The use of n-3 fatty acids (n-3 FA) from fish oil as dietary supplements to protect against inflammatory disorders is recently on the rise by the general public in US. Further, 40% calorie restriction (CR) is also known to prolong lifespan of rodents by decreasing the expression of various pro-inflammatory genes, cytokines and insulin resistance. We recently reported that combination of n-3 FA + CR significantly extend lifespan of autoimmune-disease prone mice when compared to mice fed n-3 FA ad-libitum (AL) or mice fed corn oil (n-6 FA) with CR. We hypothesize that n-3 FA+CR increases activity of antioxidant enzymes and decreases pro-inflammatory cytokines leading to increased lifespan. We now further hypothesize that a similar mechanism may operate in prolonging significantly the lifespan of long-lived C57BL/6 (B6) mice when fed a diet with n-3 FA+CR than when fed n-6 FA+CR. In addition, n-3 FA may also decrease insulin resistance and age-related bone loss. Based on strong preliminary data, we propose to undertake new studies by feeding concentrated n-3 FA as well as by including transgenic mice carrying the fat-1 gene which endogenously synthesizes n-3 fatty acids and lowers pro-inflammatory n-6 FA in all tissues. We will use both B6 mice fed n-3 FA, AL or CR and fat-1+ x B6 mice fed AL or CR and compare with mice fed n-6 FA, AL or CR to further establish the protection induced by exogenous or endogenous n-3 fatty acids with and without CR on mean and maximal lifespan.
The specific aims are:
Aim 1 : Effect of feeding n-3 fatty acids, AL or CR (40%), from 4 mo and 20% CR 15 mo onwards to measure changes in the survival of B6 mice and to compare with fat-1+ x B6 F1 and fat-1- x B6 F1 mice fed AL or CR (40%).
Aim 2 : Measure changes in anti- and pro- inflammatory cytokines and expression of longevity SIRT I gene with age.
Aim 3 : Measure changes in fat and lean body mass as well as adipokines and bone mineral density during aging with or without n-3 FA or fat-1 gene in AL and CR. Since n-3 FA are found to be anti-inflammatory, the proposed studies are likely to establish the protective role of n-3 FA + CR in down-regulating oxidative stress and inflammatory gene expression thereby prolonging lifespan, much longer than n-6 FA + CR fed mice. In summary, favorable outcome of this study is likely to reinforce the intake of n-3 FA with CR to induce several health benefits in elderly, particularly against inflammation and musculoskeletal loss during aging.
This grant proposal is directed closely to study the effect of commonly consumed n-6 (corn oil) fatty acids vs. n-3 (fish oil) fatty acids containing diets fed to mice ad-libitum and 40% or 20% calorie restriction to measure optimal lifespan, anti-inflammatory cytokines and bone mass, in long-lived C57BL/6 and fat-1 tg mice.
