Bilateral secretory responses of the adrenal medulla during stimulation of hypothalamic or mesencephalic sites

Bilateral secretion of epinephrine and/or norepinephrine from adrenal medullae occurred in 76% of cats studied following unilateral electrical stimulation of sites in the hypothalamus or rostral mesencephalon. Responses were generally greater on the ipsilateral side. In most experiments, epinephrine alone or both epinephrine and norepinephrine outputs were increased. In only two experiments norepinephrine output was increased. Stimulation of most hypothalamic sites that evoked bilateral secretion was accompanied by an increase in blood pressure. Stimulation of effective sites in the mesencephalon was not generally accompanied by blood pressure changes.