REGULATION OF CELL-PROLIFERATION AND ESTROGEN SYNTHESIS BY OVINE LH, IGF-I, AND EGF IN THECA INTERSTITIAL-CELLS OF THE DOMESTIC HEN CULTURED IN DEFINED MEDIA

There is relatively little information on the factors which regulate the proliferation and alterations in the steroidogenic capacity of avian theca cells during follicular maturation. The development of culture conditions for these cells to determine the effects of gonadotrophin (LH) and the growth factors epidermal growth factor (EGF) and insulin-like growth factor-I (IGF-I) on DNA synthesis and estrogen production is reported. Cultures were established in serum-supplemented (with fetal calf serum or chicken serum) or ITS+ (insulin, transferrin, and selenium plus additives) supplemented serum-free media. Cell replication occurred throughout the 72-hr culture period as indicated by a linear increase in the DNA content of the culture dishes. Aromatase activity of the cells as defined by conversion of androstenedione to estrogen was best maintained in serum-free medium while sera inhibited this activity. Ovine LH enhanced the aromatase activity of cultured cells from medium and small-sized follicles, while IGF-I and EGF inhibited both basal and LH-stimulated aromatase activity. LH, IGF-I, and EGF all stimulated cell proliferation as reflected by increased DNA. The responses of cells to these peptides varied with the size of the follicle, with the greatest effects on cells from F4/5. (c) 1994 Academic Press, Inc.