ACTH Secretion in Midbrain-Transected Rats

Abstract
During the first 2 days after operation "resting" plasma corticosterone levels were high, but thereafter returned to normal in both midbrain-transected and sham-operated animals. Ether anesthesia induced a significant rise in plasma corticosterone 48 hr. after midbrain transection. Three days after operation dexamethasone suppressed plasma corticosterone levels to an equivalent level in both midbrain-transected and sham-operated rats. It is concluded that the hypothalamic-adenohypophysial complex is capable of regulating ACTH release in response to selected stimulatory and inhibitory influences in midbrain-transected rats. No evidence was found to substantiate that the effect of a "tonic inhibitory neural center" on ACTH release is abolished by midbrain transection.