Adrenocortical Response to Ovine Corticotropin-Releasing Hormone in Young Men: Cortisol Measurement in Matched Samples of Saliva and Plasma

Abstract

Background: Assessment of hypothalamic-pituitary-adrenal (HPA) axis function in stress-related health problems in humans is frequently carried out as a dynamic test by measuring the profile of increment in adrenocortical hormone (ACTH) and/or cortisol level in plasma in response to corticotropin-releasing hormone (CRH) administration. However, obtaining multiple blood samples for this type of test is not only an invasive procedure but also problematic to use in individuals with constricted or damaged veins which collapse during the blood draw such as the injecting drug users (IDUs) and HIV-1-infected individuals. Salivary cortisol measurement presents a non-invasive alternate approach to evaluate HPA axis activity in different situations. In order to validate the efficacy of salivary cortisol measurement for a dynamic test in IDUs and HIV-1-infected individuals, the present study was carried out to evaluate the cortisol profile in matched samples of plasma and saliva in healthy young men in response to ovine CRH (oCRH) administration. Methods: Cortisol levels were measured in matched samples of plasma and saliva of healthy young men at baseline and over a 90-min period after administration of a single low dose of oCRH (1 µg/kg). Results: Salivary cortisol levels were found to follow the profile similar to that of plasma, increasing significantly at each time point after oCRH administration from their respective baseline values (all Sign tests, p < 0.05). The peak level of cortisol occurred at 30 min in both fluids. Although salivary cortisol concentration was a fraction of the total plasma cortisol levels at all time points, there was a significant correlation in the values between the two fluids at baseline (r = 0.87, p < 0.02) as well as at 90 min (r = 0.70, p < 0.03). Conclusion: The findings support the earlier studies and substantiate the efficacy of using salivary free cortisol measurement for assessment of dynamic function of pituitary-adrenal axis in healthy young men and its application in individuals such as IDUs and HIV-infected individuals who may have difficulty in donating multiple blood samples.