Cortisol is the principal corticosteriod in teleost fishes and its plasma concentrations rise dramatically during stress. The relationship between this cortisol increase and its metabolic consequences are subject to extensive debate. Much of this debate arises from the different responses of the many species used, the diversity of approaches to manipulate cortisol levels, and the sampling techniques and duration. Given the extreme differences in experimental approach, it is not surprising that inconsistencies exist within the literature. This review attempts to delineate common themes on the physiological and metabolic roles of cortisol in teleost fishes and to suggest new approaches that might overcome some of the inconsistencies on the role of this multifaceted hormone. We detail the dynamics of cortisol, especially the exogenous and endogenous factors modulating production, clearance and tissue availability of the hormone. We focus on the mechanisms of action, the biochemical and physiological impact, and the interaction with other hormones so as to provide a conceptual framework for cortisol under resting and/or stressed states. Interpretation of interactions between cortisol and other glucoregulatory hormones is hampered by the absence of adequate hormone quantification, resulting in correlative rather than causal relationships.

Cortisol in teleosts: dynamics, mechanisms of action, and metabolic regulation

Physiological changes in fish from stress in aquaculture with emphasis on the response and effects of corticosteroids

Androgens in teleost fishes

Publisher Summary This chapter discusses the functional morphology of teleost gonads. Information presented in this chapter indicates that there are several processes of germ cell development, which are closely associated with changes in cellular activities of somatic cell elements. Recent studies on biochemical aspects of vitellogenesis in teleosts have shown that the hepatic and ovarian yolk proteins are similar to those of amphibian species. An in vitro method involving the separation of the follicular components has facilitated investigations of the detailed mechanism of the production of two major follicular steroid hormones. As a result of the usage of this technique, a two cell-type model involving thecal and granulosa cell layers has been proposed for the production of these two steroids for the first time in lower vertebrates. With further refinements this well characterized incubation procedure should provide an excellent system for studying the molecular basis of the mechanism of gonadotropin action on follicular steroidogenesis.

6 The Functional Morphology of Teleost Gonads

The olfactory hypothesis of the salmonids' homing assumes that the juvenile is conditioned to recognize a specific scent of its native river during the smolt stage and that it uses this characteristic to locate its river for upstream migration. We tested this hypothesis and exposed, in artificial conditions, some farmed coho salmon, rainbow trout and fario trout, aged 18 months, to a chemical (morpholine or alcoolphenetyl) introduced in the natural production environment (mixed with the scents of the native river), in order to determine if they will be responsive to this product to locate their initial production environment during upstream migration.

Olfactory imprinting and homing in salmon

Identification and quantification of the major androgens in testicular and peripheral plasma of Atlantic salmon (Salmo salar) during sexual maturation

A new blood steroid, 11-ketotestosterone, has been isolated from postspawned male sockeye salmon. The steroid was identified by chromatography, infrared spectra, chemical transformation, and synthe...

Isolation and identification of 11-ketotestosterone in salmon plasma.

Effects of corticosteroids on liver transaminases in two salmonids, the rainbow trout (Salmo gairdnerii) and the brook trout (Salvelinus fontinalis).

Cortisone, cortisol, and 17-hydroxyprogesterone were isolated from the plasma of prespawning Fraser River sockeye salmon. The female plasma contained double the concentration of cortisone and cortisol found in male plasma, 41 μg and 26 μg/100 ml respectively as compared with 22 μg and 11 μg/100 ml.Corticosterone is probably present at a very low concentration and neither 11-desoxycorticosterone nor aldosterone was detected in the plasma from approximately 100 fish. Cortisone, cortisol, and total 17-hydroxysteroids were quantitatively determined in plasma samples obtained from two pure races of sockeye captured at various stages of sexual maturity. The combined concentration of cortisone and cortisol which, at the mouth of the river was three times that of the normal human, increased to as high as 17 times this level following spawning. The results are discussed in relation to the death of the fish.

Biochemical studies on sockeye salmon during spawning migration: vii. steroid hormones in plasma

Non-frozen storage of sperm for several weeks was achieved by the use of buffered protective agents and low temperature For example, sperm stored with 5% dimethyl sulphoxide at −45 C for 28 days 

D. R. Idler

Papers

Identification and quantification of the major androgens in testicular and peripheral plasma of Atlantic salmon (Salmo salar) during sexual maturation

Isolation and identification of 11-ketotestosterone in salmon plasma.

Effects of corticosteroids on liver transaminases in two salmonids, the rainbow trout (Salmo gairdnerii) and the brook trout (Salvelinus fontinalis).

Biochemical studies on sockeye salmon during spawning migration: vii. steroid hormones in plasma

Sub-Zero Preservation of Atlantic Salmon Sperm