The aim of the present study was to examine whether the amount of oral antimicrobial components, human β-defensin-2 (HBD-2), LL-37, and immunoglobulin A (IgA) might be affected by a single bout of intense exercise, and to determine whether the activities of two main neuroendocrinological systems, the hypothalamus-pituitary-adrenal (HPA) axis and sympathetic and adrenomedullary (SA) systems, to physical stress might be differentially or synergistically associated with these immunological changes. Seven young male volunteers either exercised on a recumbent ergometer at 75% V・O2max for 60 min (exercise session) or sat quietly (resting session). Saliva and blood samples were obtained at 60 min intervals during sessions for measurements of saliva antimicrobial components (HBD-2, LL-37, and IgA), hematocrit, and hemoglobin. Saliva cortisol and plasma norepinephrine were also determined at the same time points as a measure of activities of the HPA axis and SA system, respectively. Saliva levels of HBD-2 and LL-37 were increased during and after exercise, whereas saliva IgA was decreased after exercise. Saliva cortisol and plasma norepinephrine levels were increased during exercise. While the areas under the curve (AUC) of the time courses of saliva levels of HBD-2 and LL-37 were positively associated with those of plasma norepinephrine, the AUCs of saliva HBD-2 and LL-37 were negatively associated with those of cortisol levels in saliva. In contrast, the decreases in salivary IgA levels were not associated with changes in any stress-related parameters examined. The present findings raise the possibility that the activities of the HPA axis and the SA system during strenuous physical stress might differentially affect both oral HBD-2 and LL-37 levels, but not those of IgA.
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