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Differential regulation of insulin-like growth factor binding protein-1 and -2 by insulin in the baboon (Papio anubis) endometrium.

Fleming SD, Fazleabas AT, Bell SC - Reprod. Biol. Endocrinol. (2008)

Bottom Line: The purpose of this study was to examine the effect of insulin on expression and synthesis of IGFBP-1 and IGFBP-2 in the baboon endometrium in vitro.The inhibitory effects of insulin on IGFBP-1 were more evident in explants of non-pregnant tissue or tissue away from the implantation site.This effect was potentiated by steroids and hCG in the explant cultures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Obstetrics and Gynecology (MC808), College of Medicine, University of Illinois at Chicago, Illinois 60612-9998, USA. stevenf@westgate.wh.usyd.edu.au

ABSTRACT

Background: The purpose of this study was to examine the effect of insulin on expression and synthesis of IGFBP-1 and IGFBP-2 in the baboon endometrium in vitro.

Methods: Baboon endometrial explants collected from cycling, ovariectomized, steroid-treated, simulated-pregnant and pregnant animals were cultured for 48 h in the presence or absence of insulin, with or without estradiol, progesterone and hCG.

Results: Insulin clearly inhibited IGFBP-1 production and mRNA expression in a time- and dose-dependent manner, whereas IGFBP-2 synthesis was not significantly affected. The inhibitory effects of insulin on IGFBP-1 were more evident in explants of non-pregnant tissue or tissue away from the implantation site. In the absence of insulin, synthesis of IGFBP-1 was induced in explants with low levels of de novo synthesis whereas IGFBP-2 synthesis was inhibited. This effect was potentiated by steroids and hCG in the explant cultures.

Conclusion: Insulin differentially regulates endometrial IGFBP-1 and IGFBP-2 secretion in the baboon.

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Related in: MedlinePlus

Effect of insulin on IGFBP-1 and IGFBP-2 at the implantation and non-implantation sites. The effect of insulin (+/- Ins) on IGFBP-1 (BP-1) and IGFBP-2 (BP-2) secretion in culture media taken from endometrial explants of the implantation and non-implantation sites of a day 32 pregnant baboon (n = 1). Media samples were analysed by western blotting for IGFBP-1 (A) and IGFBP-2 (B), and by ELISA for IGFBP-1 (C) after 24 h (D-1) and 48 h (D-2) incubation. Values above each band in A and B represent their optical density. PF: Proteolytic fragment of IGFBP-1. Open bars: + Insulin; Closed bars: - Insulin.
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Figure 4: Effect of insulin on IGFBP-1 and IGFBP-2 at the implantation and non-implantation sites. The effect of insulin (+/- Ins) on IGFBP-1 (BP-1) and IGFBP-2 (BP-2) secretion in culture media taken from endometrial explants of the implantation and non-implantation sites of a day 32 pregnant baboon (n = 1). Media samples were analysed by western blotting for IGFBP-1 (A) and IGFBP-2 (B), and by ELISA for IGFBP-1 (C) after 24 h (D-1) and 48 h (D-2) incubation. Values above each band in A and B represent their optical density. PF: Proteolytic fragment of IGFBP-1. Open bars: + Insulin; Closed bars: - Insulin.

Mentions: Western blotting of conditioned medium harvested from explants of endometrium (either implantation site or non-implantation site tissue) collected from two baboons at day 32 of pregnancy, demonstrates the effect that the presence or absence of insulin in the culture medium has on the production of IGFBP-1 (Figure 4A) and IGFBP-2 (Figure 4B) is both modulated by pregnancy and is regionalized. In tissue from pregnant animals IGFBP-1 production is evident even in the presence of insulin, the inhibitory effect of insulin being less pronounced in tissue taken from the implantation site, where decidualization has begun (Figure 4A). Assay of these media samples for immunoreactive IGFBP-1 confirms the western blotting data (Figure 4C). Furthermore, a clear inverse dose-response relationship between the concentration of insulin in the culture medium and the production of IGFBP-1 from non-implantation site tissue can be seen (Figure 5), and this effect appears to be enhanced after two days of culture. Again, IGFBP-2 production is decreased in the absence of insulin, but only in tissue taken from the non-implantation site (Figure 4B).


Differential regulation of insulin-like growth factor binding protein-1 and -2 by insulin in the baboon (Papio anubis) endometrium.

Fleming SD, Fazleabas AT, Bell SC - Reprod. Biol. Endocrinol. (2008)

Effect of insulin on IGFBP-1 and IGFBP-2 at the implantation and non-implantation sites. The effect of insulin (+/- Ins) on IGFBP-1 (BP-1) and IGFBP-2 (BP-2) secretion in culture media taken from endometrial explants of the implantation and non-implantation sites of a day 32 pregnant baboon (n = 1). Media samples were analysed by western blotting for IGFBP-1 (A) and IGFBP-2 (B), and by ELISA for IGFBP-1 (C) after 24 h (D-1) and 48 h (D-2) incubation. Values above each band in A and B represent their optical density. PF: Proteolytic fragment of IGFBP-1. Open bars: + Insulin; Closed bars: - Insulin.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2254421&req=5

Figure 4: Effect of insulin on IGFBP-1 and IGFBP-2 at the implantation and non-implantation sites. The effect of insulin (+/- Ins) on IGFBP-1 (BP-1) and IGFBP-2 (BP-2) secretion in culture media taken from endometrial explants of the implantation and non-implantation sites of a day 32 pregnant baboon (n = 1). Media samples were analysed by western blotting for IGFBP-1 (A) and IGFBP-2 (B), and by ELISA for IGFBP-1 (C) after 24 h (D-1) and 48 h (D-2) incubation. Values above each band in A and B represent their optical density. PF: Proteolytic fragment of IGFBP-1. Open bars: + Insulin; Closed bars: - Insulin.
Mentions: Western blotting of conditioned medium harvested from explants of endometrium (either implantation site or non-implantation site tissue) collected from two baboons at day 32 of pregnancy, demonstrates the effect that the presence or absence of insulin in the culture medium has on the production of IGFBP-1 (Figure 4A) and IGFBP-2 (Figure 4B) is both modulated by pregnancy and is regionalized. In tissue from pregnant animals IGFBP-1 production is evident even in the presence of insulin, the inhibitory effect of insulin being less pronounced in tissue taken from the implantation site, where decidualization has begun (Figure 4A). Assay of these media samples for immunoreactive IGFBP-1 confirms the western blotting data (Figure 4C). Furthermore, a clear inverse dose-response relationship between the concentration of insulin in the culture medium and the production of IGFBP-1 from non-implantation site tissue can be seen (Figure 5), and this effect appears to be enhanced after two days of culture. Again, IGFBP-2 production is decreased in the absence of insulin, but only in tissue taken from the non-implantation site (Figure 4B).

Bottom Line: The purpose of this study was to examine the effect of insulin on expression and synthesis of IGFBP-1 and IGFBP-2 in the baboon endometrium in vitro.The inhibitory effects of insulin on IGFBP-1 were more evident in explants of non-pregnant tissue or tissue away from the implantation site.This effect was potentiated by steroids and hCG in the explant cultures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Obstetrics and Gynecology (MC808), College of Medicine, University of Illinois at Chicago, Illinois 60612-9998, USA. stevenf@westgate.wh.usyd.edu.au

ABSTRACT

Background: The purpose of this study was to examine the effect of insulin on expression and synthesis of IGFBP-1 and IGFBP-2 in the baboon endometrium in vitro.

Methods: Baboon endometrial explants collected from cycling, ovariectomized, steroid-treated, simulated-pregnant and pregnant animals were cultured for 48 h in the presence or absence of insulin, with or without estradiol, progesterone and hCG.

Results: Insulin clearly inhibited IGFBP-1 production and mRNA expression in a time- and dose-dependent manner, whereas IGFBP-2 synthesis was not significantly affected. The inhibitory effects of insulin on IGFBP-1 were more evident in explants of non-pregnant tissue or tissue away from the implantation site. In the absence of insulin, synthesis of IGFBP-1 was induced in explants with low levels of de novo synthesis whereas IGFBP-2 synthesis was inhibited. This effect was potentiated by steroids and hCG in the explant cultures.

Conclusion: Insulin differentially regulates endometrial IGFBP-1 and IGFBP-2 secretion in the baboon.

Show MeSH
Related in: MedlinePlus