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ARS Home » Southeast Area » Little Rock, Arkansas » Arkansas Children's Nutrition Center » Research » Publications at this Location » Publication #148825
Title: EFFECTS OF WEANING TO DIETS CONTAINING RICE PROTEIN ISOLATE (RPI) ON GROWTH, PLASMA IGF1 AND EXPRESSION OF CYP2C11 AND CYP4A1 IN RAT LIVER

Author
item RONIS, MARTIN - ACNC
item REEVES, MISTY - ACNC
item HARDY, HOLLY - ACNC
item BADEAUX, JAMIE - ACNC
item DAHL, CHRIS - ACNC
item HARRISON, DAVID - ACNC
item HALEY, RANI - ACNC
item HUMPHREY, LANDON - ACNC
item FERGUSON, MATT - ACNC
item BADGER, THOMAS - UAMS

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2003
Publication Date: 6/30/2003
Citation: RONIS, M.J., REEVES, M., HARDY, H., BADEAUX, J., DAHL, C., HARRISON, D., HALEY, R., HUMPHREY, L., FERGUSON, M., BADGER, T.M. EFFECTS OF WEANING TO DIETS CONTAINING RICE PROTEIN ISOLATE (RPI) ON GROWTH, PLASMA IGF1 AND EXPRESSION OF CYP2C11 AND CYP4A1 IN RAT LIVER. Chemicke Listy. 2003. v. 97. p. S109. Abstract No. MP61.

Interpretive Summary: Rice contains a number of phytochemicals bound to its protein including vitamin E derivatives, tocotrienols and oryzanols, each of which have been suggested to contribute to health beneficial effects of rice consumption including reductions in cholesterol. In addition, protein isolates from rice are in widespread use in the food industry and have been shown to produce dietary protection against chemical-induced breast cancer in rats. We fed groups of pregnant female Sprague-Dawley rats semi-purifed diets with casein as the sole protein source during pregnancy and lactation. Their offspring were weaned at age 21 days to diets containing either casein (CAS) or rice protein isolate (RPI) as the sole protein source until sacrifice at age 34 days. All rats grew well through the study, but rats fed RPI diets had lower body weight gains and reduced plasma insulin-like growth factor (IGF-1). Since IGF-1 is regulated by growth hormone (GH), RPI may regulate the GH system. Male and female rats have different patterns of GH production, and the pattern of GH is important in regulating a protein called CYP2C11. CYP2C11 was found to be lower in RPI-fed rats, while another protein, CYP4A1 was increased. These results suggest that rice proteins and/or their phytochemicals can regulate important hormones and proteins that may be serve significant roles in disease prevention. Future studies will explore these effects and will determine the factors in rice responsible and the mechanisms underlying these effects.

Technical Abstract: Rice contains a number of phytochemicals including vitamin E derivatives, tocotrienols and oryzanols which have been suggested to contribute to health beneficial effects of rice consumption including reductions in cholesterol (1,2). In addition, protein isolates from rice are in widespread use in the food industry; have been shown to produce dietary protection against DMBA-induced mammary tumorigenesis in rats (3,4); and have many associated phytochemical constituents (5). We fed groups of time-impregnated female Sprague-Dawley rats pelleted AIN-93G diets with casein as the sole protein source ad libitum from gestational day 4 until their pups weaned at post-natal day 21. Litters were culled to 5 male and 5 female pups and N = 8-10 male or female pups were weaned onto amino acid matched pelleted diets, containing either casein (CAS) or rice protein isolate (RPI) as the sole protein source, ad libitum beginning on post-natal day 15 until sacrifice at post-natal day 34. Body weight gains were measured and serum IGF1 concentrations were assessed by radioimmunoassay. In addition liver microsomes were prepared. Testosterone 16'-hydroxylase was measured in male pups as an indicator of CYP2C11-dependent monooxygenase activity, CYP2C11 apoprotein was immunoquantified by Western blot and CYP2C11 mRNA was quantitated by real time RT-PCR. In addition, CYP4A1 apoprotein and mRNA were measured in liver microsomes from male and female pups by Western blot and real time PCR. Feeding RPI lower body weight gain in both male and female pups (p < 0.05). This was accompanied by reductions in plasma IGF1 concentrations (p < 0.05) indicating a suppression or delay in development of the GH/IGF1 axis in these animals. CYP2C11 mRNA and apoprotein expression and testosterone 16-alpha-hydroxylase were also inhibited in male pups (p < 0.05). Since food intake was not measured it is unclear if this effect was due to reduced intake, reduced dietary energy availability or a direct effect of RPI on GH secretion. CYP4A1 mRNA and apoprotein were increased 4-5-fold in pups of both sex suggesting a possible peroxisomal proliferator response to components of RPI.