Renal Effects of Oral Maillard Reaction Product Load in the Form of Bread Crusts in Healthy and Subtotally Nephrectomized Rats

Abstract

The biological consequences of chronic consumption of Maillard reaction products (MRPs) on renal function in health and renal disease are still incompletely understood. We investigated the metabolic and renal effects of a diet with varying MRP content in healthy and subtotally nephrectomized rats. Male Wistar rats were subjected to sham operation (control, C, n = 12), or to 5/6 nephrectomy (5/6NX, n = 12). Both groups were randomized into subgroups and pair-fed with either a MRP-poor or -rich diet for six weeks. The diet was prepared by replacing 5% or 25% of wheat starch by bread crust (BC). In spite of pair-feeding, the rats on the 25% BC diet gained more body weight (C: 183 +/- 6 g; C + 5% BC: 197 +/- 7 g; C + 25% BC: 229 +/- 6 g [P < 0.05]; 5/6NX: 165 +/- 10 g; 5/6NX + 5% BC: 202 +/- 3 g; 5/6NX + 25% BC: 209 +/- 8 g [P < 0.05]) and had a higher organ weight (heart, liver, lung, kidney/remnant kidney). Bread crust-enriched diet induced proteinuria (C: 15 +/- 5 mg/24 h; C + 5% BC: 19 +/- 4; C + 25% BC: 26 +/- 3 [P < 0.05]; 5/6NX: 30 +/- 7 mg/24 h; 5/6NX + 5% BC: 47 +/- 9; 5/6NX + 25% BC: 87 +/- 19 [P < 0.01]) and a rise in urinary transforming growth factor beta(1) excretion (C: 0.4 +/- 0.1 ng/24 h; C + 5% BC: 0.6 +/- 0.1; C + 25% BC: 1.2 +/- 0.3; 5/6NX: 0.5 +/- 0.1 ng/24 h; 5/6NX + 5% BC: 0.9 +/- 0.1; 5/6NX + 25% BC: 1.6 +/- 0.2 [P < 0.01]). Plasma creatinine or creatinine clearance were not affected significantly. In conclusion, our data suggests that long-term consumption of a diet rich in MRPs may lead to damage of the kidneys.

Genetic variability in the RAGE gene: Possible implications for nutrigenetics, nutrigenomics, and understanding the susceptibility to diabetic complications

“…In spite of the fact that the metabolic transit data for the majority of ingested AGEs remain unknown, several lines of evidence suggest that an AGE-rich diet can lead, at least in susceptible individuals (such as infants, elderly and diseased people), to potentially pathologic consequencesbody and organ weight gain, obesity with metabolic syndrome [79, 84 -86], renal damage (via induction of proteinuria and/or enhanced formation of pro-fibrotic transforming growth factor b 1 (TGF-b 1 )) [79,84,85,87], accelerated atherosclerosis (via lipid peroxidation) [73,84], and lowdegree inflammation [74,88].…”

An Advanced Glycation End Product (AGE)-Receptor for AGEs (RAGE) Axis Restores Adipogenic Potential of Senescent Preadipocytes through Modulation of p53 Protein Function

“…Recent studies showed that chronic AGE-rich standard diet feeding studies in animals showed an increase in body weight with no report on the change in adipose mass with elevated insulin resistance (14,64,65). Conversely, a long term of feeding study of mice with AGE-restricted standard diet resulted in reduced body weight gain with enhanced insulin sensitivity and life span at the end of the study (66).…”

“…Supporting this notion, a recent study demonstrated that mice fed a standard chow diet supplemented with 1 mg of MG-BSA/g of diet for 18 months showed elevated AGE levels in the serum as well as in adipose tissue to 0.43 mg of CML-BSA/ml and 190 nmol of MG/g of tissue, respectively (63). Collectively, these studies suggest that the AGE concentration we used in our study is likely to be achievable in the sera of humans and animals after a chronic oral administration of an AGE-rich diet.Recent studies showed that chronic AGE-rich standard diet feeding studies in animals showed an increase in body weight with no report on the change in adipose mass with elevated insulin resistance (14,64,65). Conversely, a long term of feeding study of mice with AGE-restricted standard diet resulted in reduced body weight gain with enhanced insulin sensitivity and life span at the end of the study (66).…”

Maillard-Reaktionsprodukte in Lebensmitteln: Mögliche gesundheitliche Bedeutung

“…In der finalen Phase werden weitere heterocyclische Verbindungen gebildet und durch Polymerisation und Vernetzung ("crosslinking") dieser Verbindungen entstehen die niedermolekularen Prämelanoidine und die höhermolekularen Melanoidine (Krause, 2005;Somoza, 2005). Prämelanoidine und Melanoidine werden auch zusammenfassend als "fortgeschrittene Glykierungsprodukte" oder englisch als "Advanced Glycation Endproducts (AGEs)" bezeichnet (Bierhaus, 2004).…”

“…Die Bildungsmechanismen, die zur Entstehung der Vorstufen der Melanoidine führen, sind schon recht gut bekannt, aber über die nieder-und hochmolekularen Produkte der späteren Stadien der Maillard-Reaktion existieren bisher nur wenige Kenntnisse (Somoza, 2005). Die Struktur und die funktionellen Eigenschaften von Melanoidinen sind Gegenstand zahlreicher Forschungstätigkeiten (Krause, 2005).…”