Vol. 283, Issue 3, C673-C678, September 2002
Hormonal mechanisms regulating hepatic vitellogenin synthesis
in the gilthead sea bream, Sparus aurata
G.
Mosconi1,
O.
Carnevali2,
H.
R.
Habibi3,
R.
Sanyal3, and
A. M.
Polzonetti-Magni1
1 Dipartimento di Scienze Morfologiche e Biochimiche
Comparate, Università degli Studi di Camerino, 62032 Camerino
(MC) Italy; 2 Istituto di Scienze del
Mare, Università di Ancona, 60131 Ancona, Italy; and
3 Department of Biological Sciences, University of
Calgary, Calgary, Alberta, Canada T2N 1N4
Experiments were carried out to study in
vitro the effects of 17
-estradiol (E2), homologous
pituitary homogenate (HPH), and recombinant red sea bream growth
hormone (sbGH) on vitellogenin (VTG) secretion from cultured sea bream
liver fragments. Basal secretion of VTG was found to be significantly
higher in the prespawning period, compared with sea bream liver in the
spawning and postspawning periods. Similarly, the sea bream liver
obtained during the prespawning period responded more significantly to
treatments with E2, HPH, or sbGH compared with sea bream
liver during spawning. In the postspawning period, treatments with
E2, HPH, or sbGH were without significant effect on VTG
secretion level in sea bream liver. The level of E2
receptors was also analyzed by Western blot analysis. The result
demonstrates a significantly higher level of E2 receptors in the sea bream liver at the prespawning stage compared with those at
the spawning and postspawning stages. The findings support the
hypothesis that homologous upregulation of estrogen receptors plays an
important role in the estrogen-sensitive control of VTG synthesis in
the sea bream liver.
vitellogenin induction; hormones; estradiol receptor
