Cichalsoma dimerus: a fish model for studying stress and social control of reproduction.

FELIPE ALONSO; MAXIMILIANO M. CÁNEPA; FABIANA LO NOSTRO; M. CRISTINA MAGGESE; MATIAS PANDOLFI

Mar del Plata

Encuentro; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Animal behaviour has an important role in brain physiology and reproduction. The presence of dominant conspecifics may produce a suppression of reproductive maturation in non-dominant individuals. The South American freshwater fish C. dimerus represents an interesting model for studying social control of reproduction at ethological, morphological, physiological and molecular levels. Adults of both sexes (Std. lenght 9.33±1.62 cm) were placed in neutral community tanks. The experiment was repeated 3 times. Four different kinds of social status were defined: Territorial-Dominant male (TDm), Reproductive Aggressive female (RAf), T noD (TND) and noT-noD (NTND) fish. Animals were sacrificed at the most aggressive period (6 days post hatching larvae from TDm and RAf couple); weighted and measured. Cortisol and testosterone concentrations were analyzed by RIA from plasma samples. Brains were fixed for performing IHC for GnRH neurons. Pituitary homogenates were used to estimate FSH, LH and SL content. Gonads were weighted and fixed to study their morphology in different social status. NTND showed 3 fold higher levels of cortisol, lower testosterone, FSH and SL levels. There were no differences in LH levels. NTND males had their testis full of sperm though espermiation could not take place. Future studies will focus on the neuro-electrophysiological and transcriptional level