Modulation of methylglyoxal and glutathione by soybean isoflavones in mild streptozotocin-induced diabetic rats.
OBJECTIVE
Evidence shows that methylglyoxal (MG), a very reactive metabolite of glucose, plays a critical role in the pathogenesis of diabetes and diabetic complications. Although soy isoflavones have beneficial effects in diabetes, the role of soy isoflavones in regulating MG levels is unknown. The present study investigates the effects of soy protein isoflavones on MG and reduced glutathione (GSH).


RESULTS
Mild diabetes was induced in male Sprague-Dawley rats by intraperitoneal injection of 35 mg/kg streptozotocin (STZ). The diabetic rats were then randomly divided into three groups and received a special diet supplemented with casein (control), low-isoflavone soy protein (LIS), or high-isoflavone soy protein (HIS) for eight weeks, respectively. Compared to the control or LIS group, HIS diet significantly increased serum insulin levels (p<0.01 or 0.05) and reduced serum glucose and MG levels (p<0.05). Serum GSH levels were increased in HIS-fed rats compared with the control or LIS group (p<0.01). Serum total cholesterol and homocysteine levels were significantly lower in HIS and LIS rats than those of the control rats.


CONCLUSIONS
Both LIS and HIS diets can lower serum lipid and homocysteine levels in this mild diabetic model. HIS diet enhances insulin secretion and reduces glucose level. Moreover, the HIS diet has potential in reducing MG and increasing GSH levels. In addition to its hypoglycemic effect, the antioxidant protection may provide beneficial effects in preventing the development of diabetic complications.
Lu
Mei-Ping
MP
Department of Pathology and Laboratory Medicine, College of Medicine, University of Saskatchewan, 103 Hospital Drive, Saskatoon, SK, Canada.
Wang
Rui
R
Song
Xiuyuan
X
Wang
Xiaoxia
X
Wu
Lingyun
L
Meng
Qing H
QH
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005978:Glutathione / Q000097:blood*; D006710:Homocysteine / Q000097:blood; D007328:Insulin / Q000097:blood; D007529:Isoflavones / Q000494:pharmacology*; D008297:Male; D011765:Pyruvaldehyde / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013025:Glycine max; D013311:Streptozocin
D001786:Blood Glucose; D007328:Insulin; D007529:Isoflavones; D006710:Homocysteine; D013311:Streptozocin; D011765:Pyruvaldehyde; D005978:Glutathione