Renoprotective and blood pressure-lowering effect of dietary soy protein via protein kinase C beta II inhibition in a rat model of metabolic syndrome
Authors: Mambakkam Katchapeswaran Ravichandran
Carani Venkataraman Anuradha
Periyasamy Viswanathan
Nallasamy Palanisamy
Journal: Canadian Journal of Physiology and Pharmacology (2010)
Discipline: PHARMACOLOGY & TOXICOLOGY
Keywords: soy protein; casein; insulin sensitivity; blood pressure; PKCbetaII activation
Affiliations: Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalai Nagar, Tamil Nadu 608002, India., Department of Pathology, Faculty of Medicine, Rajah Muthaih Medical College, Annamalai University, Annamalai Nagar, Tamil Nadu 608002, India., Department of Statistics, Faculty of Science, Annamalai University, Annamalai Nagar, Tamil Nadu 608002, India.

Abstract:  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. 

Retracted: No

PubPeer comments:
 [Below] Fig 3 (C).  Representative immunoblots of PKCBetaII isoensyme in... **total lysate (C)**... 1. CCD; 2. FCD; 3. FSD; 4. CSD. [Above] Fig. 1. A from [Palanisamy et al (2011)] .  Representative immunoblots showing the expression of NF-u03baB p65 in kidney cytosol (a) and **nuclear fraction (b)**. ![file] The beta-actin loading control appears to be the same (after darkening and a vertical stretch). Could the authors clarify whether the blot was for nuclear fraction or total lysate? And whether the conditions involved fructose genistein combinations, or fructose soy protein? , 
 [Below] Fig 3 (B).  Representative immunoblots of PKCBetaII isoensyme in... membrane (B)... 1. CCD; 2. FCD; 3. FSD; 4. CSD. [Above] Fig. 2 from [Nallasamy Palanisamy Anuradha C. Venkataraman (2013)] .  Representative immunoblot of protein kinase C-bII (PKC-bII) isoenzyme in kidney (a) cytosol and **(b) membrane** ... Values are expressed as relative intensity and means of six independent experiments, and standard deviations represented by vertical bars. CON, control rats; FRU, fructose-fed rats; FRU u00fe GEN, fructose u00fe genistein (1 mg kg body weight per d); CON u00fe GEN, control u00fe genistein (1 mg kg body weight per d). ![file] The PKCbetaII bands display many features in common, despite differences in the conditions. , 
 It may be that the Acknowledgements would have benefited from adding a recognition that the Control-group and Frutose-Diet-Control-group components of the figures and tables had already appeared, in [Palanisamy et al (2008)] . ![file] I assume that the present soy-protein study and the earlier genistein study were conducted as a single experiment, thus using the same control groups. These results are consistently labeled, and I have no problem with them as such, but an acknowledgement of the re-use would avoid the appearance of double-dipping or salami-slicing. ![file] ,