Relationships between concentrations of steroids, igf-1 and igf binding proteins during follicular development in the ewe

Proceedings of the British Society of Animal Science ◽

10.1017/s0308229600028245 ◽

1995 ◽

Vol 1995 ◽

pp. 56-56

Author(s):

M. Khalid ◽

W. Haresign

Keyword(s):

Follicular Fluid ◽

Biochemical Markers ◽

Binding Proteins ◽

Ovarian Function ◽

Follicular Development ◽

Physiological Status ◽

Igf Binding Proteins ◽

Ovarian Cells ◽

Igf Binding

Insulin-like growth factor-1 (IGF-1) is one of the potential autocrine/paracrine regulators of ovarian function. Not only do relationships exist between follicular fluid concentrations of IGF-1 and various biochemical markers of follicular differentiation, but IGF-1 has also been shown to stimulate both proliferation and steroidogenesis in ovarian cells in vitro (Adashi et al., 1985). The actions of IGF-1 are thought to be modulated by IGF-binding proteins (IGFBPs). Indeed, follicular growth and atresia in the ewe have been reported to be determined more by changes in IGFBPs than by changes in IGF-1 (Monget et al., 1993). However, in mat particular study, stage of follicular development was determined by follicle size and by microscopic examination of the granulosa cells of individual follicles rather than by biochemical markers of follicle status. The objective of the present study was, therefore, to investigate changes in IGF-1 and IGFBPs levels in follicular fluid and to relate these to the physiological status as determined by steroidogenic content of follicular fluid.

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Effects of IGF-I bioavailability on bovine preantral follicular development in vitro

Reproduction ◽

10.1530/rep-06-0382 ◽

2007 ◽

Vol 133 (6) ◽

pp. 1121-1128 ◽

Cited By ~ 55

Author(s):

Fiona H Thomas ◽

Bruce K Campbell ◽

David G Armstrong ◽

Evelyn E Telfer

Keyword(s):

Follicular Development ◽

Follicle Development ◽

Dependent Manner ◽

Igf Binding Proteins ◽

Preantral Follicles ◽

Follicle Diameter ◽

Igf I ◽

Igf Binding ◽

Development In Vitro

The aim of this study was to determine the effect of regulation of IGF-I bioavailability on preantral follicle development in vitro. Bovine preantral follicles were cultured for 6 days in serum-free medium with increasing doses of Long R3 (LR3) IGF-I (an analog with low affinity for IGF-binding proteins (IGFBPs)), or human recombinant IGF-I (hrIGF-I). Follicle diameter and estradiol production were measured every second day. On day 6, ratios of oocyte/follicle diameter and oocyte morphology were assessed by histological examination, and IGFBP-2 and -3 were detected by immunocytochemistry and in situ hybridization respectively. Both types of IGF-I increased follicle diameter in a dose-dependent manner (P < 0.05) and increased estradiol production over control levels (P < 0.05). However, follicles treated with LR3 IGF-I and the highest concentration of hrIGF-I (1000 ng/ml) had smaller oocyte/follicle ratios, and increased oocyte degeneration, compared with controls or follicles treated with physiological concentrations of hrIGF-I (P < 0.05). IGFBPs were detected in cultured preantral follicles, indicating a requirement for regulation of IGF bioavailability during the early stages of follicular development. Specifically, IGFBP-3 mRNA was found to be expressed in oocytes, and IGFBP-2 immunoreactivity was detected in oocytes and granulosa cells of cultured follicles. In summary, the regulation of IGF-I bioavailability by IGFBPs is necessary for the co-ordination of oocyte and follicle development in vitro.

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GH/IGF e neoplasia: o que há de novo nesta associação

Arquivos Brasileiros de Endocrinologia & Metabologia ◽

10.1590/s0004-27302005000500026 ◽

2005 ◽

Vol 49 (5) ◽

pp. 833-842 ◽

Cited By ~ 3

Author(s):

Angela M. Spinola e Castro ◽

Gil Guerra-Júnior

Keyword(s):

Growth Factors ◽

Binding Proteins ◽

De Novo ◽

Igf Binding Proteins ◽

Igf I ◽

Ciclo Celular ◽

Igf Binding ◽

Insulin Like Growth Factors

Estudos in vitro e em animais sugerem que os membros do sistema insulin-like growth factors (IGFs), incluindo IGF-I, IGF-II, receptores de IGF-I e IGF-II (IGF-IR e IGF-IIR), e as IGF-binding proteins (IGFBPs) podem ter um importante envolvimento no desenvolvimento e na progressão de neoplasias. Mais especificamente, as IGFs promovem a progressão do ciclo celular e inibem a apoptose tanto por ação direta com outros fatores de crescimento como por ação indireta interagindo com outros sistemas moleculares intracelulares envolvidos na promoção e/ou progressão do câncer. Além disso, inúmeros estudos epidemiológicos têm sugerido que concentrações elevadas das IGFs, independente das alterações nas IGFBPs, podem estar associadas a um aumento no risco de desenvolver determinadas neoplasias. Esta revisão tem como objetivo apresentar o envolvimento do sistema IGF na regulação tumoral, os principais estudos epidemiológicos realizados e o risco de desenvolvimento de neoplasia em pacientes (com ou sem história pessoal de neoplasia prévia) que receberam hormônio de crescimento (rhGH). É importante salientar que o uso clínico de rhGH, nas indicações aprovadas internacionalmente, é seguro e não existem evidências, até o momento, da associação com o desenvolvimento de neoplasias.

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Secretion of insulin-like growth factor-I (IGF-I) and IGF-binding proteins from bovine mammary tissue in vitro

Journal of Endocrinology ◽

10.1677/joe.0.1280219 ◽

1991 ◽

Vol 128 (2) ◽

pp. 219-228 ◽

Cited By ~ 32

Author(s):

P. G. Campbell ◽

T. C. Skaar ◽

J. R. Vega ◽

C. R. Baumrucker

Keyword(s):

Growth Factor ◽

Binding Proteins ◽

Conditioned Media ◽

Mammary Tissue ◽

Igf Binding Proteins ◽

Factor I ◽

Igf I ◽

Igf Binding ◽

Bovine Mammary Tissue

ABSTRACT In vitro, insulin-like growth factor-I (IGF-I) promotes both growth and development of bovine mammary tissue. In vivo, the effects of IGF-I may encompass endocrine, paracrine or autocrine mediation. We addressed the possibility of paracrine/autocrine effects of IGF-I in the mammary gland by examining the in-vitro secretion of IGF-I and IGF-binding proteins (IGFBPs) from bovine mammary tissue. Bovine mammary explants from pregnant non-lactating and lactating non-pregnant animals were found to synthesize and secrete IGF-I and IGFBPs. Mammary acini cultures, representative of mammary secretory epithelia, secreted both IGF-I and IGFBP, but synthesized only IGFBP. Concentrations of IGF-I in conditioned media from explants were 1·54 and 0·72 fmol/μg DNA for pregnant and lactating animals respectively. Concentrations of IGFBPs in conditioned media from explants were similar for both physiological states at 2529 pmol 125I-labelled IGF-I bound/pg DNA. Ligand/Western blotting procedures identified four IGFBPs of 29, 33, 37 and 44 kDa for acini cultures and five IGFBPs of 28, 31, 36, 44 and 46 kDa for explant cultures. Similar affinities for IGF-I and IGF-II were shown by IGFBP, using 125I-labelled recombinant human IGF-I as the competing ligand (median effective dose (ED50) of 0·085 pmol). When 125I-labelled bovine IGF-II was used as the ligand, only bovine IGF-II (ED50 of 0·25 pmol) inhibited binding. The addition of prolactin, insulin and cortisol, with or without GH, did not affect secretion of either IGF-I or IGFBP. This report describes the ability of normal mammary tissue to synthesize and secrete IGF-I and IGFBPs. Journal of Endocrinology (1991) 128, 219–228

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Selection of the Dominant Follicle and Insulin-Like Growth Factor (IGF)-Binding Proteins: Evidence that Pregnancy-Associated Plasma Protein A Contributes to Proteolysis of IGF-Binding Protein 5 in Bovine Follicular Fluid

Endocrinology ◽

10.1210/en.2002-220657 ◽

2003 ◽

Vol 144 (2) ◽

pp. 437-446 ◽

Cited By ~ 49

Author(s):

G. M. Rivera ◽

J. E. Fortune

Keyword(s):

Proteolytic Activity ◽

Plasma Protein ◽

Follicular Fluid ◽

Binding Proteins ◽

Protein A ◽

Positive Control ◽

Dominant Follicle ◽

Igf Binding Proteins ◽

Igf Binding ◽

Igf Binding Protein

Development of a dominant follicle is associated with decreased intrafollicular low molecular weight IGF-binding proteins (namely IGFBP-2, -4, and -5) and increased proteolysis of IGFBP-4 by pregnancy-associated plasma protein A (PAPP-A). In addition to IGFBP-4 proteolytic activity, bovine follicular fluid contains strong proteolytic activity for IGFBP-5, but not for IGFBP-2. Here we show that the IGFBP-5 protease present in bovine follicular fluid is a neutral/basic pH-favoring, Zn2+ metalloprotease very similar to the previously described IGFBP-4 protease. We hypothesized that immunoneutralization and immunoprecipitation with anti-PAPP-A antibodies would result in abrogation of the IGFBP-4, but not the IGFBP-5, proteolytic activity in follicular fluid. As expected, anti-PAPP-A antibodies were able to neutralize and precipitate the IGFBP-4, but not the IGFBP-5, proteolytic activity of human pregnancy serum, which was used as a positive control for PAPP-A. Surprisingly, immunoneutralization and immunoprecipitation of follicular fluid from bovine preovulatory follicles with anti-PAPP-A antibodies abrogated both IGFBP-4 and IGFBP-5 proteolysis. Quantitative results derived from phosphorimaging revealed a complete inhibition of both IGFBP-4 and -5 proteolysis by follicular fluid incubated for 2 or 5 h in the presence of anti-PAPP-A antibodies. After 18 h of incubation, anti-PAPP-A antibodies still inhibited IGFBP-5 degradation, although with an efficiency lower than that for IGFBP-4 degradation. Both proteolytic activities have identical electrophoretic mobility, and a single band (∼400 kDa) was detected by Western immunoblotting of bovine follicular fluid with anti-PAPP-A antibodies. Proteolysis of IGFBP-5 was readily detectable in follicular fluid from dominant follicles and was negligible in subordinate follicles from the same cohort. These results suggest that an active intrafollicular IGFBP-4/-5 proteolytic system, in which PAPP-A is the major protease involved, is an important determinant of follicular fate.

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Co-expression of messenger ribonucleic acids encoding IGF-I, IGF-II, type I and II IGF receptors and IGF-binding proteins (IGFBP-1 to -6) during follicular development in the ovary of seasonally anoestrous ewes

Animal Reproduction Science ◽

10.1016/j.anireprosci.2003.10.012 ◽

2004 ◽

Vol 84 (1-2) ◽

pp. 93-105 ◽

Cited By ~ 15

Author(s):

P.M Hastie ◽

O.M Onagbesan ◽

W Haresign

Keyword(s):

Binding Proteins ◽

Follicular Development ◽

Type I ◽

Igf Binding Proteins ◽

Ribonucleic Acids ◽

Igf Receptors ◽

Igf I ◽

Igf Binding

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The content of IGF1 and igf binding proteins in porcine follicular fluid at different stages of the estrous cycle

Theriogenology ◽

10.1016/0093-691x(95)92459-m ◽

1995 ◽

Vol 43 (1) ◽

pp. 305

Author(s):

K. Raun ◽

B.Sehested Hansen ◽

J. Søndergård-Andersen ◽

M. Schmidt

Keyword(s):

Estrous Cycle ◽

Follicular Fluid ◽

Binding Proteins ◽

Igf Binding Proteins ◽

Igf Binding

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Differences in the association of insulin-like growth factor-I (IGF-I) and IGF-I variants with rat, sheep, pig, human and chicken plasma-binding proteins

Journal of Endocrinology ◽

10.1677/joe.0.1400475 ◽

1994 ◽

Vol 140 (3) ◽

pp. 475-482 ◽

Cited By ~ 14

Author(s):

A P D Lord ◽

S E P Bastian ◽

L C Read ◽

P E Walton ◽

F J Ballard

Keyword(s):

Binding Proteins ◽

Rat Plasma ◽

Size Exclusion ◽

Free Form ◽

Igf Binding Proteins ◽

Igf I ◽

Exclusion Chromatography ◽

Igf Binding

Abstract Associations between labelled insulin-like growth factors (IGFs) and IGF-binding proteins in plasma have been compared in the rat, sheep, human, pig and chicken. The IGFs tested were recombinant human IGF-I, the truncated variant, des(1–3)IGF-I, and LR3IGF-I, an extended form that had been engineered so as to minimize interactions with IGF-binding proteins. Marked species differences were demonstrated, notably that the IGF-I variants which exhibited extremely weak binding in rat plasma bound significantly in plasma from the other species. This result was shown both by size-exclusion chromatography of labelled IGFs added to plasma, in which the extent of variant IGF-I binding decreased in the order sheep>human>pig=chicken>rat, and by competition for labelled IGF-I binding in vitro, in which the order was pig=chicken>sheep>human>rat. Notwithstanding these differences, the two IGF-I variants showed only slight between-species binding differences when tested with purified rat, sheep and human IGF-binding protein-3. Ligand blotting experiments with plasma from the five species similarly showed a consistent pattern in that IGF-I binding was much greater than des(1–3)IGF-I binding, which in turn was greater than LR3 IGF-I binding. These experiments suggest first that IGF-binding properties measured after the removal of endogenous IGFs do not always reflect the situation with untreated plasma or in vivo, and secondly, the increased potencies of des(1–3)IGF-I and LR3 IGF-I in rat growth studies that have been ascribed to higher concentrations of these peptides in the free form cannot necessarily be extended to other species. Journal of Endocrinology (1994) 140, 475–482

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