The chewing-related neuronal mechanism underlying stress relief, was evaluated by use of fMRI. For this purpose we examined the effect of chewing a moderately hard gum without any taste (X type, Lotte Co. LTd., Tokyo) on brain activation caused by a noisy sound stress, on plasma levels of catecholamines and ACTH. The stress significantly increased the blood oxygenation level-dependent (BOLD) signals in the amygdala and the medial prefrontal cortex, and elevated plasma levels of noradrenaline, dopamine and ACTH. However, this chewing suppressed not only the stress-induced increase in BOLD signals in these two regions, but also the stress-induced elevation in plasma levels of these catecholamines and ACTH. The results suggested that chewing might be a useful therapy for reducing stress.
Stress ; Mastication ; Adrenocorticotropic hormone measurement ; Plasma ; Stress bismuth subsalicylate