EVALUATE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS AND SYMPATHETIC NERVOUS SYSTEM

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Certain psychological factors, including depression, are risk factors for the development of diabetes and cardiovascular disease but the mechanism remains unclear. Neuroendocrine changes induced by these psychological factors, specifically activation of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS), might provide a unifying explanation. One limitation to assessing HPA axis activity in large population-based epidemiological studies as a risk factor for diabetes and cardiovascular disease has been the lack of a reliable, easy measurement to assess its function. The gold standard, a 24-hour urine collection for free cortisol, is cumbersome to perform in large-scale studies and is subject to variability. We hypothesize that salivary cortisol and adrenal volume are tightly correlated with HPA axis activity (as measured by 24-hour urine free cortisol) and therefore represent feasible approaches for assessment of HPA axis activity in large-scale cohort and epidemiological studies. The aims of this study are to 1) enroll 50 African-American women ages 18 to 45 years into an overnight GCRC study; 2) obtain measures of psychological traits, anthropometry, and biochemical parameters; and 3) to conduct statistical analyses to determine the following correlations: (a) 24-hour urine free cortisol with total, 8am, and 11 pm salivary cortisol and with adrenal volume; (b) insulin sensitivity and body-mass index with 24-hour urine free cortisol, adrenal volume, and salivary cortisol; and (c) psychological factors with 24-hour urine free cortisol, adrenal volume, and salivary cortisol. Identifying reliable, efficient measures of HPA axis activity will allow them to be incorporated into large, prospective cohort studies of cardiovascular disease and diabetes to determine if HPA axis hyperactivity is a risk factor for these two important diseases, which are significant public health burdens.