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Exp Clin Endocrinol Diabetes 1990; 96(4): 8-14
DOI: 10.1055/s-0029-1210982
Original

© J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York

Changes in Content of Prolactin mRNA during the Rat Estrous Cycle

N. Shimokawa1 , Y. Kato1 , 2 , K. Imai3 , K. Wakabayashi1
  • 1Hormone Assay Center, (Director: Prof. Dr. K. Wakabayashi)
  • 2Departments of Protein Chemistry (Director: Prof. Dr. K. Iwai)
  • 3Pharmaceutical Chemistry (Director: Prof. Dr. H. Takikawa), Institute of Endocrinology (Director: Prof. Dr. K. Kurosumi), Gunma University, Maebashi/Japan.
Further Information

Publication History

1989

Publication Date:
16 July 2009 (online)

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Summary

An attempt was made to clarify the relationship between the synthesis of prolactin (PRL) and its secretion during the rat estrous cycle by examining the changes in PRL messenger RNA (mRNA), PRL secretion and anterior pituitary PRL content. At various stages of the estrous cycle, pituitary and serum levels of PRL and growth hormone (GH) were measured by radioimmunoassay, while their respective mRNA contents were determined by the hybridization method. The content of pituitary PRL mRNA did not increase in parallel with the increment of the serum level of the hormone. Significant increases in PRL mRNA were observed as three peaks; 1st peak at 14:00 on the proestrus (PE) day, 2nd peak at 4:00 and 3rd peak at 22:00 on the estrus (E) day. The GH levels in the pituitary and serum, or the change in PRL mRNA appeared to be unrelated to the rat estrous cycle. From the present results, we speculate that the three peaks of PRL mRNA content might be ascribable to the direct effect of estrogen on transcription, indirect activation of transcription followed by rapid and massive secretion of PRL, and mammotrope proliferation, respectively.

Key words

PRL mRNA - GH mRNA - Estrous cycle - Rat pituitary

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