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

MARIANO ELISIO; TOMÁS CHALDE; LEANDRO ANDRÉS MIRANDA

Buenos Aires

Simposio; 7th International Symposium on Fish Endocrinology; 2012

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 GnRHs, GtHs, GtH-Rs, cyp19a1b, cyp19a1a genes and E2 plasmatic levels throughout natural reproductive cycle. Primary growth stages were found when the day-length and water temperature were maximum (summer) while 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 again (end of winter-spring) with temperature below 21° C. Above this temperature atretic females were found. Low levels of E2 and gene expression were associated with previtelogenic and atretic stages. On the other hand, FSH-R, cyp19a1b, cyp19a1a and E2 levels were increasing during vitellogenesis, while 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.