Reference intervals of mice organs mass coefficients and absolute weight
Organ weight analysis in toxicological studies is an important endpoint for identifying target organs in test system. In this article, reference ranges for organ weight ratios of outbred mice (ICR CD-1), as well as their absolute values, are determined. Data on the organs weight of mice were obtained on the basis of control groups of toxicological studies conducted at the research and manufacturing company «HOUSE OF PHARMACY» for the period 2017-2021. The age of the animals at the time of necropsy was 12-18 weeks. The studies were performed in compliance with the principles of the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes and in accordance with the rules of Good Laboratory Practice. In accordance with the recommendations of the Society for Toxicological Pathology (STP), the weight of the following organs was recorded in experimental mice: liver, heart, kidneys, brain, spleen, thymus, testes. Additionally, the lungs weight with the trachea was analyzed. Due to the small size of the adrenal glands and ovaries, these organs weight was not recorded. To account the biological variations between animals, the body weight of the animal has to be taken into consideration when analyzing the organ weight statistically. Normalization of organ weights to body weight reduces the variations due to body weight differences in animals, at the same time extreme increase or decrease in body weight may results in sham interpretation. When there is significant change in body weight, organ-to-brain weight ratios may be useful, as brain weight does not change with change in body weight. Thus, there are various methods for assessing organ weights in toxicity studies, so organ weight ratios relative to body and brain weights, as well as absolute organ weight, were analyzed to form reference intervals. For the data, a non-parametric method for determining reference intervals was applied. In samples for mass coefficients of organs, the values number on average was more than 120, for absolute coefficients of organs - more than 60. There were no differences in the ratio of emissions mass coefficients relative to the animal»s body weight and brain weight in female mice, but in males the smallest amount of emissions was found when calculating the organs coefficients mass relative to the body weight of animals.