Effects of progesterone and estradiol on the reproductive axis in immature diploid and triploid rainbow trout.
2003
Atteke, Christiane | Vetillard, Angélique | Fostier, Alexis | Garnier, Danièle-Hélène | Jego, Patrick | Bailhache, Thierry | Interactions cellulaires et moléculaires (ICM) ; Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS) | Station commune de Recherches en Ichtyophysiologie, Biodiversité et Environnement (SCRIBE) ; Institut National de la Recherche Agronomique (INRA) | Groupe d'étude de la reproduction chez le mâle (GERM) ; Université de Rennes (UR)-Institut National de la Santé et de la Recherche Médicale (INSERM)-IFR98
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Mostrar más [+] Menos [-]Inglés. In fish species, many studies demonstrated the crucial role of estradiol (E2) in the development of the reproductive axis, but progesterone (P) has been described mainly as a precursor steroid and no clear role by itself has been reported. Moreover, a cooperative effect of P (or another progestin) and E2 in fish has never been reported to our knowledge. In the present work, we investigated the effects of P, alone or in combination with E2, on the reproductive-axis of immature rainbow trout (Oncorhynchus mykiss). Liver vitellogenin and estradiol receptor (rtER) mRNA levels increased after E2 treatment, but were unchanged by P treatments as a reflection of peripheral action of steroids. In contrast, at the pituitary level, LH contents increased after E2 and/or P treatments. Focusing on the brain level, we confirmed a clear up regulation of rtER expression by E2 in sterile triploid females, and we also demonstrated a similar stimulating effect of P alone but no cooperative effect together with E2. In conclusion, our data demonstrate that in immature trout, prior to the beginning of the first reproductive cycle, unlike E2, P is able to stimulate the reproductive brain-pituitary axis without affecting vitellogenin synthesis in the liver.
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