[The changes of copper metabolism in rats fed with low- or high-calorie ration]

Copper is an essential micronutrient, because it is a catalytic and structural cofactor of enzymes that control the basic processes in all cells, and moreover it is a participant in signaling pathways. The toxic properties of copper ions, due to their chemical nature, are manifested when the cellular and/or organism systems for copper homeostasis are disturbed. Aim of the work was to study the relationships between the diet caloric and the copper status in the blood serum, the copper metabolism in the liver and white adipose tissue (WAT) of rats.

The work was performed on three groups (each n=5) of white outbred rats (average body weight 220±15 g), kept for 75 days on a standard, low-calorie (LCR) or high-calorie (high-fat) (HCR) rations. mRNA concentration was measured by qRT-PCR technology. The сeruloplasmin (CP) content was determined by the method of immune electrophoresis, immune blotting and by oxidase activity. The copper concentration was measured by atomic absorption spectrometry.

It has been shown that serum level of triglycerides increased in rats fed LCR. The main indicators of copper status (concentration of atomic copper, the level of holo-CP, and the content of immunoreactive CP) decreased in rats fed HCR. In the liver, none of the diets affected Cp gene expression level. In the cells of the subcutaneous fatty tissue, the concentration of both splice-forms of CP-mRNA significantly increased in rats fed LCR. In visceral adipose tissue the concentration of Cp-mRNA encoding the secretory CP did not change in LCR-rats, but the level of mRNA, encoding CP anchored to plasma membrane, dropped to almost zero as compared to the control group. There was no significant change in the level of both splice-forms of CP-mRNA in HCR-rats. The features of copper metabolism in the cells of the liver and WAT, due to the caloric content of ration, have been discussed.

In rats' liver, the link between copper metabolism and calorie intake is manifested in changes in the expression of the CP gene at the translation level, and in white adipose tissue - at the level of transcription and post-transcriptional maturation of the pre-mRNA of this gene.