Non-invasive endocrine monitoring in urine and feces of mammals: the importance of validation.

PONZIO M.F

Nuremberg

Conferencia; Invited Special Workshop, Nuremberg Zoo; 2015

Nuremberg Zoo

Traditionally, studies on reproductivephysiology and stress response in mammals have been based on the determinationof endocrine activity of hormones associated with these processes in plasma.However, extraction of blood samples is, in itself, a procedure that can modifyplasma cortisol levels and in turn negatively impact the expression of thehypothalamic-pituitary-gonadal axis. Furthermore, plasma levels of certainhormones fluctuate widely as a result of pulsatile secretion and / or circadianrhythms and therefore each blood sample provides a static data of a parameterthat is variable, so that multiple samples would be required for a reliablenotion of the hormone secretory activity over time. For this reason, an efficient alternativedeveloped in recent years, is the non-invasive monitoring of steroid hormonemetabolites excreted in various matrices as feces, urine, saliva, hairs etc.Its usefulness has been extensively tested in many species. With the implementationof animal welfare policies and research methodologies based on the 3 Rs thistechnique is also being used in laboratory animals. Its main benefit is thatwith the use of animal handling, stress and risks associated with repetitivepuncture is avoided. The sample collection may be performed over prolongedperiods of time and finally, the assays used are relatively simple, efficientand easy to adapt from one species to another. Using the non-invasive techniquewe can study topics as diverse as reproductive cycles, seasonal variations inhormone levels, sexual and behavioral differences associated with hormones,association between hierarchical positions, thyroid function, effects ofenvironmental toxins on endocrine function, stress and hormone levels witheffects on reproduction and the effects of human activities on animal welfare.However, implementation of the laboratory techniques associated with thisdiscipline emphasizes its previous validation, aspects that will be consideredin this dissertation.