Does ovarian granulosa and theca cell interaction in co-culture affect the cytoplasmic microtubule organization?

Theca (T) cells modulate steroid secretion by granulosa (G) cells in vitro. This investigation was undertaken to see whether the cytoskeleton is involved in this process. Monocultures of G cells alone, T cells alone and GT co-cultures were viewed by light microscopy. Microtubules were visualized using monoclonal Ab against tubulin. The specificity of the Ab was checked by Western blotting. One group of cells was treated with colchicine, a microtubule disrupting drug, to show its influence on oestradiol secretion by cultured cells. Microtubule arrangement was monitored using a fluorescence microscope. In monoculture of G cells a diffuse pattern of immunocytochemical staining of tubulin was noted while in T cells cultured alone the microtubule were arranged in a network of delicate fibres. In co-culture the microtubule arrangement changed in G cells and became very fine and less numerous than in theca fibres. Oestradiol secretion by colchicine-treated cultures different from control secretions. The E2 secretion declined in cultures of G cells (48.9 pg/10(5) cells in control vs 19.4 pg/10(5) cells in colchicine cells), and in T cells cultures alone (490 pg i n control vs 171 pg/10(5) cells in colchicine treated cells) while in co-culture a dose-dependent increase of this steroid was detected after the addition of colchicine (2,008 pg vs 1,269 pg/10(5) cells in control). It is conceivable that microtubules affect transport of androgens from their production site in T cells to G cells where this substrate is aromatized resulting in increased preovulatory oestradiol secretion.