[Body composition and morphometric parameters of rats at the different provision levels with macroand micronutrients]

The modern trend to the food industry's resource base expanding requires continuous improvement of safety assessment approaches of the novel food sources and the exploring of toxicological and allergological research updated algorithms, the development of in vivo, in vitro and in silico models, as well as the formation of specific biomarkers profiles and the establishment of physiological fluctuations ranges for the studied indicators. To increase the information content of toxicological studies and identify hidden negative effects associated with the novel food consumption, in vivo models of reducing the adaptive potential of laboratory animals were developed. The analysis of the data obtained in experiments using these alimentary models demonstrated the need to determine the norm boundaries of individual morphofunctional parameters. The purpose of the study was to investigate the body composition and some morphometric parameters in rats against the background of key macro- and micronutrients' deficiency in the diet.

The experiment lasting 64 days was carried out on 80 male Wistar rats with an initial body weight of 134.7±3.8 g. The animals were divided into 5 groups of 16 rats each: the control group received a standard semi-synthetic casein diet, the 1st-4th test groups were fed diets with a deficiency of protein, fat, carbohydrates and some micronutrients (vitamins B1, B2, B3, B6, iron and magnesium salts), respectively. Within the experiment gravimetric and morphological (histological and morphometric) studies of the liver, heart, kidneys, and testes were performed, so as the dynamics of the body's component composition (by quantitative magnetic resonance using the EchoMRI 500 tissue analyzer) were studied.

Dietary fat deficiency had the least effect on the weight and body composition of growing animals (the differences between the studied indicators and the control values were no more than 1%), carbohydrate deficiency led to a decrease in body weight by 11.4%, fat mass by 39.7%, lean mass and total water by 9.4%; micronutrient deficiency led to a decrease in body weight by 53.3%, fat mass by 96.4%, lean mass and total water by 51.0%; protein deficiency led to a decrease in body weight by 74.8%, fat mass by 97.0%, lean mass and total water by 73.5%, respectively (p<0.05). The sizes of the structural elements of the liver, heart, kidneys, and testes under diet deficiency of fat differed from the control by 1-9%; of carbohydrate - by 2-7%; micronutrients - by 8-56%, protein - by 14-65%, respectively. The most pronounced changes in body weight and composition, as well as the size of the structural elements of internal organs, were found in animals kept on diets deficient in protein and micronutrients.

Based on the data analysis the influence degree of the nutrients on the studied parameters was established. The most pronounced changes in body weight and composition, the mass of internal organs, as well as the size of the liver, heart, kidneys, and testes structural elements were found in animals kept on protein-deficient diet. The lack of micronutrients (vitamins B1, B2, B3, B6, iron and magnesium) was on the second place in terms of the impact degree on these indicators. The lack of fat and carbohydrates in the diet had virtually no effect on body composition and the microstructure of internal organs. Thus, the availability of protein and micronutrients plays a primary role for the complete morphogenesis of mammals at both the micro and macro levels.