Activin A increases the number of follicle-stimulating hormone cells in anterior pituitary cultures.
The mode of action of activin A on the anterior pituitary gland (AP) was investigated using primary cultured cells. The AP cells were cultured with activin A (1 ng/ml) at various cell densities for 24-96 h, and further incubated for 3 h with activin A-free medium. When the cells were pretreated with activin A for 48 h, follicle-stimulating hormone (FSH) secretion during the following 3-h incubation was increased only at a density of 1 x 10(5) cells/200 mm2, but not at 2 x 10(5) or 4 x 10(5) cells/200 mm2. A longer pretreatment (96 h) was required in order to induce this response at a density of 2 x 10(5) cells/200 mm2. Luteinizing hormone (LH) secretion was not affected by activin A. Thus, the FSH secretory activity of the primary culture of AP was stimulated by activin A in a cell density-dependent manner. Furthermore, it was found that treatment with activin A (10 ng/ml) for 72 h increased the number of immunoreactive FSH cells by 25-41%, and that these newly induced FSH cells were low responders to gonadotropin-releasing hormone stimulation. The proportions of immunoreactive LH, thyroid-stimulating hormone, prolactin or growth hormone cells were not affected. From these results, we conclude that activin A increases FSH secretion by changing the cell population of pituitary gonadotropes.
Katayama
T
T
Department of Veterinary Physiology, Veterinary Medical Science, University of Tokyo, Japan.
Shiota
K
K
Takahashi
M
M
D028341:Activins; D000818:Animals; D002452:Cell Count; D002478:Cells, Cultured; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007265:Inhibins / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism; D008297:Male; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D028341:Activins; D007987:Gonadotropin-Releasing Hormone; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone