Teleost Serotonin

Cross references:    Teleosts       Serotonin References    



INITIAL SUMMARIES
OF THE REFERENCES



Following are initial summaries of the references.  The references are designated by the first words of their title and their year of publication.   

The references themselves follow this list of their initial summaries. 


Roles ... 1993   
    "
The brain serotonergic system appears to inhibit aggression and spontaneous locomotor activity in both fish and mammals."   
    "
By contrast, the brain dopaminergic system appears to stimulate aggressive behaviour in both fish and mammals, and dominant fish show signs of elevated dopaminergic activity in telencephalon."  


Serotonin ... 1997   
    "
Socially subordinate fish display elevated plasma cortisol levels "  
    "In conclusion, the results from the present study show that 8-OH-DPAT elevates plasma cortisol in catheterized rainbow trout in a dose-dependent manner. The effect of 8-OHDPAT is most likely mediated by activation of 5-HT1A-like receptors, 8-OH-DPAT being a highly selective 5-HT1A receptor agonist."    



THE REFERENCES



Roles of brain monoamine neurotransmitters in agonistic behaviour and stress reactions, with particular reference to fish (Goog)  - 1993      
   
Only abstract available online.  This link doesn't always work, but if you type the title of the paper into Google, the abstract will come up.   
    "In fish as well as mammals, stress induces increased brain serotonergic activity, and a similar increase in serotonergic activity is seen in subordinate individuals in a dominance hierarchy.   
    The brain serotonergic system appears to inhibit aggression and spontaneous locomotor activity in both fish and mammals.
    Subordinate fish show several behavioural characteristics, notably inhibition of aggressive behaviour, low spontaneous locomotor activity and decreased food intake, that are likely to be related to their increased brain serotonergic activity.
    By contrast, the brain dopaminergic system appears to stimulate aggressive behaviour in both fish and mammals, and dominant fish show signs of elevated dopaminergic activity in telencephalon.
    The similarities between fish and mammalian monoaminergic functions suggest that these are phylogenetically very old mechanisms that have been conserved during the last 400 million years of vertebrate evolution.
"    


Serotonin as a regulator of hypothalamic-pituitary interrenal activity in teleost fish (PubMed)   - 1997   
Full length PDF available online for free. 
    However, brain 5-HT could also play an important role in the regulation of the HPI axis. Socially subordinate fish display elevated plasma cortisol levels [10], and increased interrenal cell sizes, suggesting a chronic activation of the HPI axis [19]." 
My comment #1
Their data certainly shows the injection of a 5-HT1A agonist causing an increase in circulating cortisol.  Therefore, for this to be a negative feedback loop, an increase in cortisol must cause a decrease in 5-HT at the 5-HT1A receptor. 
    "In conclusion, the results from the present study show that 8-OH-DPAT elevates plasma cortisol in catheterized rainbow trout in a dose-dependent manner. The effect of 8-OHDPAT is most likely mediated by activation of 5-HT1A-like receptors, 8-OH-DPAT being a highly selective 5-HT1A receptor agonist. This conclusion is further supported by the fact that previous results clearly show that 5-HT1A-like receptors are present in the brain of salmonid fish. However, at the present time, we do not know at which level of the HPI axis 8-OH-DPAT exerts its effect."
My comment #2:  
    Injecting a 5-HT1A agonist into the dorsal aorta may have flooded the pituitary in an unnatural way.   









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