Abstract
Primary cultures of tilapia (Oreochromis mossambicus) hepatocytes were developed and effects of several hormones on in vitro production of female-specific proteins (vitellogenin; VTG) were investigated. The hepatocytes were maintained for more than 2 weeks in Leibovitz-15 medium without the addition of any serum components. Absence of insulin in the culture media did not affect either cell attachment or monolayer formation. When VTG levels in the culture media were measured by an enzyme-linked immunosorbent assay (ELISA) using antibody against tilapia egg homogenate (a-E), VTG was detected in the medium for at least 8 days from hepatocytes isolated from a vitellogenic female but not from a male fish. However, the addition of estradiol-17β (E2) to the media of hepatocyte cultures from the male tilapia resulted in the elevation of VTG. Insulin and ovine growth hormone treatments did not have a significant effect on VTG induction. These results suggest that E2 is a major steroid hormone to induce VTG synthesis in the tilapia hepatocytes and that involvement of other hormones in the vitellogenic process is different among teleost species.
