Effect of electrical stimulation of the canine brain stem on the secretion of ACTH and growth hormone (GH).

The effects of electrical stimulation of the brain stem on ACTH and GH secretion were studied in pentobarbital-anesthetized dogs. Stimulations in or near the subcoeruleus area or ventral ascending noradrenergic pathway inhibited the stress-induced increase in ACTH secretion, while stimulations in other areas of the brain stem did not. No significant changes in GH secretion occurred following stimulation of the subcoeruleus area, ventral ascending noradrenergic pathway or adjacent regions of the canine brain stem. These results are consistent with the hypothesis that there is central noradrenergic input to the hypothalamus which can inhibit ACTH secretion. This input appears to be separate from the postulated noradrenergic input that may increase the secretion of GH.