The Stimulatory Effect of Activin on PRL Production in GH3 Cells in a Serum-Free Culture

Background and Aims: Activin was originally found as a stimulating factor of follicle stimulating hormone in pituitary cell cultures. To establish a simple culture system for studying the effects of activin on prolactin production, we examined the effects of activin in rat somatolactotroph derived GH3 cells cultured in a serum free condition. Methods: GH3 cells were cultured in Ham’s F10 medium containing 2 mM L-glutamine and 0.1％ (w/v) BSA with activin, follistatin (an activin binding protein), or a vehicle (control). Results: The cell viability was between 80 to 90％ throughout the 96 hour incubation period in the three groups. Activin stimulated prolactin production in a time dependent (24-96 hours)and dose dependent (75-300 ng/ml)manner. A co-treatment with graded doses of follistatin and 100 ng/ml of activin suppressed the increase of prolactin production brought about by activin in a dose dependent manner, and the production decreased to the control level after the addition of 300 ng/ml of follistatin. Conclusions: The present study demonstrated the stimulatory effect of activin on prolactin production and the antagonism between activin and follistatin in GH3 cells in a serum free condition. This culture system is thus useful to study the effects of activin on prolactin production