Content of essential and toxic trace elements in organs of obese Wistar and Zucker leprfa rats receiving quercetin

Abstract

Background: The levels of a number of essential and toxic trace elements in organs and tissues are affected by the disruptions in body homeostasis caused by obesity. Some of these elements may also be influenced by the consumption of biologically active substances of polyphenolic origin, which possess potent abilities to complex with transition metal ions.

Aims: The aim of this study was to determine the content of essential and toxic trace elements in Wistar outbred and hereditary obese Zucker Lepr^fa (Z) rats consuming a standard balanced diet or hypercaloric diet with excess fat and fructose, supplemented with quercetin or not supplemented.

Materials and methods: Male Wistar and Z rats were fed a control AIN-93M-based semi-synthetic diet or a high-fat-high-carbohydrate diet (HFCD, with 30% fat by weight and 20% fructose provided in the drinking water). A portion of the animals in each line and diet group was administered quercetin at 50 mg/kg body weight. Essential trace elements were included in the diets as a high-purity salt mixture. After the termination of feeding on day 63, the livers, kidneys, and brains of the rats were excised and the content of 16 elements (Fe, Mg, Cu, Mn, Co, Se, Zn, Cr, Ni, Al, Cd, As, Pb, V, Cs, and Ag) was measured by inductively coupled plasma mass spectrometry (ICP-MS).

Results: In the livers of the Z rats, the contents of Co, Zn, Mg, Fe, Se, and V were reduced and the content of Cr was increased compared to that of the Wistar rats. Supplementation with quercetin significantly decreased liver Fe, V, and Se content, which was more noticeable in the Wistar rats than in the Z rats. In kidneys of Z rats consuming control diet, the contents of Co, Cu, and Cs were decreased whereas those of Ni, Al, and Se were increased compared with the contents in the Wistar rats. The same trend was observed with HFCD feeding except for Cs content. Quercetin reduced kidney V content in both rat lines fed both diets, whereas it reduced Se and Cs only in the Z rats fed control diet. In the brains of the Z rats, a large increase was observed in some trace elements including Pb, Cd, Al, Cr, Ni, Fe, and V compared with the levels in the Wistar rat brains. Supplementation of the control diet with quercetin decreased Al and Ni in the brains of the Z rats.

Conclusion: There were significant differences in the mineral content of organs between the Wistar and Z rats, with different propensities for obesity. Moreover some of these effects had no straightforward association with decreased feed consumption or hepatic fat accumulation. When introduced into the diets, quercetin affected the content of essential and toxic elements, but with ambiguous physiological significance. Thus, indicators of essential and toxic trace elements deserve to be used in the protocols of preclinical as well as clinical trials of biologically active substances and food supplements.

Keywords: Zucker rats; obesity; organs; quercetin; rats; trace elements.