Journal of Reproduction and Development
Online ISSN : 1348-4400
Print ISSN : 0916-8818
ISSN-L : 0916-8818
Original Article
Involvement of GPR4 in increased growth hormone and prolactin expressions by extracellular acidification in MtT/S cells
Shiori MUSHASaishu YOSHIDASyo MURAKAMIRyotaro KOJIMAMasahito DEAINaoshi SASOChihiro MOGIKoichi SATOFumikazu OKAJIMAHideaki TOMURA
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JOURNALS OPEN ACCESS

2020 Volume 66 Issue 2 Pages 175-180

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Abstract

Hormone-secreting pituitary adenomas show unregulated hormonal hypersecretion and cause hyperpituitarism. However, the mechanism of the unregulated hormone production and secretion has not yet been fully elucidated. Solid tumors show reduced extracellular pH, partly due to lactate secretion from anaerobic glycolysis. It is known that extracellular acidification affects hormone secretion. However, whether and how the extracellular acidification influences the unregulated hormone production and secretion remain unknown. In the present study, we found that GPR4, a proton-sensing G protein-coupled receptor, was highly expressed in MtT/S cells, a growth hormone-producing and prolactin-producing pituitary tumor cell line. When we reduced the extracellular pH, growth hormone and prolactin mRNA expressions increased in the cells. Both increased expressions were partially suppressed by a GPR4 antagonist. We also found that extracellular acidification enhanced growth hormone-releasing factor-induced growth hormone secretion from MtT/S cells. These results suggest that GPR4 may play a role in hypersecretion of the hormone from hormone-producing pituitary tumors. A GPR4 antagonist will be a useful tool for preventing the hypersecretion.

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