Endocrine regulation of pejerrey (Odontesthes bonariensis) oogenesis. Influence of environmental cues on its natural reproductive cycle.

ELISIO M; CHALDE T; MIRANDA LA

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART B, BIOCHEMISTRY & MOLECULAR BIOLOGY.

ELSEVIER SCIENCE INC

Lugar: Amsterdam; Año: 2014 vol. 175 p. 102 - 109

1096-4959

The goal of this study was to evaluate the essential components controlling the brain-pituitary-gonad axis during pejerrey (Odontesthes bonariensis) oogenesis in the wild. Ovarian developmental stages from vitellogenesis up to ovulation were associated with increasing daylength and water temperatures below to 21 ºC (winter and beginning of spring). Gonadal regression was observed when water temperature exceeded this value or when photoperiod decreased. Most females were arrested at primary growth stage during summer (high temperature) or at cortical alveoli stage between autumn and beginning of winter (short photoperiod). Plasma E2 and transcript levels of fshr, cyp19a1b and cyp19a1a increased during vitellogenesis, while fshb remained high at all vitellogenic stages. A significant correlation between plasma sex steroids (T and E2) and cyp19a1b as well as lhcgr transcript levels was observed during vitellogenesis, suggesting a steroid positive feedback. Gnrh-I, Gth subunits and lhcgr transcript levels increased significantly during late vitellogenesis and final maturation. Present results suggest that pejerrey vitellogenesis is controlled by Fsh/Fshr, stimulating gonadal aromatase and estradiol synthesis. Moreover, the increase of testosterone and estradiol during final vitellogenesis could induce coordinately the functioning of the Gnrh/Lh system (perhaps through brain P450 aromatase stimulation and brain estradiol increase) and the gonadal Lhcgr synthesis to promote the final maturation of oocytes. All these stimulation mechanisms of gonadal development would be possible only under permissive environmental conditions.