GENERAL AND COMPARATIVE ENDOCRINOLOGY 85, 308-315 (1992) The Effect of Anoxic Submergence and Recovery on Circulating Levels of Catecholamines and Corticosterone in the Turtle, Chrysemys picta K.M. KEIVER, J. WEINBERG,* AND P. W. HOCHACHKA Departments of Zoology and *Anatomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 2A9 Accepted March 3, 1991 The ability of some freshwater turtles to tolerate prolonged anoxia is well known. The role of hormones in the regulation of the metabolic adjustments that occur during anoxia, how- ever, is unknown. This study examined the changes in plasma glucose, lactate, catechol- amine, and corticosterone levels during submergence anoxia and recovery at 22°C in the painted turtle, Chrysemys picta. Plasma catecholamine levels increased greatly during an- oxia, while corticosterone levels decreased. During recovery from anoxia, plasma catechol- amine levels fell rapidly while corticosterone levels increased IO-fold over controls. The results are consistent with a role for the catecholamines and corticosterone in the regulation of glucose metabolism in the turtle during anoxia and recovery, respectively. We hypoth- esize that the catecholamines function to stimulate hepatic glycogenolysis during anoxia and thereby increase plasma glucose levels. Corticosterone may function in the recovery from anoxia by enhancing the resynthesis of liver glycogen from lactate. o 1~2 Academic press, hc. Some species of freshwater turtles have a remarkable ability to withstand anoxia. Al- though many of the metabolic adjustments that enable turtles to tolerate anoxia have been elucidated (Jackson, 1968; Clark and Miller, 1973; Jackson and Heisler, 1982; Herbert and Jackson, 1985), the role that hormones may play in the regulation of these adjustments is unknown. During anoxia, turtles must meet their energy demands through anaerobic metab- olism. The primary fuel for anaerobic me- tabolism in anoxic turtles is glucose derived from the breakdown of hepatic glycogen stores (Daw et al., 1967; Clark and Miller, 1973). Blood glucose levels increase during anoxia (Daw ef al., 1967; Clark and Miller, 1973; Penney, 1974) and blood flow to the brain is enhanced at the expense of other organs (Davies, 1989). The supply of glu- cose to tissues such as the brain appears to be essential for the survival of the turtle during anoxia (Sick et al., 1982, 1985). Anoxia, or hypoxia, has been associated with increases in plasma catecholamine lev- els in many animals (Hance et al., 1982; Hudson and Jones, 1982; Boutilier et al., 1988), including the painted turtle (Wasser and Jackson, 1987). Catecholamines are speculated to maintain circulatory adjust- ments (Rose et al., 1983; Padbury et al., 1987; Withers et al., 1988a) and function in glucose regulation during hypoxia (Padbury et al., 1987; Jones et al., 1988). Catechol- amines are known to stimulate hepatic gly- cogenolysis in most vertebrate groups (Hems and Whitton, 1980; Janssens and Grigg, 1988). Glucocorticoids, like the cat- echolamines, are also involved in glucose regulation in many animals. In mammals, glucocorticoids inhibit glycogen breakdown and promote glycogen synthesis by increas- ing the activity of several enzymes involved in glycogen synthesis (Baxter, 1976; Beato and Doenecke, 1980). The role of glucocor- ticoids in glucose regulation in turtles is not 308 0016~6480/92 $1.50 Copyright 8 1992 by Academic Press, Inc. All rights of reproduction in any form reserved.