"Refinements in the assessment of stress in laboratory animals: non-invasive fecal corticosteroid determination"

J. Hau,

Department of Experimental Medicine, University of Copenhagen and University Hospital, Copenhagen, Denmark

Substantial stress is associated with an activation of the Hypothalamus-Pituitary-Adrenal axis resulting in a rapid - almost instantaneous - increase in the levels of corticosteroids in the circulation of the individual. Quantification of serum corticosteroids normally requires restraint and blood sampling. Both are procedures that will generally result in stress-associated increases of corticosteroids in the blood rendering this approach to stress assessment problematic and associated with a degree of uncertainty. Excretion and secretion changes in relevant glucocorticosteroids in saliva, urine, and faeces may be used in the assessment of preceding acute stress in a number of animal species. An advantage of quantifying corticosteroids and relevant corticosteroid-metabolites in urine and faeces is that the total excretion of the molecules in any time window chosen can be measured and expressed as amount excreted per hour per kg body weight. This is in contrast to e.g. quantification of corticosteroids in the total circulation of the animal from quantitative measures in blood samples, which will require integration of the area under the curve. We have used the non-invasive approach to assess stress associated with uncomfortable housing and common procedures such as anaesthesia and surgery. Metabolic cages are often used in biomedical research and it is debated whether housing in these cages is more stressful than single housing in standard caging, and how long time the animals need to acclimatize when they have been transferred to metabolism cages. There is scant information on animals' responses to metabolic cages and our results from studies of a few different laboratory animal species will be presented. Anaesthesia and surgery are routine procedures in laboratory animals and results from stress assessment of these by quantitative measures of fecal corticoid excretion will be presented.  In my research group -  1991-1996 London University, 1996-2007 Uppsala University and from 2004 University of Copenhagen - we have gained considerable experience with the pros and cons of various stress sensitive molecules quantified in saliva, urine and feces and this experience will be presented and discussed at the meeting.