PROLACTIN-BINDING ACTIVITY OF BOVINE GRANULOSA CELLS ON LUTEINIZATION AND EXPOSURE TO
SOMATOTROPIN IN VITRO
I. Yu. Lebedeva,1 T. I. Kuzmina,1 V. A. Lebedev,1
F. Schneider,2 H. Aim,2 H. Tomer2
1 All-Russian Research Institute of Farm Animal Genetics and Breeding,
St. Petersburg-Pushkin, Russia, and
2 Research Institute for Biology of Farm Animals, Dummerstorf, Germany;
1 e-mail: irledv@mail.ru
The influence of luteinization and bovine somatotropin (ST, 5-50 ng/ml) during cultivation of bovine gra-nulosa cells on
their ability to bind [125I]-labeled bovine prolactin (PRL) was studied. On the second day of cultivation in serumfree medium,
granulosa cells from immature antral follicles underwent spontaneous luteinization, in both the absence and presence of ST. The level of
[125I]-PRL specific binding to cells increased after two days of cultivation, with a negative correlation being revealed
between estradiol production by the cells and their PRL-binding activity. At the same time, the addition of ST to the culture medium had
no effect on the level of [125I]-PRL specific binding to native and luteinizing granulosa cells. The findings suggest a
stimulatory influence of the luteal differentiation process on the PRL-binding activity of bovine granulosa cells, this influence is
independent of the action of ST.
Key words: prolactin, somatotropin, granulosa cells, luteinization, receptors
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