Measuring salivary cortisol in the behavioral neuroscience laboratory

It is often difficult for instructors teaching laboratory courses in behavioral neuroscience to find appropriate experiments that can ethically examine biological parameters in human participants. In most instances, the default experiments that allow students to act as both experimenter and subject tend to be electrophysiological in nature (e.g., EEG, GSR, etc.). We report here the use of an experiment module that utilizes an easily-obtained enzyme immunoassay (EIA) kit to measure human salivary cortisol. Cortisol is a hormone of the adrenal cortex that can be used as a peripheral indicator of hypothalamic neural activity. Plasma (and salivary) cortisol levels rise due to circadian influences as well as perturbations in the organism's environment (i.e., stressors). The involvement of the hypothalamic-pituitary-adrenal (HPA) axis in the pathophysiology of depression makes this an appealing module to students in behavioral neuroscience laboratories. Measurement of salivary cortisol takes advantage of a simple, painless, non-invasive sampling procedure. The assay can be performed successfully by anyone with access to a plate reader, a shaker or rotary mixer, and a few commonly used pipettors. A single plate assay can be completed in two to three hours. Students in our behavioral neuroscience laboratory class have utilized this kit successfully to examine the circadian cortisol rhythm as well as the effect of stress/relaxation on cortisol levels.