The state of metabolic parameters of the blood in white rats under conditions of long-term oral administration of gadolinium orthovanadate nanoparticles under food stress

The prohibition of using antibiotics with growth-stimulating properties in the European Union led to the search for new, safer, more effective, and cheaper feed additives. One of these substances was rare earth elements (REE, atomic numbers 57–71) due to their low toxicity and protective and antioxidant properties. At the same time, higher efficiency of organic forms of REE was noted. Thanks to this, it is possible to assume their even more pronounced effect in nano-sized form as feed additives and the need to conduct research in this direction. Therefore, this work aims to study the metabolic parameters of the blood in rats under long-term oral administration of nanoparticles of one of the representatives of rare earth elements – gadolinium orthovanadate (NP GdVO4:Eu3+) under food stress. Experimental samples of gadolinium orthovanadate nanoparticles activated by Europium (spindle-shaped geometry; size 8×25 nm; initial concentration 1.0 g/dm3) were used in work. Experimental studies on rats were carried out based on the vivarium of the NSC “IEKVM”. The object of research was 140 mature male Wistar rats with an initial weight of 180–200 g. Four groups of animals, 35 rats each, were formed according to the principle of analogs. During the experiment, animals of the control group received drinking water without additives; rats of the І experimental group were given a solution of NP GdVO4:Eu3+ at a dose of 0.2 mg/dm3 (≈ 0.03 mg/kg of body weight); II research group – at a dose of 1.0 mg/dm3 (≈ 0.15 mg/kg of body weight) and rats of III research group – at a dose of 2.0 mg/dm3 (≈ 0.30 mg/kg of body weight). Drinking was carried out for 56 days, then it was completed, and the rats were observed for another 14 days. A nutritionally unbalanced diet was used as a stress factor. Taking into account the results of biochemical studies, the adaptogenic effect of NP GdVO4:Eu3+ in the range of doses of 0.2–1.0 mg/dm3 of drinking water (≈ 0.03–0.15 mg/kg of body weight) on the body of white rats was established under conditions of food stress with optimal duration of action – 28–42 days. Under the conditions of administration at a dose of 2.0 mg/dm3 of drinking water (≈ 0.30 mg/kg of body weight), a hepatic(cyto-)toxic effect of nanoparticles was detected, which was accompanied by an irreversible decrease in the structural indicators of lipid metabolism, the consumption of antioxidant resources and the induction of intensity processes of lipid peroxidation against the background of alanine aminotransferase hyperenzymemia.