Abstract
We observed changes. in contents of noradrenaline (NA) and its principal metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-S0.) in rat brain regions during 180 min. of stress combined immobilization with electric tail shock, and studied relationship between changes in these substances and gastric mucosae. The hypothalamus and amygdala showed decreases of NA contents already within 15 min. prior to the occurrence of gastric mucosal lesions which appeared after 30 min. This finding suggests that the rapid response of noradrenergic neurons in these regions plays a significant role in producing gastric mucosal lesion. Complete abolishment of glucocorticoid secretion by bilateral adrenalectomy potentiated the stress-induced increases of MHPG-S0. Ievels in the hypothalamus, amygdala and hippocampus, and the accelerated metabolisms of NA in the hypothalamus and hippocampus of adrenalectomized animals exposed to the stress were reversed by supplementary administration of corticosterone. It is suggested that glucocorticoid secreted via pituitary-adrenocortical system plays an inhibitory role in the responses of brain noradrenergic neurons to the acute stress.
