The Relationship between the Age of the Based Laboratory Animals (Mice, Rats, Hamsters and Dogs) and the Age of Human: Actuality for the Age-Ralated Radiosensitivity Problem and the Analysis of Published Data

Abstract

Purpose: Survey-synthetic study of published scientific data on the relationship between the ages of the most used laboratory animals (mice, rats, hamsters and dogs) and humans to obtain the corresponding formula dependencies and calibration curves. Basis: The work is a preamble for a more extensive analysis of data on the age-related radiosensitivity of animals as applied to the extrapolation of the revealed patterns to humans. The presented introductory review of the history of research in this field showed that the main works were carried out in the 1950s – 1960s, and, much less, in the 1970s, and the results, apparently, produced almost nothing for practical radiation medicine and radiation safety. Investigations of the relationship between the age and the radiosensitivity for the human which were exposed to total irradiation in significant doses were practically not found although such data are important because of the permanent threat of nuclear incidents and terrorism. In this regard, the quantitative transfer of the corresponding dependencies, identified for various species of animals, on the situation with acute human radiation syndrome continues to be relevant. In its entirety, according to our analysis of sources it has not been carried out until now, including the documents of UNSCEAR, ICRP, WHO, and others. Material and methods: Data on physiological age periods and their boundaries for animals and humans, published in reliable scientific sources, were used for calculations and general analysis. Based on the extracted values (from tables and one chart of originals), using the IBM SPSS and Statistica programs, a formula was derived for the ‘standard’ dependencies on ‘age of the animal – age of the human’ and a corresponding calibration schedule was constructed. Both direct and indirect data were used. In the first case (mice, rats, dogs) we used the data for direct comparison of the age periods of animals and humans and in the second (mice, rats, hamsters) we used the quantitative information about a particular age period for an animal. It allowed us to conduct own comparison of such data with a similar period of human life. Results: ‘Standard’ formulas were derived and ‘standard’ calibration curves were obtained, which made it possible to compare the age of mice, rats, hamsters and dogs with human age. In parallel, it turned out that many of the so-called ‘calculators’ in the English and Russian-language Internet, which can translate the age of almost any animal into human age (according to the statements of their developers), give the mistakes at comparative estimates with the observed dependencies on the basis of scientific data (difference up to 20–60 %). Conclusions: The obtained data fill the existing scientific gaps, creating the prerequisites for both comparison of the parameters of the age-related radiosensitivity of laboratory animals and humans (important for radiation safety) and for use in other experimental areas of biomedical disciplines. On the basis of detailed approaches to the problem considered in the paper, it is possible to derive similar relationships for the age of any other animal and human.