Circadian profile of basic metabolism indicators in mice of the lines Balb/c and Balb/c nude

Mice of the Balb/⁠c and Balb/⁠c nude lines are widely used in oncology as a tool for preclinical testing of antitumor drugs. Balb/⁠c nude and Balb/⁠c mice may differ in biological parameters of basal metabolism. The aim of the work is to study the metabolic indices reflecting the rhythm of biological processes in Balb/⁠c and Balb/⁠c nude mice. The study was conducted on 24 female and male mice. In the autumn period, for two months: in the morning, afternoon and evening, the intensity of metabolism was studied by the indirect calorimetry method. The change in average oxygen consumption (VO2, ml/⁠h), average volume of produced carbon dioxide (VCO2, ml/⁠h) in metabolic chambers was estimated, and the metabolic quotient was determined — VCO2/⁠VO2 c. u. The measurements were adjusted for the animal’s body weight: VO2/⁠M and VCO2/⁠M (M = body weight in kg). The intensity of heat production (IT, kcal/⁠kg/⁠h) was estimated taking into account VO2, VCO2 per unit of time and animal weight. Statistical processing was performed using the Statistica 10 program. The results of the study showed that the values of metabolic parameters in Balb/⁠c nude and Balb/⁠c mice changed during the daylight hours. Differences in metabolism were depending on gender. In the morning, the highest metabolism was observed in Balb/⁠c nude males, and the lowest — in Balb/⁠c males. In terms of metabolic parameters, Balb/⁠c females approached the high values of Balb/⁠c nude males, while Balb/⁠c nude females approached the low values of Balb/⁠c males. In the evening, the metabolic of males remained the same, while those of females changed: most of the values of the studied parameters in Balb/⁠c nude female mice prevailed over the corresponding parameters in Balb/⁠c females. Thus, data were obtained on the difference in the basal metabolism parameters in Balb/⁠c and Balb/⁠c nude mice of different sexes during daylight hours, with the most pronounced differences in the morning hours, which must be taken into account when conducting preclinical studies. The obtained data will serve as a starting point for studying the features of the basal metabolism in animals with experimental tumors.