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Johns Hopkins Bloomberg School of Public HealthCAAT

Animal Welfare Enhancement Awards - 2005 Recipients

Development and validation of a fecal steroid assay to non-invasively measure hormone levels
Matthew B. Lovern, PhD
 Oklahoma State University

Steroid hormones profoundly influence virtually every aspect of vertebrate biology, including development, growth, reproduction, behavior, and in many cases, health. As a result, steroid levels are measured in a variety of organisms and for numerous reasons. The green anole lizard is a widely-used laboratory model for elucidating steroidal effects. However, the typical method of sampling steroids — blood collection — is moderately invasive, is likely stressful to the individual, and can not be performed repeatedly, due to this lizard's small size. A non-invasive sampling method for measuring steroids would thus be useful for reasons of both experimental design and animal welfare, not only in this species but also in other small lab animals as well. In addition to their presence in blood plasma, steroids are excreted in feces. Therefore, the goal of the present research is to develop and validate a fecal radioimmunoassay for detecting steroid levels in green anole lizards. This method of sample collection is entirely non-invasive, and could be generalized to other species. Because plasma samples represent a snapshot of an organism's endocrine status, whereas fecal samples represent a cumulative secretion since the last defecation, plasma and fecal levels of the steroids testosterone, estradiol, and corticosterone will be compared between adult male and female green anoles housed under standard laboratory conditions. This work is expected to show that steroids can be detected in fecal samples from green anoles, and that biologically meaningful results can be obtained, thus providing researchers with a non-invasive technique for measuring steroids.