Effect of activin on production and secretion of prolactin and growth hormone in cultured rat GH3 cells.
OBJECTIVE
To evaluate the effect of the growth factor activin A on the secretion of prolactin (PRL) and GH in cultured GH3 cells.


METHODS
The concentrations of PRL and GH secreted from GH3 cells cultured in media with and without activin A were measured by RIA, and the expression of PRL mRNA and GH mRNA were analyzed using the Northern blot method.


RESULTS
Activin A significantly inhibited PRL release from GH3 cells cultured for 48h in a dose-dependent manner (activin: 0.3-3nM). The inhibitory effects of 3nM activin A were observed in the culture from 12h to 48h (53.2% of control). Activin A (3nM) also significantly inhibited the expression of PRL mRNA at 24h (33.8% of control). In contrast, activin A significantly stimulated GH release from GH3 cells cultured for 48h in a dose-dependent manner (activin: 0.3-3nM). The stimulatory effect of 3nM activin A was observed in the culture for 48h (157.6% of control). Activin A (3nM) also significantly stimulated the expression of GH mRNA at 24h (183.6% of control). In spite of these significant changes in PRL and GH secretion, pit-1 mRNA levels were not significantly changed by activin A.


CONCLUSIONS
These findings indicated that activin A modulates PRL and GH secretion through the regulation of PRL and GH gene transcription in GH3 cells, but that these effects are unrelated to pit-1 gene expression.
Tamura
N
N
Department of Obstetrics and Gynecology, School of Medicine, University of Tokushima, Tokushima, 770-8503 Japan. noriko@shikoku.ne.jp
Irahara
M
M
Kuwahara
A
A
Ushigoe
K
K
Sugino
H
H
Aono
T
T
D028341:Activins; D000818:Animals; D015152:Blotting, Northern; D015870:Gene Expression; D013006:Growth Hormone / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D007265:Inhibins / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011388:Prolactin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D011863:Radioimmunoassay; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D028341:Activins; D007265:Inhibins; D011388:Prolactin; D013006:Growth Hormone