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The Effect of Feeding Soy Protein Isolate and/or Omega‐3 Polyunsaturated Fatty Acids on the Spleen of Female PCK Rats
Author(s) -
Gibson Lauren B.,
Maditz Kaitlin,
Benedito Vagner A,
Tou Janet C
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.915.35
Subject(s) - casein , soy protein , lipogenesis , spleen , soybean oil , oleic acid , stearic acid , fatty acid , fatty liver , palmitic acid , medicine , biology , polyunsaturated fatty acid , endocrinology , food science , chemistry , lipid metabolism , biochemistry , disease , organic chemistry
Few studies have investigated the effect of diet on the spleen. Studies have suggested that spleen lipid metabolism may play a role in non‐alcoholic fatty liver disease (NAFLD). Upregulated de novo lipogenesis (DNL) in the liver can cause NAFLD that can progress to cirrhosis and liver failure. This has important implications with NAFLD being the leading cause of chronic liver disease in adults and children consuming Westernized diets. The objective of this study was to determine the effect of diet on splenic DNL and inflammatory response. Female PCK rats aged 28 days were randomly assigned to one of four purified diets (n=12/group) and fed for 12 weeks. Diet groups consisted of 1) Casein + Corn Oil (Casein + CO), 2) Casein + Soybean Oil (Casein + SO), 3) Soy protein Isolate + Soybean Oil (SPI + SO), or 4) Soy protein Isolate + a 1:1 soybean: salmon oil blend (SPI + SB). Previously, we found NAFLD to be highest (P=0.003) in the SPI+SB group. In this study, the SPI+SB group showed a trend of high splenic weight (P=0.10). Spleen length was longer (P=0.02) in the SPI+SB fed group compared to the Casein + CO and Casein + SO groups. Splenic fatty acid profiles were determined by gas chromatography. Splenic content of saturated fatty acids (palmitic acid (C16:0) and stearic acid (C18:0)) and monounsaturated fatty acids (palmitoleic acid (C16:1n‐7) and oleic acid (C18:1n‐9)) were not significantly different between diet groups. Gene expression by real time quantitative polymerase chain reaction (RT‐qPCR) determined no significant difference in expression of transcription factors regulating DNL in the spleen including carbohydrate‐responsive element binding protein (ChREBP) and sterol regulatory element binding protein 1 (SREBP‐1c). The expression of transcription factor peroxisome proliferator‐activated receptor alpha (PPAR‐a) gene was used as a marker of splenic lipolysis, but showed no significant differences among diet groups. Rats fed the SPI+SB diet containing the highest (P<0.001) dietary eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA) exhibited the highest (P<0.001) splenic EPA and DHA, and the lowest (P=0.03) splenic content of AA. However, no significant differences in the expression of genes involved in regulating inflammation (tumor necrosis factor alpha (TNF‐a), interleukin‐6 (IL‐6), and interleukin 10 (IL‐10)) existed between diet groups. Based on these results, the diet treatments had no significant effect on splenic lipid metabolism or inflammatory function in PCK rats with NAFLD. Support or Funding Information This project was supported by the United Soybean Board Soybean Health Incentive Grant, West Virginia University PSCoR 10008736.6‐11‐NT10055R, West Virginia University Agriculture and Forestry Experimental Station Hatch Grant WVAA00665, and West Virginia University summer undergraduate education program.