Non-invasive monitoring of stress hormones in rodents and its application in biomedical research

Touma C

Research Group of Psychoneuroendocrinology, Max Planck Institute of Psychiatry, Munich, Germany; e-mail: touma@mpipsykl.mpg.de

Rodents represent the vast majority of all vertebrates used for research worldwide. In particular, mice are extensively utilized as animal models in the biomedical sciences. They are easy to handle and breed, and can be easily kept in large numbers. Moreover, established techniques allow genetic manipulations, generating transgenic and knockout mice that are increasingly used in diverse areas of research. However, due to their small body size and the invasiveness of common blood sampling techniques, the monitoring of endocrine functions is seriously constrained. Measuring steroid hormone metabolites from faecal samples could overcome this problem.

Using faecal samples offers several advantages such as easy collection and feedback-free sampling, thereby avoiding all stress effects associated with blood sampling. Furthermore, as there is no need to capture and handle the animal, repeated sampling of the same individual is possible without affecting its endocrine status. This allows measuring short-term hormonal changes (e.g. before and after drug treatment or social encounters) as well as long-term monitoring of endocrine profiles (e.g. during the course of a disease or therapeutic treatment). Additionally, the diurnal variation of glucocorticoids can be followed repeatedly in individual animals. Thus, this technique facilitates investigating endocrine features in mice that are hardly detectable using conventional methods and can significantly contribute to the ‘Reduction’ and ‘Refinement’ recommended in the ‘Three R’ concept.

In this talk, I will present our studies performed to develop and extensively validate the measurement of glucocorticoid metabolites in faecal samples of mice and also highlight studies applying this non-invasive technique to monitor stress hormones as a powerful tool in biomedical and animal welfare research. These insights about important factors influencing the metabolism and excretion of glucocorticoids will also be of high value for other rodent species and can be crucial for appropriately designing studies in captivity and in the field.