Aggressive behavior and reproductive physiology in females of the social cichlid fish Cichlasoma dimerus

TUBERT, C.; LO NOSTRO, F.; PANDOLFI, M.

Huerta Grande, Cordoba

Encuentro; 2da. Reunión Conjunta de Sociedades de Neurociencias; 2010

Circulating androgens are potent mediators of male and female aggressive behavior. Aggression and androgen levels have been strongly associated with dominance over conspecifics. The GnRH-3 neuronal population is located in the olfactory bulb of several vertebrate species and it is not related with gonadotropin release but with reproductive behavior. We studied the body coloration pattern and described and quantified the aggressive and reproductive behavior of adult females of C. dimerus during four stages of the reproductive phase: prespawning, spawning, larvae hatching stage and free-swimming larva stage. To study the physiology of the brain-pituitary-gonadal axe in these four stages, adult couples (N=16) were kept under constant temperature and a 14:10 hs photoperiod. Females were weighted and measured; blood was extracted to measure androgens, 17-β estradiol and cortisol by RIA. Liver, spleen and gonadosomatic index were also calculated. We study the histomorphology of the ovaries. The GnRH-3 neural population was studied by IHC and morphometrical analysis. Results showed that prespawning is the most aggresive stage; androgen and estradiol levels are maximum also in the prespawning stage, and cortisol levels are maximum in spawning stage. GSI are maximum in prespawning stage, and minimum in spawning. LSI showed no differences between stages. Taken together these results suggests that GnRH-3 may regulate the reproductive physiology and behavior of C. dimerus, and androgens are involved in the aggressive behavior of females of these species.