Calcitonin Decreases Thyrotropin-Releasing Hormone-Stimulated Prolactin Release through a Mechanism That Involves Inhibition of Inositol Phosphate Production*

Am, Judd; Kubota, Toshiro; Si, Kuan; Wd, Jarvis; Bl, Spangelo; Rm, MacLeod

doi:10.1210/endo-127-1-191

Cited by 31 publications

(15 citation statements)

References 42 publications

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“…Similarly, our studies suggest that CT inhibits PRL release and PRL gene transcription, and also attenuates thyrotropin-releasing hormone (TRH)-and suckling-induced PRL release and synthesis (Shah et al 1988, Judd et al 1990. CT is also a potent inhibitor of lactotrope proliferation (Shah et al 1999).…”

Section: Gct1-asct-absupporting

confidence: 57%

“…Previous evidence has shown that SCT, when administered either centrally or peripherally, inhibits PRL release in rats (Olgiati et al 1981(Olgiati et al , 1982(Olgiati et al , 1983. In vitro experiments from this and other laboratories have extended these earlier findings by demonstrating that SCT acts directly at the level of lactotropes to inhibit PRL release, PRL gene transcription and lactotrope cell proliferation (Shah et al 1988, 1999, Judd et al 1990, Sortino et al 1991, Zhang et al 1995. A role for the endogenous peptide in these processes is demonstrated by the findings that immunoneutralization of pit-CT with GCT1 anti-SCT serum causes a significant increase in PRL release from cultured AP cells as well as in ovariectomized conscious rats (Shah et al 1993.…”

Section: Gct1-asct-abmentioning

confidence: 53%

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

Ren¹,

Chien²,

Sun³

et al. 2001

Journal of Endocrinology

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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 L T2 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 L T2 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.

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Section: Gct1-asct-absupporting

confidence: 57%

Section: Gct1-asct-abmentioning

confidence: 53%

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

Ren¹,

Chien²,

Sun³

et al. 2001

Journal of Endocrinology

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“…It has also been implicated in the regulation of several functions in reproductive and neuroendocrine tissues (31)(32)(33)(34)(35).…”

Section: Discussionmentioning

confidence: 99%

Calcitonin Stimulates Multiple Stages of Angiogenesis by Directly Acting on Endothelial Cells

et al. 2005

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Although a strong correlation between neuroendocrine differentiation and angiogenesis of prostate cancer has been reported, no mechanistic link between the two events has been established. Because neuropeptide calcitonin is secreted by prostate tumors and endothelial cells are known to express calcitonin receptor-like receptor, we examined the potential action of calcitonin on endothelial cells. The presence of calcitonin receptor, calcitonin receptor-like receptor, and receptor activity-modifying proteins in human microvessel endothelial-1 cells was tested by reverse transcriptase-PCR (RT-PCR). The proangiogenic action of calcitonin was examined in several in vitro models of angiogenesis using HMEC-1 cells and also in vivo using dorsal skinfold assays. Calcitonin expression of PC-3M cells was modulated, and its effect on angiogenesis was examined in in vitro as well as in vivo models. The results of RT-PCR and radioligand receptor assays showed the presence of functional calcitonin receptor in HMEC-1 cells. Calcitonin stimulated all phases of angiogenesis through the calcitonin receptor, but its effect on tube morphogenesis by endothelial cells occurred at the concentration of the K d of calcitonin receptor. Silencing of calcitonin receptor expression in HMEC-1 cells abolished calcitonin-induced tube formation. Vascular endothelial growth factor antibodies attenuated but did not abolish calcitonin-induced tube morphogenesis. PC-3M prostate cancer cells induced angiogenesis in in vivo and in vitro models. Overexpression of calcitonin in PC-3M cells increased their angiogenic activity, whereas the silencing of calcitonin expression abolished it. These results show that prostate tumor-derived calcitonin may play an important role in prostate tumor growth by regulating intratumoral vascularization. (Cancer Res 2005; 65(18): 8519-29)

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“…In particular sCT has been shown to be a potent inhibitor of GH secretion in both humans [12]and rats [13]and is considered, at least under certain conditions, as a physiological PRL-inhibiting factor [14, 15]. …”

Section: Introductionmentioning

confidence: 99%

Effects of Amylin and Salmon Calcitonin on β-Endorphin-Induced Growth Hormone and Prolactin Secretion in the Rat

et al. 1998

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In this study we examined the possible interplay of amylin (AMY) and salmon calcitonin (sCT) in the central control of growth hormone (GH) and prolactin (PRL) secretion in male rats. For this purpose we first compared effects of central intracerebroventricular (i.c.v.) admininstration of various doses of AMY (2.5–2,500 ng/rat) and sCT (2.2–220 ng/rat) on β-endorphin (β-END, 0.5 µg/rat)-induced GH and PRL secretion. AMY and sCT dose-dependently inhibited β-END-induced GH secretion, whereas only sCT was able to inhibit β-END-induced PRL secretion. To examine whether the GH inhibitory effect of AMY was due to the possible cross-reactivity of AMY and sCT on the same receptors in the CNS, we pretreated some rats with the AMY antagonist (AMY_8–37, 2.5 µg/rat, i.c.v.). AMY_8–37 significantly enhanced the GH-stimulatory action of β-END. AMY_8–37, administered prior to AMY and sCT, significantly removed the inhibitory effect of both AMY and sCT on β-END-induced GH release, suggesting that both peptides mediate their response on GH through a common receptor. In vitro competition binding studies on rat hypothalamic membranes have shown that both AMY and sCT compete with [¹²⁵I]rAMY binding with half inhibition (IC₅₀) values of 3.6 × 10^–11 and 1.6 × 10^–10 M, respectively. Binding of [¹²⁵I]sCT was inhibited by sCT with an IC₅₀ of 1.09 × 10^–10M and to a lesser extent by AMY with an IC₅₀ of 1.3 × 10^–6 M. Thus it is possible that the two peptides recognize a common hypothalamic receptor but with different affinities (sCT > AMY). Overall these data indicate that AMY behaves as a mimic of sCT in the central control of GH secretion. The failure of AMY, at variance with sCT, to modify the PRL-releasing activity of β-END indicates that different receptor subtypes for sCT are involved in the endocrine effects of sCT and only those mediating the modulatory action of GH respond to AMY.

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Calcitonin Decreases Thyrotropin-Releasing Hormone-Stimulated Prolactin Release through a Mechanism That Involves Inhibition of Inositol Phosphate Production*

Cited by 31 publications

References 42 publications

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

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

Calcitonin Stimulates Multiple Stages of Angiogenesis by Directly Acting on Endothelial Cells

Effects of Amylin and Salmon Calcitonin on β-Endorphin-Induced Growth Hormone and Prolactin Secretion in the Rat

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