Teleost Cortisol

Cross references:     Fish   Osteichthyes (Bony Fish)    Teleosts 
Teleost Hormones    Glucocorticoids  Teleost Dominance Hierarchies   

Survey of the adrenal homolog in teleosts. 

Only the abstract is available online, which may be just as well, since the full length article is 98 pages long.  
The adrenal homolog of teleosts is not a compact organ as the adrenal glands of most vertebrates but is composed by aminergic chromaffin and interrenal steroidogenic cells located mostly inside the head kidney that, in this taxon, generally has a hematopoietic function. The two tissues can be mixed, adjacent, or completely separated and line the endothelium of the venous vessels or are located in close proximity. The chromaffin cells in some species are also present in the posterior kidney. Histological and ultrastructural work revealed cytological peculiarities of both types of cells as compared to those of other vertebrate species. In particular, the interrenal ones can show some variations in ultrastructure depending on sex, time of the year, and relation to stress events. A periodic renewal of the whole gland tissue is also sustained by some studies. Research regarding development is scanty as compared to mammals and most studies go back to the early years of the past century.  
    The adrenal homolog of teleosts is under hormonal and neuronal control. Moreover, local paracrine interactions may play an important role in modulating a system involved in stress response and osmoregulation. Most previous studies involved a few species with the object of intensive rearing for commercial purposes; in fact cortisol, the main hormone secreted by the interrenal cells, can also influence reproduction and growth."  

The effects of cortisol administration on social status and brain monoaminergic activity in rainbow trout   
Full length article online for free. 
from the Abstract:   
The hypothesis that circulating cortisol levels influence the outcome of social interactions in rainbow trout was tested. Juvenile rainbow trout Oncorhynchus mykiss were given a single intraperitoneal (i.p.) implant containing either cortisol (110 mg kg–1 fish), or cortisol plus the glucocorticoid receptor antagonist RU486 (mifepristone; 1100 mg kg–1 fish), and sampled after 5 days of social interactions with either a similar sized (<1.5% difference in fork length) or smaller conspecific (>5% difference).  
    Within size-matched pairs of fish, cortisol treatment significantly increased the probability that the treated fish within each pair became subordinate, an effect that was abolished by simultaneous administration of RU486. Cortisol treatment also reduced the usual success of the larger fish within a pair to preferentially become dominant from 86% to 40% of pairs."   
    "Significant increases of serotonergic activity ([5-HIAA]/[5-HT] ratio) were detected in the telencephalon with cortisol treatment, an effect that was eliminated by simultaneous administration of RU486. Also, cortisol treatment significantly decreased dopaminergic activity in the telencephalon. Somewhat surprisingly, the effects of cortisol treatment on monoaminergic activity in the hypothalamus were opposite to those in the telencephalon. Moreover, in no case did administration of RU486 abolish these effects.  
    These results suggest that the effects of cortisol on social status in rainbow trout may be mediated via the modulation of central signaling systems and subsequent changes in behaviour and/or competitive ability, although the exact site of action in the brain remains uncertain. "      

Cortisol (Wiki) 
     "Cortisol, also known as hydrocortisone, is a steroid hormone or glucocorticoid produced by the adrenal gland.[1] It is released in response to stress, and to a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis, suppress the immune system, and aid in fat, protein and carbohydrate metabolism.

    "Cortisol (or hydrocortisone) is the most important human glucocorticoid. It is essential for life, and it regulates or supports a variety of important cardiovascular, metabolic, immunologic, and homeostatic functions. Glucocorticoid receptors are found in the cells of almost all vertebrate tissues."  

Glucocorticoid (Wiki) 
    "Glucocorticoids (GC) are a class of steroid hormones that bind to the glucocorticoid receptor (GR)...