相关代谢性疾病防治的适宜n-6/n-3多不饱和脂肪酸构成比，并探讨由CDK5/PPARγ介导的n-6/n-3多不饱和脂肪酸构成调节脂联素表达的分子机理。其研究结果将为确定膳食中n-6/n-3 多不饱和脂肪酸适宜比例提供新的重要的理论依据，为肥胖及相关代谢性疾病的预防和治疗提供新的思路和科学依据。

本项目通过动物实验和体外细胞培养实验，研究不同n-6/n-3多不饱和脂肪酸构成对脂联素表达的影响，探讨能上调脂联素表达，利于相关疾病防治的适宜n-6/n-3PUFA构成比，并探讨由CDK5/PPARγ介导的n-6、n-3PUFA调节脂联素表达的分子机理。.本研究发现：.1.在脂肪供能比为25%的情况下，不同n-6/n-3PUFA构成比对大鼠脂肪组织脂联素表达的调节作用不同，当n-6/n-3=5:1时，脂联素及PPARγ表达水平最高，且两者表达水平呈正相关；.2.在高脂膳食（脂肪供能比为40%）的情况下，各组大鼠体重、血脂、血糖等均高于对照组，脂联素表达水平则低于对照组，且n-6/n-3PUFA构成比越大脂联素表达水平越低。高脂膳食使大鼠脂肪组织CDK5和p-PPARγ蛋白表达水平升高，并随n-6/n-3PUFA构成比增大而增加；.3. n-6/n-3PUFAs构成影响3T3-L1脂肪细胞脂联素表达。在n-6/n-3PUFAs构成比为1:1和5:1时显著上调脂联素的表达，在30比1时则完全抑制脂联素的表达；.4. n-6、n-3PUFA对脂肪细胞脂联素表达有不同影响。n-3PUFA较n-6PUFAs更能促进脂联素的表达，n-3PUFAs（DHA、EPA、ɑ-ALA）中，DHA上调脂联素表达的作用最强。n-6PUFAs（AA、LA）中， LA的上调作用较强；.5. n-3PUFA可上调脂肪细胞PPARγ mRNA及蛋白表达， n-6PUFA则对PPARγ的表达无明显影响。GW9662可显著抑制n-3PUFA对PPARγ及脂联素表达的上调作用，提示n-3PUFA能够通过PPARγ促进脂联素的表达。n-6PUFA则可能对该通路无影响；.6. n-3、n-6PUFA可调节胞内CDK5活性，DHA、AA呈抑制效应，而EPA、α-ALA及LA呈促进效应。DHA及AA可减弱PPARγ 273位丝氨酸磷酸化，而EPA、α-ALA及LA的作用相反。TNF-α可阻遏DHA对PPARγ磷酸化的下调作用，roscovitine可阻遏EPA及α-ALA对PPARγ磷酸化的上调作用。以上提示CDK5/p-PPARγ可能是PUFA调节胞内脂联素表达的信号通路之一。.该研究为确定膳食中n-6/n-3 PUFA适宜构成比及肥胖相关代谢性疾病的防治提供了新的思路和科学依据，有重要理论价值和现实意义。