Bovine Thecal Cells Secrete Transforming Growth Factor α and β
The objective of the present study was to determine if the peptides secreted by bovine thecal cells influenced the growth and differentiation of bovine granulosa cells. Bovine thecal cells were cultured under serum-free conditions, the conditioned medium was concentrated and the peptides fractionated on a Bio-Gel P-60 column in 1.0 M acetic acid. Fractions were tested for their ability to stimulate [3H]thymidine incorporation into bovine granulosa cell DNA. Growth-promoting activity was located in the 6,000–9,000 and the 16,000 molecular weight fractions. The peak fractions inhibited FSH-induced aromatase activity in rat granulosa cells, indicating the presence of TGFα-like peptides. A growth inhibitory activity was observed in fractions with a molecular weight of approximately 25,000. The inhibitory activity had the molecular weight of TGFβ, and TGFβ was found to inhibit [3H]thymidine incorporation into bovine granulosa cell DNA. The presence of TGFβ-like activity was confirmed in two independent bioassays; stimulation of FSH-induced aromatase activity, and increased [3H]thymidine incorporation into rat granulosa cell DNA in the presence of FSH. In summary, bovine thecal cells secrete TGFα- and TGFβ-like activities that have opposing actions on the growth of bovine granulosa cells. The relative amounts of these growth factors may determine the rate of growth of granulosa cells during follicular development.
KeywordsGranulosa Cell Thymidine Incorporation Follicular Development Aromatase Activity Thecal Cell
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- 1.Lussier J, Dufour JJ, Matton P. Growth rates of follicles in the bovine ovary [Abstract]. J Anim Sci 1983; 57(suppl 1):353.Google Scholar
- 2.Dorrington JH, McKeracher H, Garzo G, Skinner MK. Granulosa cell-theca cell interactions during follicular development. In: Labrie F, Proulx L, eds. Endocrinology. Amsterdam: Elsevier Science Publishers B.V., 1984:807–10.Google Scholar
- 4.Adashi EY, Resnick CE. Antagonistic interactions of transforming growth factors in the regulation of granulosa cell differentiation. Endocrinology 1986; 1879–81.Google Scholar
- 8.Lobb DK, Bendell JJ, Dorrington JH. Bovine thecal cells secrete a growth factor which stimulates granulosa cell proliferation [Abstract]. Biol Reprod 1986; 34(1):78.Google Scholar
- 11.Dorrington JH, Chuma AV, Bendell JJ. Transforming growth factor ß and follicle-stimulating hormone promote rat granulosa cell proliferation. Endocrinology 1988 (in press).Google Scholar
- 15.Lobb DK, Kobrin MS, Kudlow JE, Dorrington JH (in preparation).Google Scholar