RT Journal Article SR Electronic T1 STUDIES ON THE CORTICAL CONTROL OF THE ADRENAL MEDULLA IN THE RAT JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 227 OP 238 VO 162 IS 2 A1 LARISSA POHORECKY A1 JOHN H. RUST YR 1968 UL http://jpet.aspetjournals.org/content/162/2/227.abstract AB Morphologic and biochemical changes in the adrenal medulla of rats were followed with time after hypophysectomy. Phenylethanolamine-N-methyl transferase (PNMT) activity decreased very rapidly; i.e., there was a 50% fall within about 4 days. The decline in epinephrine concentration was gradual; epinephrine concentration had decreased by one-half in 50 days. With the light microscope, an increase in the size of the islets of norepinephrine-containing cells was seen on the periphery of the adrenal medulla 50 days after surgery. Ultrastructurally, the decline in the average number of electron-dense granules was marked in epinephrine-containing cells. Hypertrophy of the rough endoplasmic reticulum and the Golgi apparatus was evident in cells almost devoid of granules. There was a correlation between the decline in the average number of granules per epinephrine cell and the fall in epinephrine concentration. Norepinephrine cells were less affected. Electron-dense granules of small size and the presence of both epinephrine and norepinephrine granules in one cell were seen from 17 days on after surgery. ACTH and dexamethasone treatment of hypophysectomized rats resulted in an increase in PNMT activity, epinephrine concentration and the average number of electron-dense granules in epinephrine as well as in an increase in the average number of granules in norepinephrine cells. © 1968 by The Williams & Wilkins Co.