Stress system dysfunction revealed by integrating reactivity of stress pathways to psychological stress in lean and overweight/obese men

Although the patterns of response within the sympathoadrenal medullary (SAM) system and hypothalamo-pituitary adrenal (HPA) axis are interesting and important in their own accord, the overall response to acute psychological stress involves reactivity of both pathways. We tested the hypothesis that consideration of the integrated response of these pathways may reveal dysregulation of the stress systems, which is not evident when considering either system alone. Age-matched lean and overweight/obese men were subjected to a Trier Social Stress Test and reactivity of the SAM system (salivary α-amylase, systolic blood pressure, diastolic blood pressure, and heart rate) and the HPA axis (salivary cortisol) were measured. Relative reactivity of SAM system and HPA axis was calculated as the ratio between the measures from each pathway. Although analysis of reactivity of individual stress pathways showed no evidence of dysfunction in overweight/obese compared with lean men, analysis of HPA/SAM reactivity revealed significantly lower cortisol over systolic blood pressure (CoSBP) and cortisol over diastolic blood pressure (CoDBP) reactivity in overweight/obese compared with lean men. Other measures of HPA/SAM reactivity and all measures of SAM/HPA reactivity were unaltered in overweight/obese compared with lean men. These findings suggest that the cortisol response per unit of blood pressure response is blunted in men with elevated adiposity. Furthermore, these findings support a notion of a coordinated overall approach to activation of the stress pathways with the degree of activation in one pathway being related to the degree of activation in the other.