Induction of vitellogenin production in male tilapia ( Oreochromis mossambicus) by commercial fish diets

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2009-10, Vol.154 (2), p.249-254
• Main Authors: Davis, Lori K., Fox, Bradley K., Lim, Chhorn, Hiramatsu, Naoshi, Sullivan, Craig V., Hirano, Tetsuya, Grau, E. Gordon
• Format: Article
• Language: English
• Subjects: Animal Feed - adverse effects; Animal Feed - analysis; Animals; Aquaculture; Decapodiformes; Estradiol - administration & dosage; Estradiol - adverse effects; Estradiol - analysis; Estrogen; Estrogen Receptor alpha - genetics; Estrogen Receptor alpha - metabolism; Estrogen Receptor beta - genetics; Estrogen Receptor beta - metabolism; Estrogens - administration & dosage; Estrogens - adverse effects; Female; Fish diet; Fish Products - adverse effects; Fish Products - analysis; Fish Proteins - blood; Fish Proteins - genetics; Fish Proteins - metabolism; Fishmeal; Food Deprivation - physiology; Glycine max - chemistry; Gonadal Steroid Hormones - administration & dosage; Gonadal Steroid Hormones - adverse effects; Injections, Intraperitoneal; Liver - metabolism; Male; Oreochromis mossambicus; Statistics, Nonparametric; Teleostei; Tilapia; Tilapia - metabolism; Vegetables; Vitellogenin; Vitellogenins - blood; Vitellogenins - genetics; Vitellogenins - metabolism
• ISSN: 1095-6433; 1531-4332
• DOI: 10.1016/j.cbpa.2009.06.009

Mozambique tilapia, ( Oreochromis mossambicus), are a euryhaline teleost and an important biological model species. Captive male tilapia frequently have high levels of the estrogen-induced yolk precursor protein vitellogenin (Vg), a common indicator of exposure to estrogenic compounds. Sex steroids are found in commercial fish diets, but relatively few studies have examined the relationship between commercial diets and Vg production. In a fasting experiment to ascertain a dietary role in male Vg production, plasma Vg was reduced to negligible levels after 2 weeks of fasting, while no change in estrogen receptor (ER) expression was seen. When male tilapia were fed a squid-based diet that replaced the commercial trout diet, plasma Vg was reduced to undetectable levels over 40 days, concomitant with significant reductions in hepatic expression of Vgs A, B, and C, and ERβ, compared with control fish fed commercial trout diet. Female tilapia fed the squid-based for 20 days had no change in these parameters. When male tilapia were fed a defined, soy-based diet, plasma Vg reduced to 20% of levels in fish given either commercial trout diet or a defined, fishmeal-based diet. Overall, results from these studies suggest that estrogens in a commercial trout diet induce vitellogenin production by increasing expression of Vg, but not ER genes in male tilapia.