Role of the medial hypothalamus in regulation of the pituitary-adrenocortical system.

Chronic experiments on rabbits showed that bilateral electrolytic destruction of dorosomedial and ventromedial hypothalamic nuclei lowers the basal blood corticosteroid levels. Stimulation of the dorsal tegmentum, which in intact animals causes the blood corticosteroids to rise, no longer leads to an increase in the adrenocortical hormone level after destruction of these nuclei. It is concluded that the medial hypothalamus has a tonic activating influence on basal secretion and participates in transmission of activating influences from the midbrain to the adrenal cortex.