Ethinylestradiol differentially interferes with IGF-I in liver and extrahepatic sites during development of male and female bony fish.
Growth and sexual development are closely interlinked in fish; however, no reports exist on potential effects of estrogen on the GH/IGF-I-axis in developing fish. We investigate whether estrogen exposure during early development affects growth and the IGF-I system, both at the systemic and tissue level. Tilapia were fed from 10 to 40 days post fertilization (DPF) with 17alpha-ethinylestradiol (EE(2)). At 50, 75, 90, and 165 DPF, length, weight, sex ratio, serum IGF-I (RIA), pituitary GH mRNA and IGF-I, and estrogen receptor alpha (ERalpha) mRNA in liver, gonads, brain, and gills (real-time PCR) were determined and the results correlated to those of in situ hybridization for IGF-I. Developmental exposure to EE(2) had persistent effects on sex ratio and growth. Serum IGF-I, hepatic IGF-I mRNA, and the number of IGF-I mRNA-containing hepatocytes were significantly decreased at 75 DPF, while liver ERalpha mRNA was significantly induced. At 75 DPF, a transient decline of IGF-I mRNA and a largely reduced number of IGF-I mRNA-containing neurons were observed in the female brain. In both sexes, pituitary GH mRNA was significantly suppressed. A transient downregulation of IGF-I mRNA occurred in ovaries (75 DPF) and testes (90 DPF). In agreement, in situ hybridization revealed less IGF-I mRNA signals in granulosa and germ cells. Our results show for the first time that developmental estrogen treatment impairs GH/IGF-I expression in fish, and that the effects persist. These long-lasting effects both seem to be exerted indirectly via inhibition of pituitary GH and directly by suppression of local IGF-I in organ-specific cells.
Shved
Natallia
N
Division of Neuroendocrinology, Institute of Anatomy, University of Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland.
Berishvili
Giorgi
G
D'Cotta
Helena
H
Baroiller
Jean-François
JF
Segner
Helmut
H
Eppler
Elisabeth
E
Reinecke
Manfred
M
D000375:Aging / Q000378:metabolism*; D000818:Animals; D049628:Body Size / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000235:genetics; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D005880:Gills / Q000378:metabolism; D013006:Growth Hormone / Q000235:genetics; D017403:In Situ Hybridization; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D010053:Ovary / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012744:Sex Ratio; D013737:Testis / Q000378:metabolism; D017210:Tilapia / Q000254:growth & development* / Q000378:metabolism*
D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D004997:Ethinyl Estradiol; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone