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ARS Home » Southeast Area » Little Rock, Arkansas » Microbiome and Metabolism Research Unit » Research » Publications at this Location » Publication #218353
Title: Diets containing soy or rice protein isolate increase insulin sensitivity and improve lipid homeostasis in weanling rats fed high fat, high cholesterol Western diets as a result of activation of PPAR and LXR-mediated pathways

Author
item RONIS, MARTIN - ACNC/UAMS
item CHEN, YING - ACNC/UAMS
item BADEAUX, JAMIE - ACNC
item SHANKAR, KARTIK - ACNC/UAMS
item BADGER, THOMAS - ACNC/UAMS

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/29/2008
Publication Date: 4/5/2008
Citation: Ronis, M.J., Chen, Y., Badeaux, J., Shankar, K., Badger, T.M. 2008. Diets containing soy or rice protein isolate increase insulin sensitivity and improve lipid homeostasis in weanling rats fed high fat, high cholesterol Western diets as a result of activation of PPAR and LXR-mediated pathways [abstract]. The FASEB Journal. 22:892.2.

Interpretive Summary: The Arkansas Children's Nutrition Center has been studying the effects of proteins made from milk, rice and soy beans, because these are the major (in fact the only) proteins an infants eats during the first months of life. This report demonstrates that diets containing soy or rice protein isolate have significant health benefits. For example, insulin sensitivity is greater and the profile of fat in the circulation is healthier in weanling rats. These studies were conducted in young rats fed diets that resembled the typical diet that an American child would consume (high fat, high cholesterol). The study demonstrated that the mechanism by which these proteins work is through a series of proteins called PPAR and LXR.

Technical Abstract: The current study examined the effects of feeding soy protein isolate (SPI) and rice protein isolate (RPI) on insulin sensitivity and fat breakdown in weanling rats consuming high fat/high cholesterol diets. Male Sprague-Dawley rats were placed on semi-purified diets containing the milk protein casein (CAS) as the sole protein source on PND24 or onto CAS, SPI-, or RPI-based Western diets made with high fat and supplemented with 0.5% cholesterol. Prior to sacrifice at age 50 days, an oral glucose tolerance test was performed. High fat/high cholesterol feeding impaired glucose disposal (p < 0.05), suggesting insulin resistance. This was prevented by feeding SPI- or RPI-containing diets (p < 0.05). Increased serum and liver fat and cholesterol levels occurred with high fat/cholesterol feeding. Both SPI and RPI reduced serum and liver cholesterol (p < 0.05) and liver fat levels (p < 0.05). Expression of liver genes regulated by several transcription factors (PPAR'-, PPAR'- and LXR') were increased (p < 0.05) by feeding SPI- and RPI-containing diets relative to those in CAS-fed rats, as determined by real time RT--PCR. This was accompanied by increased binding of the transcription factors to their response elements on the acyl Co-A oxidase, glucokinase, and CYP7A1 gene promoters as measured in EMSA and ChIP assays. Increased expression mRNA and protein encoding then transcription factors themselves was also observed (p < 0.05). These data suggest that SPI and RPI increase insulin sensitivity via increased PPAR' signaling, and improved fat and cholesterol regulation as a result of signaling via PPAR' and LXR.