Renoprotective and blood pressure-lowering effect of dietary soy protein via protein kinase C beta II inhibition in a rat model of metabolic syndrome.
We studied whether substitution of soy protein for casein can improve insulin sensitivity, lower blood pressure (BP), and inhibit protein kinase C betaII (PKCbetaII) activation in kidney in an acquired model of metabolic syndrome. Adult male rats were fed 4 different diets: (i) starch (60%) and casein (20%) (CCD), (ii) fructose (60%) and casein (20%) (FCD), (iii) fructose (60%) and soy protein (20%) (FSD), and (iv) starch (60%) and soy protein (20%) (CSD). Renal function parameters, BP, pressor mechanisms, PKCbetaII expression, oxidative stress, and renal histology were evaluated after 60 days. FCD rats displayed insulin resistance and significant changes in body weight, kidney weight, urine volume, plasma and urine electrolytes accompanied by significant changes in renal function parameters compared with CCD rats. Elevated BP, plasma angiotensin-converting enzyme (ACE) activity, renal oxidative stress, and reduced nitrite (NO) and kallikrein activity were observed. Western blot analysis revealed enhanced renal expression of membrane-associated PKCbetaII in the FCD group. Histology showed fatty infiltration and thickening of glomeruli while urinary protein profile revealed a 5-fold increase in albumin. Substitution of soy protein for casein improved insulin sensitivity, lowered BP and PKCbetaII activation and restored renal function. Antioxidant action, inhibitory effect on ACE and PKCbetaII activation, and increased availability of kinins and NO could be contributing mechanisms for the benefits of dietary soy protein.
Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar, Tamil Nadu 608002, India.
Nallasamy
N
Palanisamy
Periyasamy
P
Viswanathan
Mambakkam Katchapeswaran
MK
Ravichandran
Carani Venkataraman
CV
Anuradha
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004044:Dietary Proteins / Q000494:pharmacology / Q000627:therapeutic use; D004195:Disease Models, Animal; D006973:Hypertension / Q000178:diet therapy / Q000201:enzymology* / Q000503:physiopathology; D007674:Kidney Diseases / Q000178:diet therapy* / Q000201:enzymology / Q000517:prevention & control; D008297:Male; D024821:Metabolic Syndrome / Q000178:diet therapy* / Q000201:enzymology* / Q000503:physiopathology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000502:physiology; D064546:Protein Kinase C beta; D047428:Protein Kinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D030262:Soybean Proteins / Q000494:pharmacology / Q000627:therapeutic use*
D000959:Antihypertensive Agents; D004044:Dietary Proteins; D047428:Protein Kinase Inhibitors; D030262:Soybean Proteins; D011493:Protein Kinase C; D064546:Protein Kinase C beta