[The central gray substance of the midbrain: the role of corticosteroids in the analgesic effect].

: The effect of stimulation of periaqueductal gray matter on pain threshold and blood corticosteroids was studied in anesthetized rats. The stimulation with 30-50-microA current resulted in an increase of analgesia and blood corticosteroids. An increase of current intensity up to 100 microA resulted in a decreasing corticosteroid level and analgetic effect. The magnitude and duration of the analgesia were decreased after blocking the pituitary-adrenocortical system. The corticosteroids seem to induce analgesia after stimulation of periaqueductal gray matter stimulation.