Studies on the production and metabolic clearance rates of cortisol in the European eel. Anguilla anguilla (L.)

Abstract

Aspects of cortisol metabolism have been studied in the eel, Anguilla anguilla L., adapted to fresh water and sea water environments. The effects of hypophysectomy and removal of the corpuscles of Stannius on cortisol dynamics were assessed. High specific activity tritiated cortisol reached a steady state in plasma 7 h after beginning a constant intravenous infusion. Plasma cortisol concentrations were determined in hourly blood specimens during the steady state situation. Plasma cortisol concentration, its metabolic clearance and production rates were obtained for the various experimental groups. Plasma electrolytes were also determined. Similar cortisol concentrations occur in fresh water and sea water eels. Sea water adapted eels had higher metabolic clearance and production rates than fresh water animals. After hypophysectomy both fresh water and sea water adapted eels had reduced plasma cortisol concentrations and cortisol production rates, although the metabolic clearance rates were significantly elevated. These alterations in cortisol dynamics following hypophysectomy were returned to normal by infusion of mammalian ACTH in a group of sea water adapted eels. In fresh water eels removal of the corpuscles of Stannius produced almost twofold increases in the metabolic clearance and production rates of cortisol without there being any change in plasma cortisol concentration. Removal of the corpuscles of Stannius from sea water adapted eels induced a slight decrement in plasma cortisol concentration.