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
