Title: Influence of Temperature Stress and Cortisol on Plasma Insulin-Like Growth Factor-I in Sunshine Bass Author
Submitted to: Comparative Endocrinology International Congress Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 24, 2005
Publication Date: May 22, 2005
Citation: Davis Jr, K.B. 2005. Influence of temperature stress and cortisol on plasma insulin-like growth factor-i in sunshine bass [abstract]. Comparative Endocrinology International Congress Abstracts (Final Program). p. 62. Technical Abstract: Hormonal regulation of growth in fish includes the pituitary-hepatic-somatic axis. Growth hormone from the pituitary stimulates the liver to produce insulin-like growth factors-I and -II. Insulin-like growth factor-I (IGF-I) is presently thought to be the primary factor which stimulates somatic growth in fish. Sunshine bass is a hybrid produced by crossing a female white bass with a male striped bass and is an important emerging fish used in aquaculture. The environmental factors which affect plasma concentration of IGF-I are only beginning to be understood. This study examined the effect of several environmental conditions on plasma IGF-I levels in sunshine bass. Fish acclimated to 25 and 30 0C had higher plasma IGF-I concentrations than fish acclimated to 5, 10, 15, or 20 0C. When fish acclimated to 25 or 30 0C were stressed by confinement for 15 minutes, plasma IGF-I concentrations were significantly below non-stressed fish, 2 hours after the end of the stress. When fish were fed feed with 100 or 200 mg cortisol per kg feed peak plasma cortisol occurred 2 hours after feeding and fell during the next 12 hours. Peak plasma glucose occurred 6 hours after feeding, however plasma IGF-I was not changed by feeding either level of cortisol. Temperature appears to affect IGF-I concentrations and confinement stress decreases IGF-I concentrations. However, the decrease in IGF-I concentration following stress does not appear to be mediated by cortisol.