scholarly journals Interactions of insulin-like growth factor-I, insulin and estradiol with GnRH-stimulated luteinizing hormone release from female rat gonadotrophs

2001 ◽  
pp. 73-79 ◽  
Author(s):  
YX Xia ◽  
JM Weiss ◽  
S Polack ◽  
K Diedrich ◽  
O Ortmann
Keyword(s):  
Pituitary Cells ◽  
Female Rat ◽  
Serum Free Medium ◽  
Free Medium ◽  
Estradiol Treatment ◽  
Gonadotropin Secretion ◽  
Serum Free ◽  
Igf I ◽  
Lh Release ◽  
Lh Secretion

BACKGROUND: It is well established that ovarian steroids modulate gonadotropin secretion from anterior pituitary cells. It has been speculated that insulin and IGF-I might influence gonadotropin secretion. OBJECTIVE: To investigate the effects of IGF-I and estradiol alone, or combinations of IGF-I with insulin and estradiol on GnRH-stimulated LH release from female rat pituitary cells in serum-supplemented and serum-free culture conditions. METHODS: Pituitary cells were incubated for 24 h or 48 h with a series of increasing concentrations of IGF-I or estradiol and stimulated with 1 nmol/l GnRH for 3 h. To determine the interaction of IGF-I and estradiol on GnRH-stimulated LH secretion, cells were exposed to increasing concentrations of IGF-I and 100 pmol/l estradiol for 24 h. We also investigated the effects of combined treatment with IGF-I and insulin on GnRH-stimulated LH secretion. RESULTS: Our findings indicate that long-term IGF-I treatment (24 h) alone has a significant augmenting effect on GnRH-stimulated LH release in serum-free medium only, with a maximum at low concentrations (10 and 100 pmol/l). Estradiol significantly increased GnRH-induced LH release in a dose-dependent manner. The extent of GnRH-stimulated LH secretion by long-term estradiol treatment (24 h) was significantly greater in serum-supplemented (+42%) medium than in serum-free medium. Estradiol facilitated IGF-I-primed LH responses to GnRH in serum-free medium. In contrast, in serum-supplemented medium, the facilitating potential of estradiol was lower. We also found that, in GnRH-stimulated cells, LH release was augmented by insulin treatment, in contrast to quiescent cells that had been pretreated with 100 pmol/l IGF-I alone and 1 nmol/l insulin alone. CONCLUSIONS: IGF-I and to a lesser extent insulin stimulate GnRH-induced LH secretion from pituitary gonadotrophs. This action is enhanced by estradiol treatment of the cells. However, the well known stimulatory action of estradiol on LH secretion is dependent on the presence of growth factors.

scholarly journals Isolated porcine ovarian follicles as a model for the study of hormone and growth factor action on ovarian secretory activity

1998 ◽  
Vol 159 (2) ◽  
pp. 313-321 ◽  
Author(s):  
AV Sirotkin ◽  
AV Makarevich ◽  
J Kotwica ◽  
PG Marnet ◽  
HB Kwon ◽  
...  
Keyword(s):  
Growth Factor ◽  
Ovarian Follicles ◽  
Serum Free Medium ◽  
Free Medium ◽  
Ovarian Steroid ◽  
Serum Free ◽  
Factor Binding ◽  
Estradiol Secretion ◽  
Igf I ◽  
Igfbp 3

The aim of our in vitro experiments with isolated porcine ovarian follicles was to study the effects of gonadotropins, GH, IGF-I and oxytocin (OT) on release of ovarian steroid, OT, IGF-I, insulin-like growth factor-binding protein-3 (IGFBP-3), prostaglandin F (PGF), prostaglandin E (PGE) and cAMP. It was found that quarters of ovarian follicles cultured for 8 days produced significant amounts of progesterone, estradiol-17 beta, OT and IGFBP-3 with peaks of accumulation from the 3rd to the 8th day of culture. Addition of serum promoted progesterone, estradiol and OT release, whilst accumulation of IGFBP-3 was maintained to a greater extent in serum-free medium. GH (10 ng/ml or above) was able to inhibit androstenedione, OT, PGF and IGFBP-3, to stimulate IGF-I and cAMP, and to alter testosterone and PGE release by follicles cultured in serum-supplemented and/or serum-free medium. IGF-I (10 ng/ml or more) inhibited androstenedione and PGF secretion, stimulated testosterone, estradiol, OT and cAMP production, but did not influence progesterone, IGFBP-3 or PGE output in these conditions. OT (100 ng/ml) was able to inhibit androstenedione and to stimulate testosterone, IGF-I, PGF and PGE, but not estradiol or IGFBP-3 release. A stimulatory effect of LH on progesterone and OT and an inhibitory influence of LH on estradiol secretion in the serum-supplemented medium were observed. FSH in these conditions stimulated OT, but not progesterone or estradiol secretion. The use of this experimental model suggests the involvement of gonadotropins, OT, GH and IGF-I in the control of ovarian steroid and nonapeptide hormone, growth factor, growth factor-binding protein, prostaglandin and cyclic nucleotide production. The stimulatory effect of GH on IGF-I, and the stimulatory influence of IGF-I on OT, as well as coincidence of the majority of effects of IGF-I and OT, suggest the existence of a GH-IGF-I-OT axis. On the other hand, the different patterns of action of GH and IGF-I on OT, estrogen and IGFBP-3 suggest that part of the GH effect on ovarian cells is IGF-I independent.

scholarly journals IGF-I-induced enhancement of contractile response in organ-cultured aortae from diabetic rats is mediated by sustained thromboxane A2 release from endothelial cells

2005 ◽  
Vol 186 (2) ◽  
pp. 367-376 ◽  
Author(s):  
Tsuneo Kobayashi ◽  
Takayuki Matsumoto ◽  
Katsuo Kamata
Keyword(s):  
Endothelial Cells ◽  
Organ Culture ◽  
Contractile Response ◽  
Diabetic Rats ◽  
Receptor Expression ◽  
Diabetic Rat ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Igf I

We have investigated the mechanisms underlying the changes in vascular contractile responsiveness induced by insulin and IGF-I in established streptozotocin-induced diabetic rats. The contractile response to noradrenaline (NA) in organ-cultured diabetic rat aortae cultured with insulin or IGF-I was significantly greater than the corresponding responses in (a) diabetic rat aortae cultured in serum-free medium and (b) control rat aortae cultured with insulin or IGF-I. In aortae from which the endothelium was removed after organ culture the contractile response to NA was greater in those cultured with insulin or IGF-I than in those cultured in serum-free medium. This was not true of aortae endothelium denuded before organ culture. The IGF-I-induced enhancement was prevented by treatment with indomethacin (cyclo-oxygenase inhibitor), SQ29548 (thromboxane (TX) A2 receptor antagonist) or fregrelate (TXA2 synthase inhibitor). IGF-I-induced production of TXB2, a metabolite of TXA2, was greater in diabetic than in control aortae and was attenuated by endothelium denudation, indomethacin or AG1024 (IGF-I receptor inhibitor). The expression of the protein and mRNA for the IGF-I receptor (as assessed by RT-PCR and immunohistochemistry) was markedly increased within endothelial cells in diabetic aortae but only slightly increased within smooth muscle cells (versus control rat aortae). Thus, the NA-induced contractile response in aortae from diabetic rats was enhanced by both insulin and IGF-I and this enhancement may be mediated by sustained cyclo-oxygenase-dependent TXA2 production from endothelial cells. The observed enhancement of IGF-I receptor expression within endothelial cells may be causally related to the potentiation of vascular contractility and the increase in TXA2 production.

Insulin-like growth factor-I and its autocrine role in growth of MCF-7 human breast cancer cells in culture

1989 ◽  
Vol 3 (3) ◽  
pp. 183-190 ◽  
Author(s):  
K. A. Freed ◽  
A. C. Herington
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Growth Factor ◽  
Breast Cancer Cells ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Factor I ◽  
Igf I ◽  
Mcf 7

ABSTRACT Human MCF-7 breast cancer cells have been studied to determine their suitability as an autocrine model for the synthesis, secretion and action of insulin-like growth factor-I (IGF-I). Secretion of immunoreactive (ir-) IGF-I into serum-free medium was very low (<500 pg/106 cells per day). Northern blot hybridization detected at least two IGF-I messenger RNA transcripts (∼4·6 and ∼1·8 kb) which were similar in size to those reported in other human and rat tissues. IGF-II mRNA was also detected but at low abundance. Cell proliferation was stimulated in a dose-responsive manner by exogenous IGF-I (10–30 ng/ml). Addition of a monoclonal antibody against IGF-I to MCF-7 cells in serum-free medium caused an inhibition of cell proliferation, suggesting that endogenous locally produced IGF-I does play an autocrine/paracrine role in MCF-7 cell growth. Proliferation of MCF-7 cells was sensitive to oestradiol (10 nm) in the absence but not in the presence of the weakly oestrogenic pH indicator phenol red. Neither IGF-I secretion nor IGF-I mRNA synthesis, however, was affected by addition of oestradiol. Similarly, GH, dexamethasone or dexamethasone plus oestradiol had no effect on either parameter. These data indicate that MCF-7 cells synthesize, secrete and respond to IGF-I. The very low levels of ir-IGF-I produced and their apparent lack of hormonal modulation suggest, however, that further studies are required to establish whether IGF-I plays a major physiological role in growth and development of MCF-7 cells.

Evidence for a single glucocorticoid regulated pool of adrenocorticotropin in sheep anterior pituitary

1995 ◽  
Vol 268 (1) ◽  
pp. E85-E91
Author(s):  
R. J. Kemppainen ◽  
T. P. Clark
Keyword(s):  
Anterior Pituitary ◽  
Adrenocorticotropic Hormone ◽  
Culture Medium ◽  
Pituitary Cells ◽  
Serum Free Medium ◽  
Free Medium ◽  
Isolated Cells ◽  
Serum Free ◽  
Fractional Release ◽  
Acth Release

The goal of this study was to determine whether separate glucocorticoid-sensitive releasable pools of adrenocorticotropic hormone (ACTH) could be distinguished in sheep anterior pituitary cells. Isolated cells were cultured in serum-free medium containing 0–10 nM cortisol (F) for 7–11 days to determine whether variation in the glucocorticoid environment selectively affected ACTH release stimulated by corticotropin-releasing hormone (CRH) or arginine vasopressin (AVP). Secretion was studied using a microperifusion system. The results indicated that while the concentration of F in the medium bathing the cells profoundly influenced the magnitude of ACTH released in response to either peptide, the fractional release of total ACTH was unchanged. F concentration in culture medium similarly did not alter the negative-feedback effectiveness of a larger dose of F applied to cells 45 min before treatment with CRH or AVP. These results support the existence of a single glucocorticoid-sensitive pool of ACTH in corticotrophs.

Effects of insulin-like growth factor-I (IGF-I) and IGF-II on the growth of antler cells in vitro

1994 ◽  
Vol 143 (3) ◽  
pp. 461-469 ◽  
Author(s):  
M Sadighi ◽  
S R Haines ◽  
A Skottner ◽  
A J Harris ◽  
J M Suttie
Keyword(s):  
Growth Factor ◽  
Thymidine Uptake ◽  
Dependent Manner ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Antler Growth ◽  
Igf I ◽  
And Cartilage

Abstract The effects of insulin-like growth factors -I and -II (IGF-I and -II) on the growth of undifferentiated (fibroblast zone) cells from the growing tip of red deer velvet antlers and from cells 1·5 cm distal to the growing tip (cartilage zone) were investigated in primary cell culture. The addition of IGF-I or IGF-II to the medium of cultures preincubated in serum-free medium for 24 h increased the rate of [3H]thymidine uptake in a dose-dependent manner in both cell types, with maximal stimulation occurring when 1 nm–30 nm was added. The addition of IGF-II to the incubation medium containing IGF-I did not cause a further increase in [3H]thymidine uptake in either cell type over and above each growth factor alone, indicating that there were unlikely to be synergistic effects of IGF-II on the mitogenicity of IGF-I. Binding studies were carried out using 3 × 105 fibroblast zone cells and cartilage zone cells after they had been incubated in serum-free medium for 24 h. 125I-Labelled IGF-I (10−9 m) in a final volume of 200 μl was added to each culture and incubation carried out at 4 °C for a further hour. 125I-Labelled IGF-I bound specifically to both fibroblasts and cartilage zone cells; binding was displaced by both unlabelled IGF-I and by IGF-I antibody. These findings indicate that IGF-I and IGF-II are important mediators for antler growth in vitro and suggest that in view of correlations between IGF-I and antler growth, IGF is functionally significant in controlling velvet antler growth in vivo. Journal of Endocrinology (1994) 143, 461–469

Partial loss of responsiveness of human fetal pituitary cells to hGHRH after chronic exposure

1989 ◽  
Vol 121 (5) ◽  
pp. 721-726 ◽  
Author(s):  
Zeev Blumenfeld ◽  
Paivi Tapaneinen ◽  
Selna L. Kaplan ◽  
Melvin M. Grumbach ◽  
Robert B. Jaffe
Keyword(s):  
Chronic Exposure ◽  
Pituitary Cells ◽  
Human Fetuses ◽  
Serum Free Medium ◽  
Free Medium ◽  
Partial Loss ◽  
Initial Exposure ◽  
Serum Free ◽  
Gh Secretion ◽  
Subsequent Exposure

Abstract. Synthetic hGHRH was incubated with dispersed pituitary cells from 14 human fetuses at 14–23 weeks of fetal age. After at least three days following plating the cells on an extracellular matrix in serum-containing medium, 3 h incubation with hGHRH in serum-free medium induced a significant increase in GH secretion into the medium at concentrations of hGHRH of 0.01 nmol/1 or higher. After 24 h exposure to 0.5 nmol/1 hGHRH, subsequent incubation with 0.5 nmol/1 hGHRH for 3 h induced significantly lower GH secretion into the medium compared to the GH secretion by cells exposed previously to medium alone. In contrast, when the subsequent exposure to hGHRH was at 10-fold higher concentrations than the concentration present in the initial exposure, GH secretion into the medium did not significantly decrease compared to previously untreated cells. These results suggest that desensitization (down-regulation) of GHRH receptors on somatotropes may be involved in the mechanism by which prior GHRH exposure inhibits GH secretion in response to subsequent GHRH administration. Such desensitization seems to occur in the human fetus but is incomplete. The desensitization may be overcome by increasing the GHRH concentrations with subsequent exposure, suggesting that cellular GH depletion is not responsible for the decreased responsiveness observed.

Growth factor-extracellular matrix synergy in the control of trophoblast invasion

2000 ◽  
Vol 28 (2) ◽  
pp. 199-202 ◽  
Author(s):  
J. D. Aplin ◽  
H. Lacey ◽  
T. Haigh ◽  
C. J. P. Jones ◽  
C.-P. Chen ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Growth Factor ◽  
Transforming Growth Factor ◽  
First Trimester ◽  
Trophoblast Invasion ◽  
Cell Phenotype ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Igf I

At the periphery of the human placenta, trophoblast attaches to the uterine wall. The tissue interface contains many anchoring sites, with cytotrophoblast columns that form bridges between the overlying extraembryonic (villous) mesenchyme and the maternal decidual stroma beneath. From the periphery of these columns, large numbers of trophoblast cells detach, migrate through the decidua and eventually colonize and transform maternal arteries. In this way the placenta increases and gives priority to the maternal blood supply to the conceptus. We have shown that when early villous tissue is explanted on a collagen gel in serum-free medium, anchoring-site morphogenesis occurs. Thus, in the presence of placental mesenchyme but in the absence of maternal cells, contact with a permissive extracellular matrix (ECM) is necessary and sufficient for cytotrophoblast column development. Proliferation of trophoblast occurs, followed by differentiation into a columnar cell phenotype in which cells remain attached to one another and to the ECM. At this stage, interaction between fibronectin and integrin α5β1 at the cell surface stabilizes the column and the cells remain as a contiguous multilayered sheet. However, the addition of serum-free conditioned medium from first-trimester placental fibroblasts stimulates cytotrophoblast to detach from the distal column and migrate in streams across the ECM. The removal of insulin-like growth factor I (IGF-I) from the fibroblast medium decreases streaming activity, whereas the addition of exogenous IGF-I (10 ng/ml) to serum-free medium produces a streaming phenotype. In contrast, transforming growth factor β1 (10 ng/ml) maintains the cells in a tight sheet. These results suggest the possibility of a paracrine interaction between villous mesenchyme and cytotrophoblast in anchoring sites to stimulate the infiltration of the maternal ECM by trophoblast. Such a mechanism would be self-limiting because the signal diminishes with distance from the placenta.

Exogeneous factors are not necessary in attachment, spreading and polarization of hela cells

1978 ◽  
Vol 36 (2) ◽  
pp. 310-311
Author(s):  
W. Liebrich
Keyword(s):  
Hela Cells ◽  
Calf Serum ◽  
Glass Tube ◽  
Serum Free Medium ◽  
Nacl Solution ◽  
Free Medium ◽  
Minimum Essential Medium ◽  
Serum Free ◽  
All Solutions ◽  
Glass Support

HeLa cells were grown for 2-3 days in EAGLE'S minimum essential medium with 10% calf serum (S-MEM; Seromed, München) and then incubated for 24 hours in serum free medium (MEM). After detaching the cells with a solution of 0. 14 % EDTA and 0. 07 % trypsin (Difco, 1 : 250) they were suspended in various solutions (S-MEM = control, MEM, buffered salt solutions with or without Me++ions, 0. 9 % NaCl solution) and allowed to settle on glass tube slips (Leighton-tubes). After 5, 10, 15, 20, 25, 30, 1 45, 60 minutes 2, 3, 4, 5 hours cells were prepared for scanning electron microscopy as described by Paweletz and Schroeter. The preparations were examined in a Jeol SEM (JSM-U3) at 25 KV without tilting.The suspended spherical HeLa cells are able to adhere to the glass support in all solutions. The rate of attachment, however, is faster in solutions without serum than in the control. The latter is in agreement with the findings of other authors.

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