| [BACKGROUND] Dietary restriction of calories (caloric restriction [CR]) increaseslongevity in phylogenetically diverse species. CR retards or prevents age-dependentdeterioration of tissues and an array of spontaneous and chemically induced diseasesassociated with obesity including cardiovascular disease, diabetes, and cancer. Anunderstanding of the molecular mechanisms that underlie the beneficial effects of CR willhelp identify novel dietary, pharmacological, and lifestyle strategies for slowing the rateof aging and preventing these diseases. Significant insights into aging can be achieved bystudying short-lived organisms, such as yeast, worms, and fruit flies. Many of themolecular pathways regulating aging in these lower organisms are conserved in mammalsand overlap with pathways regulating metabolism. For example, an insulin-growthhormone signaling system has been implicated in regulating aging and longevity in bothworms and mammals. Furthermore, the dysregulation of glucose homeostasis is ahallmark of aging in humans. In fact, type 2 diabetes can be conceptualized as a form ofaccelerated aging. Because aging and diabetes are intimately related at a molecular level,diabetes may be able to provide the link between disease treatment and the prevention ofage-related diseases. If specific molecular pathways controlling the rate of aging can bemodulated genetically, then perhaps they can be modulated pharmacologically. Becausedietary restriction can significantly decreased the serum insulin level and increased thehypersensitivity of insulin, we suppose that the expression of insulin signaling genes maybe related to the mechanism of dietary restriction.[Objectives]The purpose of our resrarch was to study the influence of dietary restrictionon the expression of insulin signaling pathway genes in mouse adipose tissue; to studythe influence of dietary restriction on the expression of glucose metabolism and insulinresistance related genes in mouse liver; and to analysis and discuss their molecularmechanism to dietary restriction.[Methods]①Replicating the animal model: Twenty four C57BL/6N male of 2 monthsage were subjected to either AL(Ad libitum) or DR(dietary restriction, 40% from AL)randomly about half and three months until sacrificed. The body mass,some mainorgans, blood glucose,and serum insulin were measured.②The 96 insulin signaling genesexpression were detected by Oligo Insulin Signaling Pathway Microarray (SuperArray),and two of the differentially expressed genes, Npy and Akt3 were validatedby Real Time PCR.③The 114 glucose metabolism related genes were detected by OligoGEArray Mouse Diabetes Microarray (SuperArray), and one of the differentiallyexpressed genes Akt2 was validated by Real Time PCR.④The protein of AKT2 in liverand AKT3 in the epididymis fat pads were determined by Western blotting.⑤Thequantity of phospho-Akt (Ser473) and phospho-Akt (Thr308) in liver and the epididymis fatpads were determined by KCTM Akt Pathway Activation ELISA Kit.[Results]①The body mass of group DR were decreased significantly compared to groupAL in 30 days (15.85±1.32 vs 19.05±2.06, n=12, p＜0.05); The main organ weigh, suchas liver, heart, kidney, pancreas and epididymis fat pad also decreased significantlybetween group DR and group AL(68.2 %, 43.6 %, 71.1%, 42.4 %, 39.8 % respectively);The blood serum insulin decreased markly after dietary restrition,the drop of bloodglucose was not obvious.②31 (20 up, 11 down regulation) of 96 insulin signalingpathway genes in epididymis fat pad were differentially expressed over 2 folds.③22 (20up, 2 down regulation) of 114 glucose metabolism related genes were differentiallyexpressed over 2 folds.④The expression of AKT2 protein in liver was increasedsignificantly (1.748±0.143 vs 1.025±0.093, n=4, P＜0.05); The content of AKT3 proteinin epididymis fat pad was increased significantly(1.03±0.095 vs 0.72±0.07, n=4, P＜0.05)also by Dietary restriction.⑤The phosphalation of Thr308 was not affected by DR inepididymis fat pad (1.05±0.1 vs 0.95±0.08, n=6)and in liver (1.13±0.07 vs 1.06±0.09,n=6), however, The phosphalation of AKTSer473 was increased significantly inepididymis fat pad (1.12±0.14 vs 1.51±0.1, n=6,P＜0.05) and in liver (1.17±0.069 vs1.54±0.12, n=6,P＜0.05).[Conclusion]①The establishment of DR mode is successful.②DR could affected theexpression of many insulin signaling pathway gene far beyond the number reported inrecent years.③The fat mass, represented by epididymis fat pad which may be thecause of insulin resistance, was decreased drastically.④DR could also affect the geneexpression related to glucose metabolism or insulin resistance.⑤The AKT familymember may play an very importment role on ditary restriction because its transcription,translation and phosphation were markly changed.
|
PDF Full Text Request