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

Abstract

While sympatho-adrenal medullary (SAM) system and hypothalamo-pituitary adrenal (HPA) axis responses to psychological stress are important in their own accord, the overall response involves integrated reactivity of both pathways. The integrated response was hypothesised to reveal differences not evident in either system alone Age matched lean (n=19) and overweight/obese (n=17) men were subjected to a Trier Social Stress Test and SAM system (SBP, DBP) and HPA axis (salivary cortisol) reactivity measured. Integrated reactivity of SAM and HPA pathways was calculated using ratios. Considering HPA axis relative to SAM system (i.e., HPA/SAM ratio) revealed significantly lower cortisol over SBP (CoSBP; time*condition: F[14, 476]=1.970, p=0.018) and cortisol over DBP (CoDBP; time*condition: F[14, 476]=1.924, p=0.022) reactivity in overweight/obese compared with lean men. Measures of SAM/HPA reactivity were unaltered. Cortisol response per unit of blood pressure response was blunted in men with elevated adiposity. These findings support there being a coordinated overall approach to stress pathway reactivity with the degree of activation in one pathway related to the degree of activation of the other.