Endocrine regulation of pejerrey (Odontesthes bonariensis) ovarian maturation throughout natural reproductive cycle

ELISIO, MARIANO; CHALDE TOMÁS; MIRANDA LEANDRO A.

Buenos Aires

Simposio; 7th International Symposium on Fish Endocrinology - 7ISFE; 2012

Comité Internacional

Fish reproduction regulation is a complex process involving the brain-pituitary-gonad axis and environmental cues. In this work, it was studied pejerey ovarian maturation in correlation with the expression of related genes and sex hormones throughout natural reproductive cycle. Primary growth stages were mainly found when day-length was maximum and at high water temperature (summer) meanwhile cortical alveoli and the beginning of vitellogenesis stages were observed when water temperature and day-length decreased (autumn-winter). A major number of ovulated females were found when the temperature and day length increased (end of winter-spring) with water temperature below 21° C. Above this temperature atretic females were found. Low levels of sexual steroids and gene expression were associated with previtelogenic and atretic stages. On the other hand, FSH-R, cyp19a1b, cyp19a1a and estradiol (E2) plasma levels were increasing during vitellogenesis, meanwhile FSH-β expression remained high in all vitellogenic stages. GnRH-I, GtHs and LH-R showed a significant increase during late vitellogenesis and final maturation. These results suggested that pejerrey vitellogenesis is controlled by FSH, stimulating aromatase and E2 synthesis, while final maturation is related with LH stimulation.