Specificity of corticotrophin-induced increase in mitochondrial ribonucleic acid

¹ Departments of Medicine, King County Hospital System, and University of Washington School of Medicine, Seattle, Washington

Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) were measured in subcellular fractions of pooled adrenals removed from rats 4 hr after injection of agents known to affect or suspected of altering adrenal intermediary metabolism. Corticotrophin (2 µ) increased mitochondrial RNA 29% over that of saline-injected animals and 74% over uninjected controls. Nuclear DNA and nuclear and microsomal RNA were unchanged. Thyrotrophin (2 µ), growth hormone (1 µ), chorionic gonadotrophin (500 µ), triiodothyronine (25 µg), p-dinitrophenol (50 µg), crude parathyroid hormone (10 µ), and vasopressin (0.4 µ) failed to affect either nucleic acid. The mitochondrial-adrenal weight ratio increased only in corticotrophin-treated animals. The percentage increase of mitochondrial RNA exceeded that of mitochondrial weight. Conjugated estrogen was the only other agent that produced a response. One, five, and ten micrograms increased DNA in spayed female rats while 50 µg produced no effect. Estrogen presumably affected cell division. A part of the sequential response of adrenal intermediary metabolism to corticotrophin includes a specific increase in the nucleic acid content of that organelle associated anatomically with steroidogenesis.

Key Words: corticotrophin effect on nucleic acid • deoxyribonucleic acid • ribonucleic acid • adrenal mitochondria • estrogen effect on DNA

Submitted on October 10, 1963