Effect of hypoxia on secretion of ACTH in the rat

¹ Department of Pharmacology, Ohio State University College of Medicine, Columbus, Ohio

Body weights, organ weights, and blood and pituitary ACTH concentrations were determined in rats exposed continuously to 20.9, 15.0, or 10.0% O₂ atmospheres at normal barometric pressure for periods ranging from 3 to 120 hr. Hypoxia resulted in some loss of body weight, and loss of weight of the thymus and the ovary. The weight of the adrenals increased. Blood ACTH rose rapidly after exposure to hypoxic conditions, remaining elevated for the duration of the experiment. Control animals (20.9% O₂) placed in the same chamber had detectable blood ACTH only at the 3-hr sampling time. Pituitary ACTH also rose rapidly during hypoxia, the elevation being greatest with the most severe hypoxic state. The rate of ACTH synthesis and secretion in the resting state and during the stress of hypoxia is discussed.

Key Words: pituitary • blood ACTH concentration • pituitary ACTH concentration • rate of ACTH secretion • adrenal thymus • ovary

Submitted on September 11, 1964