The Synergistic Effects Of Calories Restriction And Polyunsaturated Fatty Acids On Rats With Colitis

Objective:The experiment used factorial design was to observe the synergistic effects of calories restriction and polyunsaturated fatty acids on ulcerative colitis, and preliminary interpretation of PPARγ/NF-κB signaling pathway.Methods:Forty Sprague-Dawley female rats were divided into five groups randomly: control group, model group, calories restriction(CR)group, 5:1PUFAs plus ad libitum(5:1PUFAs plus AL)group, 5:1PUFAs plus calories restriction(5:1PUFAs plus CR)group. CR groups provided with a limited daily food allotment of 60% of that eaten by the ad libitum-fed.After 14 weeks, colitis was induced by administration of 5% dextran sulfate sodium for 7consecutive days. All rats were sacrificed 3 days later. Stripping out the colon, length was measured, weighed and calculated wet weight index, observed the general and evaluted the histological score. Biochemistry methods was to detected the activities of myeloperoxidase.The levels of IL-2, IL-6, IL-10 and TNF-α was measured by ELISA.Immunohistochemistry and RT-PCR was to detect the expression level of PPARγ, NF-κB p65 protein and m RNA respectively.Results:1. Body weight: After the experiment, compared with rats fed ad libitum, the calorie restriction rats weight was lighter, especially 5:1PUFAs plus CR group was lightest, the difference was statistic significantly(P<0.05).2. Model group showed mucosal congestion and swelling, colon surface erosion,bleeding and ulcers, and its macroscopic score was increased; Compared with model group,5:1PUFAs plus CR group alleviate the above features, score lower(P<0.05).3. Model group has higher DAI than the control group(P<0.05); Compared with model group, 5:1PUFAs plus CR group has lower score, the difference was statistic significantly(P<0.05).4. Compared with control group, model group was significantly shorter length of the colon, the weight increased significantly(P<0.05). Compared with the model group, colon length, weight and wet weight index of 5:1PUFAs plus CR group were decreased(P<0.05).5. Histopathology score: normal group showed colonic mucosa intact, epithelial cells arranged in neat rows, glands rules, no inflammatory cell infiltration, and no congestion,edema and ulceration; the model group colonic mucosal epithelium lost, glands malalignment, inflammatory cell infiltration. Compared with the model group, 5:1PUFAs plus CR group improved inflammation, and the score was statistic significantly(P<0.05).6. MPO activity of model group was highest and 5:1PUFAs plus CR group was lower,the difference was statistic significantly(P<0.05).7. With respect to the normal group, model group increased TNF-α, IL-6 levels and decraesed IL-2, IL-10 level, the difference was statistic significantly(P<0.05). Compared with the model group, 5:1PUFAs plus CR group decreased IL-6 and TNF-α levels,increased IL-2 and IL-10 levels(P<0.05).8. Compared to model group, the 5:1PUFAs plus CR group increased the expression of PPARγ m RNA and decrease NF-κB p65 m RNA(P<0.05). The relationship between calories restriction and 5:1PUFAs on PPARγ and NF-κB p65 m RNA is synergy.9.Compared with the normal group, the expression levels of NF-κB p65 m RNA was increasad, PPARγ m RNA expression decreased in the model group, the difference was statistic significantly(P<0.05); compared to model group, 5:1PUFAs plus calories restriction group can decreased NF-κB p65 m RNA expression and increased PPARγm RNA, the difference was statistic significantly(P<0.05).Conclusions:1.Dextran sulfate sodium(DSS)-induced colitis is a well established experimental model.2.5:1PUFAs combined with calories restriction can alleviated clinical symptoms of UC obviously, the possible mechanism is reduce oxidative damage and anti-inflammatory effects of calories restriction and polyunsaturated fatty acids which can adjust the release of cytokines. It also can increase the expression of PPARγ to down regulate NF-κBp65transduction, inhibit inflammatory cell recruitment, thereby reducing the expression of inflammatory factors, slowing inflammation.