Saponin Effects of Prolactin-Like Stimulation of Ornithine Decarboxylase Activity in Mouse Mammary Gland Explants

Summary

Saponin, a naturally occurring plant glycoside, was found to elicit a prolactin-like stimulation of ornithine decarboxylase (ODC) activity in mouse mammary gland explants. A dose-response activation of ODC was observed with saponin at concentrations between 2 and 10 μg/ml. At concentrations of 10 and 15 μg/ml, saponin effected a response similar to that of PRL; when tested in concert, PRL and saponin caused a nonadditive response. The timecourse of the saponin and PRL effects on ODC activation were not different; a maximum response occurred 2-4 hours after addition of saponin. The saponin and PRL responses were abolished by antibiotics (puromycin and cyclohexamide) that inhibit protein synthesis, but not by actinomycin D which inhibits RNA synthesis. Finally, saponin, by itself, did not affect the rate of milk product formation, but at higher concentrations (above 0.5 μg/ml) impaired the PRL stimulation of lipid and casein synthesis.

Key words

Saponin - Prolactin - Mouse Mammary Glands - Ornithine Decarboxylase - Casein - Lipids