Title : The effect of Cr(III) supplementation combined with diversified Zn content in the diet on the iron status in Wistar rats
Abstract:
Zinc dyshomeostasis is a common phenomenon that is observed in individuals, especially in diabetic patients. Trace elements like Cr(III) Zn and Fe regulate the body’s insulin sensitivity and play an important role in maintaining blood glucose homeostasis, lipid metabolism, oxidative stress, and inflammatory response through multiple mechanisms. Chromium(III), zinc and iron may inhibit each other's absorption and transport to the tissues and affect excretion. Therefore, the interaction between Cr(III) and Zn may have a significant impact on the iron saturation status. This can lead to iron metabolism disorders, such as iron deficiency and anemia etc.
The aim of the study was to investigate the effect of chromium(III) supplementation in combination with diversified Zn content in the diet on the tissular Fe levels in healthy Wistar rats (female and male). The model studies were carried out on 69 (36♀ + 33♂) Wistar rats, which were randomly assigned to 6 experimental groups (6 females and 5-6 males) and then fed the test diets ad libitum for 6 weeks.
The control groups (C) were fed a semi-synthetic AIN-93 diet containing the recommended levels of Zn (35 mg/kg) and Cr(III) (1 mg/kg) for rodents. The other groups received AIN-93 diets modified for Zn(II) content (D - Zn deficiency - 5% RDA, OS - Zn oversupply - 500% RDA). At the same time, the diets were supplemented with Cr(III) at doses of 1 and 50 mg/kg. The sources of Zn and Cr(III) in the diets were Zn(II) carbonate and Cr(III) propionate (Cr3), an organic complex of Cr(III) with propionic acid (CrProp), respectively. The study adhered to strict ethical standards for animal research and was approved by the Local Ethical Committee in Poznań, Poland. The Fe content of the collected organ samples (liver, kidney, spleen, heart) and tissues (bone) was determined by atomic absorption spectrometry (AAS) after their prior mineralization with 65% nitric acid (V). Serum Fe concentration was determined by the colorimetric method using commercial kits (Roche Diagnostics, Germany). It was found that both dietary Zn deficiency and excess increased liver Fe content in females. However, as dietary Zn levels increased, a decrease in spleen Fe accumulation was observed in male rats.
Cr(III) supplementation independently did not change the Fe content in the liver, kidney, heart, and femur, except for the Fe serum concentration in females and Fe spleen content in male rats. Dietary Cr(III) supplementation at a dose of 50 mg/kg of diet decreased the serum Fe concentration in females and increased Fe splenic accumulation in male rats. A significant combined effect of the factors was also observed on the Fe content of the liver (female and male) and spleen (only male significant effect) of rats. The research demonstrated that the diversified Zn content in the diet, individually and in combination with Cr(III) supplementation affected the tissue distribution of iron in healthy rats.
