Long-term Consumption of Fermented Soybean-derived Chungkookjang Attenuates Hepatic Insulin Resistance in 90% Pancreatectomized Diabetic Rats

Abstract

Soy protein and isoflavonoids in soybeans exhibit the improvement of insulin resistance. Our previous IN VITRO study showed that Chungkookjang (CKJ), fermented unsalted soybeans, had better antidiabetic actions than cooked unfermented soybeans (CSB) by increasing isoflavones aglycones and small peptides. We investigated whether 40% fat diets with different protein sources such as CSB, CKJ, and casein modulated peripheral insulin resistance in 90% pancreatectomized (Px) diabetic rats. The Px rats weighing 209+/-14 g were freely provided casein, CSB, or CKJ diets for 8 weeks. Both CKJ and CSB increased whole body glucose disposal rates and glucose uptake into skeletal muscles of Px rats as much as rosiglitazone plus casein treated rats during euglycemic hyperinsulinemic clamp. In addition, CKJ and CSB decreased hepatic glucose output at hyperinsulinemic clamped states, compared to the Casein group. The reduction of hepatic glucose output was greater in CKJ than CSB. This reduction was associated with enhanced tyrosine phosphorylation of IRS2 and serine (473) phosphporylation of Akt, indicating improved hepatic insulin signaling. This improved signaling led to decreased phosphoenolpyruvate carboxykinase expression to reduce hepatic glucose output. In conclusion, fermented soybeans mainly with BACILLUS SUBTILIS improved hepatic insulin sensitivity better than unfermented soybeans by enhancing hepatic insulin signaling cascade in diabetic rats.

Herbal Therapies for Type 2 Diabetes Mellitus: Chemistry, Biology, and Potential Application of Selected Plants and Compounds

“…Soybean isoflavones have been reported to treat atherosclerosis, cancer, osteoporosis, and others [194]. In addition, soy protein and isoflavonoids in soybeans improve insulin resistance and enhancement of insulin release [195, 196]. Genistein is a key isoflavone present in soybean ( Glycine max ) and other edible plants and has been reported to have anticancer, antioxidant, anti-inflammatory, and antiosteoporosis activities.…”

Fermented Soypastes, Doenjang and Cheonggukjang, and Obesity

“…Cheonggukjang fermented with B. subtilis and B. amylofenices had no effect on body weight or adiposity [64], but Cheonggukjang fermented with B. lichemiformis reduced body fat [50]. Cheonggukjang fermented with B. lichemiformis was more effective in increasing insulin-stimulated glucose uptake in 3T3-L1 adipocytes and glucose-stimulated insulin secretion in insulinoma cell than that made with B. subtilis [64]. Yang et al [50] also observed that Cheonggukjang fermented with B. subtilis and B. amylofenices had less antidiabetic activity than Cheonggukjang fermented with B. lichemiformis.…”

“…In traditionally made Cheonggukjang, B. subtilis is the major microorganism, but B. amylofenices and B. lichemiformis may also be present. Cheonggukjang fermented with B. subtilis and B. amylofenices had no effect on body weight or adiposity [64], but Cheonggukjang fermented with B. lichemiformis reduced body fat [50]. Cheonggukjang fermented with B. lichemiformis was more effective in increasing insulin-stimulated glucose uptake in 3T3-L1 adipocytes and glucose-stimulated insulin secretion in insulinoma cell than that made with B. subtilis [64].…”

“…During fermentation, soybean glycosides are hydrolyzed by beta-glucosidase secreted by microorganisms, resulting in the formation of active aglycones and the promotion of intestinal absorption [11,12]. In addition, a diet containing 10% Cheonggukjang and meju had no effect on body weight but significantly reduced epididymal fat pads in pancreatectomized C57BL/6J mice [64] and Sprague-Dawley rats [50].…”

Fermented Soybean Products and Their Bioactive Compounds

“…Anti-diabetic effect was intensively studied with colleagues (D.J. Kwon et al, 2006Kwon et al, , 2007aKwon et al, , 2007b; several animal studies and a few human studies have evaluated the effects of fermented soybeans on glucose metabolism as reviewed previously . We found that chungkukjang improves glucose homeostasis by enhancing hepatic insulin sensitivity and insulinotropic actions in 90% pancreatectomized rats, a type 2 diabetic animal model (Kwon et al, 2007a(Kwon et al, , 2007b.…”