Detection of miRNAs in HPA Axis Function in Healthy Subjects

The proposed study will test dexamethasone effect on miRNA profile in healthy humans. As our data indicate that miRNA levels change over time, the investigators will study the time course of miRNA response to 1 mg IV dexamethasone within 60 minutes after injection. Dexamethasone is used routinely in human subjects for the treatment of inflammatory conditions and as a diagnostic tool in the evaluation of excess cortisol secretion (Cushing's syndrome). For the latter, 1 mg dexamethasone is given orally at midnight. Oral formula absorption in the gut can range from 20 to 60 minutes due to the presence of food and other factors. IV administration will bypass this variability and ensure an accurate and reproducible time-course study. The investigators will compare miRNA expression before and after dexamethasone treatment. The investigators will follow miRNA expression dynamics over a 1-hour time course to identify peak expression levels and to correlate miRNA expression with circulating dexamethasone levels. Dexamethasone and miRNA levels will be checked at baseline just before injection and then at 15, 30, 45, and 60 minutes after injection. Dexamethasone level is taken to verify treatment and to correlate it with miRNA expression.