Brain aromatase: Relationship to aggressive behavior in a Southamerican cichlid fish.

MARTÍN RAMALLO; GUSTAVO M. SOMOZA; MATÍAS PANDOLFI

Buenos Aires

Congreso; 7th International Symposium on Fish Endocrinology.; 2012

Teleost fish represent a unique model for the study of the relationship between brainestrogens and behavior. Every known kind of social system has evolved in fish, frommonogamy to sex-changing. Teleost, unlike any other vertebrate group, posseses twoaromatase enzyme genes: cyp19a1b which codes for the brain aromatase, whereascyp19a1a codes for the gonadal aromatase. As a part of an initial characterization ofthe brain estrogen system in the Southamerican cichlid fish ?chanchita?, Cichlasomadimerus, (a) simple and double immunohistochemestries were performed toanalyze brain aromatase localization, (b) brain aromatase expression distributionacross different organs was analyzed by PCR, (c) changes in brain aromatase proteinlevels in whole brain extracts were studied by Western blot in males of differentsocial status: dominant vs. submissive. Brain aromatase positive cells were radialglial cells mainly located in forebrain regions (primarily in the preoptic area andhypothalamus). Expression of brain aromatase gene was mainly found in brain andpituitary. Finally, submissive males showed higher brain aromatase protein levelsthan dominant males. Thus in C. dimerus, brain aromatase appears to be mainlypresent within the brain and its protein levels are socially regulated.