Document Detail

Monoaminergic changes associated with socially induced sex reversal in the saddleback wrasse.
MedLine Citation:
PMID:  12763086     Owner:  NLM     Status:  MEDLINE    
The process of sex reversal in fishes is socially mediated and requires a total reorganization of the hypothalamo-pituitary-gonadal axis. When the ratio of males to females in a population of saddleback wrasse (Thalassoma dupperrey) is too low, the largest female becomes male over the course of 6 to 8 weeks. This event requires the conversion of external social cues into internal chemical cues. In an attempt to investigate the role monoamines might play in this process, two females were housed together in floating enclosures in order to induce sex reversal in the larger. Brains were sampled at various time points throughout the process of sex reversal. Monoamines were measured in the amygdala, preoptic area, ventral hypothalamus, locus coeruleus and raphe nucleus. Changes were demonstrated in monoamine metabolism for all brain regions examined. The most important changes in monoamine-system activation were seen during the first week of sex reversal. It is during this time that transitional animals undergo behavioral sex reversal. There is an increase in serotonergic activity in the amygdala which is likely related to territorial acquisition. The absence of male aggression results in a less stressful environment for the female and a reduction in serotonergic activity in the preoptic area allowing for an increase in noradrenergic activity potentially triggering the reorganization of the reproductive axis. In the ventral hypothalamus, there is a decrease in noradrenergic and increase in dopaminergic activity associated with this change from female to male. The locus coeruleus shows an increase in noradrenergic activity later in the process of sex reversal which is probably a response to more circulating androgens. In the raphe nucleus, there is a decrease in serotonergic activity at the time of behavioral sex reversal. This decrease in serotonergic activity is linked to the behavioral component of sex reversal. This study suggests that monoamines play a very important role in both behavioral and gonadal sex reversal in the saddleback wrasse, the former under the control of serotonin in the raphe and the latter mediated via serotonergic effects on norepinephrine in the preoptic area.
E T Larson; D O Norris; C H Summers
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Neuroscience     Volume:  119     ISSN:  0306-4522     ISO Abbreviation:  Neuroscience     Publication Date:  2003  
Date Detail:
Created Date:  2003-05-23     Completed Date:  2003-07-28     Revised Date:  2011-12-06    
Medline Journal Info:
Nlm Unique ID:  7605074     Medline TA:  Neuroscience     Country:  United States    
Other Details:
Languages:  eng     Pagination:  251-63     Citation Subset:  IM    
Department of Environmental, Population, and Organismic Biology, Campus Box 334, University of Colorado, Boulder, CO 80309-0334, USA.
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MeSH Terms
3,4-Dihydroxyphenylacetic Acid / analysis
Biogenic Monoamines / analysis,  metabolism*
Brain / anatomy & histology,  metabolism*
Brain Chemistry
Hermaphroditic Organisms*
Hydroxyindoleacetic Acid / analysis
Interpersonal Relations*
Methoxyhydroxyphenylglycol / analysis
Sex Determination Processes*
Time Factors
Grant Support
1 F31 MN11595-01/MN/OMHHE CDC HHS
Reg. No./Substance:
0/Biogenic Monoamines; 102-32-9/3,4-Dihydroxyphenylacetic Acid; 534-82-7/Methoxyhydroxyphenylglycol; 54-16-0/Hydroxyindoleacetic Acid

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