Studies On Nrf2and Antioxidantive Metabolism Affected By Rice Proteins

Rice protein is a good plant protein, which has higher nutritional value. Thsu, theantioxidative effect and mechanism exerted by rice protein has been focused on and theevidences for antioxidant funtion of rice protein have been provided in this study.To elucidate the mechanism exerted by rice protein, the effects of rice protein,riceprolamin and rice glutelin on antioxidative effect and Nrf2pathway were investigated ingrowing rats and adult rats fed by high-fat, cholesterol-free and–enriched diets, afters.The major conclusions have been drawn as below:(1) By oral admistration, rice proteins could reduce hepatic accumulation of MDAin growing rats, whereas the activities of SOD and GSH-Px could be increased by riceproteins as compared with casein. Results suggest that the antioxidative effects of riceproteins could be enhanced with increasing levels of rice protein.(2) By oral admistration, observations that rice prolamin and rice glutelin couldinhibit the accumulations of MDA and PCO and stimulate the activities of SOD andGSH-Px indicate that the antioxidative effect induced by rice prolamin is stronger thanthat of rice glutelin. These findings suggest that the composition is an important factorto regulate the antioxidative action of rice protein.(3) Under cholesterol-enriched and ad libitum experimental condition, rice proteincould increase the activity of SOD and decrease the hepatic levels of MDA and PCO ingrowing rats as compared to casein, suggesting rice protein could produce antioxidativeeffect when growing rats fed cholesterol-enriched diets.(4) Under high-fat and ad libitum experimental condition, rice protein couldincrease the activities of SOD and GSH-Px and decrease the hepatic levels of MDA andPCO in growing rats as compared with casein, suggesting rice protein could produceantioxidative effect when growing rats fed high-fat diets.(5) Without cholesterol in diets, compared with casein, rice protein could reducethe hepatic accumulations of MDA, PCO and GSSG, whereas the hepatic level of GSHcould be increased by rice protein. Accompanying with the increasing activities ofSOD,CAT, γ-GCS, GSH-Px,GST and GR, the Nrf2transport could be promted into thenuclear. The gene expressions of Nrf2and its related factors, i.e. GCLM, GCLC,GSH-Px, γ-GCS, GR, HO-1, GST and NQO1, could be stimulated in adult rats. Theprotein expressions of γ-GCS, HO-1, GST and NQO1have also been increased in adultrats fed cholesterol-free dietary condition, suggesting that the antioxidative effect of riceprotein in adult rats are attributed to the decrease of oxidative stress, the increase of antioxidative enzyme activity and the stimulation of Nrf2antioxidative pathway.(6) Under cholesterol-enriched dietary condition, compared with casein, riceprotein could reduce the hepatic accumulations of MDA, PCO and GSSG, whereas thehepatic level of GSH could be increased by rice protein. Accompanying with theincreasing activities of SOD,CAT, γ-GCS, GSH-Px,GST and GR, the Nrf2transportcould be promted into the nuclear. The gene expressions of Nrf2and its related factors,i.e. GCLM, GCLC, GSH-Px, γ-GCS, GR, HO-1, GST and NQO1, could be stimulatedin adult rats. The protein expressions of γ-GCS, HO-1, GST and NQO1have also beenincreased in adult rats fed cholesterol-enriched dietary condition, indicating that theantioxidative effect of rice protein on adult rats are attributed to the decrease ofoxidative stress, the increase of antioxidative enzyme activity and the stimulation ofNrf2antioxidative pathway. These findings suggest that dietary cholesterol play a minorrole involved with antioxidative action of rice protein.