Effects of activin A on anterior pituitary cells fractionated by centrifugal elutriation.
We have shown previously that activin A increases the number of immunoreactive follicle-stimulating hormone (FSH) cells. To further investigate the action of activin A, we examined its effects on anterior pituitary cells fractionated by centrifugal elutriation. Before activin A treatment, FSH cells were widely distributed among various fractions; a higher proportion of FSH cells was found in larger cell fractions (fractions 5-9), and a lower proportion in smaller cell fractions (fractions 2-4). After culture of the cells in each fraction with activin A (10 ng/ml) for 72 h, the number of FSH cells in fraction 4 only was significantly (P less than 0.05) higher by 225% than that in cells cultured without activin A. The amount of FSH secreted into the medium was minimal or undetectable in fractions 1-4. However, FSH secretion tended to be, or was significantly (P less than 0.01 in fraction 9), stimulated by activin A in fractions 5-9, in which the numbers of FSH cells were not significantly affected. These results suggest a dual mode of action of activin A on FSH: activin A increases the number of FSH cells in a specific type(s) of middle-sized cell fraction, and stimulates FSH secretion at least from larger cells without affecting the number of FSH cells.
Katayama
T
T
Department of Veterinary Physiology, University of Tokyo, Japan.
Shiota
K
K
Takahashi
M
M
D028341:Activins; D000818:Animals; D002458:Cell Fractionation; D002478:Cells, Cultured; D002498:Centrifugation; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology*; D007150:Immunohistochemistry; D007265:Inhibins / Q000494:pharmacology*; D008297:Male; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D006133:Growth Substances; D028341:Activins; D007265:Inhibins; D011388:Prolactin; D005640:Follicle Stimulating Hormone