Effects of TRH on cell proliferation of rat pituitary cells (GH3) |
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Authors: | Yukiko Yajima Toshikazu Saito |
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Institution: | (1) the Department of Hormone Research, The Tokyo Metropolitan Institute of Medical Science, 3-18, Honkomagome, Bunkyoku, 113 Tokyo, Japan;(2) Division of Endocrinology and Metabolism, Jichi Medical School, 329-04 Tochigiken, Japan |
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Abstract: | Summary Chronic treatment (more than 3 d) of GH3 cells, cloned rat pituitary cells producing prolactin, with 100 nM TRH resulted in a 41% reduction in the rate of cell growth in a medium containing 0.5% fetal bovine serum. These effects
of TRH appeared both in the medium containing a higher concentration of serum and in that containing six growth factors, i.e.
insulin, transferrin, parathyroid hormone, fibroblast growth factor, triiodothyronine, and multiplication-stimulating activity
(MSA) instead of serum. TRH stimulated prolactin production by GH3 cells in a dose-dependent manner both in the serum-supplemented and serum-free media. On the other hand, TRH, at 1 nM, elicited a 130% stimulation in the cellular growth, whereas, at concentrations of more than 10 nM, it inhibited the growth significantly.
In the defined culture system, it was demonstrated that TRH stimulated prolactin production in the presence or absence of
six growth factors, whereas its inhibitory effects on cellular growth appeared only in the presence of MSA regardless of the
presence or absence of the other five factors. Furthermore, it was shown that a dose-dependent stimulatory effect of MSA on
the growth of GH3 cells was suppressed by TRH. TRH exhibited only a stimulatory effect on cellular growth in the medium containing the five
factors other than MSA. In conclusion, TRH could inhibit cell growth of GH3 in the presence of MSA in the defined medium or MSA-like factor(s) in the serum-supplemented medium. |
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Keywords: | rat pituitary cells growth TRH serum MSA |
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