Meeting Abstract
Because of its critical role in reducing glucocorticoids after exposure to stressors, many researchers have become increasingly interested in assessing hypothalamic-pituitary-adrenal (HPA) negative feedback. Although assessing negative feedback in a standardized way using injections of the synthetic glucocorticoid dexamethasone is a straightforward procedure, there are several defensible ways to quantify negative feedback efficacy, each of which incorporates various aspects of HPA physiology. Here, we report seven different methods for reporting HPA negative feedback and their prevalence in the comparative endocrinology literature, and reanalyze a dataset of wild house sparrows (Passer domesticus; n=58) caught during six different times of year to show that even though most of these approaches give values that are correlated with each other, they yield distinct (and even opposing) statistical results. Because the approach used to quantify negative feedback matters so much for the end results, we encourage researchers to converge on a common method for reporting HPA negative feedback, report multiple measures, or at the very least, make their raw data available so alternative measures can be calculated. We also advise caution in comparing results among studies using different approaches to assess HPA negative feedback.
