Calcitonin is expressed in gonadtropes of the anterior pituitary gland: Its possible role in paracrine regulation of lactotrope function

Y. Ren, J. Chien, Y. P. Sun, G. V. Shah

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

Previous studies from this laboratory have shown that salmon (S) calcitonin (CT)-like immunoreactive peptide (CTI) is synthesized and secreted by the anterior pituitary (AP) gland. These studies also co-localized CTI to gonadotropes, and demonstrated that SCT is a potent inhibitor of lactotrope function. However, the molecular structure of putative gonadotrope-derived CTI that inhibits lactotrope function has not been defined. The present studies cloned CT cDNA (pit-CT cDNA) from a mouse gonadotrope LβT2 cell line using RT-PCR and rapid amplification of cDNA ends (RACE) techniques. Alignment of nucleotide sequences of pit-CT and mouse CT revealed greater than 99% homology between the sequences. The pit-CT cDNA was ligated into a mammalian expression vector, and the construct was transfected into LβT2 cells. Two stable transfectant cell lines (CT.U6/ A and B) were obtained by selection in G418. Subsequent S1-nuclease protection assay and immunocytochemistry results have shown that: (1) pit-CT peptide expressed by CT.U6 cell lines immunoreacted with GCT1-anti-SCT serum; (2) secretions of CT.U6 cells inhibited prolactin (PRL) release, PRL mRNA abundance and DNA synthesis of PRL-secreting GGH3 cells; and (3) CT.U6-induced inhibition was abolished by GCT1-anti-SCT serum. The studies also generated a riboprobe from the cloned pit-CT cDNA, and localized CT mRNA expression in gonadotropes of rat AP gland by in situ hybridization histochemistry. These results demonstrate that pit-CT mRNA is closely homologous to mouse CT mRNA; it is expressed by gonadotropes of the rat AP gland, and the peptide may significantly affect lactotrope function by inhibiting PRL release and cell proliferation.

Original languageEnglish (US)
Pages (from-to)217-228
Number of pages12
JournalJournal of Endocrinology
Volume171
Issue number2
DOIs
StatePublished - Jan 1 2001
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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