Effects of mental challenge on neurovascular responses in healthy male subjects

The purpose of this study was to examine the effects of mental challenge on total antioxidant capacity (TAC), forearm blood flow (FBF), vascular reactivity (VR), and the release of norepinephrine (NE). Furthermore, this study also examined the possible relationships of NE with FBF and VR following the mental challenge. Twenty healthy male subjects participated in twenty minutes of mental stress task (Stroop Color-Word Task [SCW] and mental arithmetic task [MA]). Our results showed that HR and NE increased significantly immediately following the mental challenge, whereas total antioxidant capacity did not change. Furthermore, the area-under-the-curves (AUCs) for both FBF at baseline and during reactive hyperemia, and VR elicited a significant change across time immediately post-stress. The percent change in the HR was partially correlated with the percent change in the VR immediately post-stress (p=0.08). Additionally, the percent change in the NE was positively correlated with TAC immediately post-stress, whereas NE only demonstrated a partial relationship with FBF at baseline immediately following the mental challenge (p=0.10). These findings suggest that forearm vasodilation following the mental challenge may be mediated by the antioxidant defense and sympathetic activation. Further studies are warranted to elucidate the mechanisms that explain the responses and relationships presented in this investigation.