Endometrial mRNA expression of oestrogen receptor α, progesterone receptor and insulin-like growth factor-I (IGF-I) throughout the bovine oestrous cycle

Abstract The effects of various hormones commonly added to hepatocyte culture media upon the expression of the GH receptor (GHR) and insulin-like growth factor-I (IGF-I) genes in cultured porcine hepatocytes were investigated. Preliminary investigations indicated that there was an absolute requirement only for insulin, with high losses of cell viability upon long term exclusion of insulin from the culture medium. The decline in GHR expression with time in culture was found to be less when high levels of glucose were included in the medium. Therefore the basal culture medium used in these studies was Williams' medium E supplemented with 0·2% (w/v) BSA, 5000 mg glucose/l and 100 nmol porcine insulin/l. The addition of dexamethasone (100 nmol/l) increased the expression of both GHR and IGF-I (class 1 transcripts only) mRNA (P<0·001 and P<0·05 respectively), and resulted in an increased responsiveness of IGF-I mRNA expression to GH (1 μg/ml), when the two were added in combination (although only class 1 transcripts were shown to be statistically significant, P<0·01). The addition of either thyroid hormone (1 nmol/l T3 or T4) alone also increased the expression of GHR mRNA (P<0·01) in addition to the dexamethasone stimulated expression, with T4 appearing to decrease IGF-I expression slightly (P<0·05) (either on its own or with T3). As with dexamethasone, the thyroid hormones increased the response of IGF-I mRNA expression to GH (1 μg/ml) when added in combination with GH (P<0·001). These observations demonstrate one possible mechanism for the interactions of glucocorticoids and thyroid hormones with the GH–IGF axis. Journal of Endocrinology (1995) 146, 239–245

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Steroidogenic responses of pig corpora lutea to insulin-like growth factor I (IGF-I) throughout the oestrous cycle

Reproduction ◽

10.1530/rep.0.1250241 ◽

2003 ◽

pp. 241-249 ◽

Cited By ~ 14

Author(s):

EA Miller ◽

Z Ge ◽

V Hedgpeth ◽

JE Gadsby

Keyword(s):

Signal Transduction ◽

Growth Factor ◽

Oestrous Cycle ◽

Corpora Lutea ◽

Insulin Like Growth Factor ◽

Luteal Cells ◽

Factor I ◽

Progesterone Secretion ◽

Igf I ◽

Growth Factor I

This study was designed to investigate the roles of insulin-like growth factor I (IGF-I), IGF-type I receptor (IGF-IR) and IGF-binding proteins (IGFBPs) in regulating progesterone secretion by pig corpora lutea during the oestrous cycle, and the signal transduction pathways involved in mediating the steroidogenic actions of IGF-I. Corpora lutea were collected on days 4, 7, 10, 13 and 15 or 16 of the oestrous cycle, enzyme dissociated and the luteal cells were cultured for 24 h in Medium 199 with IGF-I (0-100 ng ml(-1)), long R(3)-IGF-I (0-100 ng ml(-1)), anti-IGF-I (Sm 1.2B; 0-10 microg ml(-1)), anti-IGF-IR (alphaIR3; 0-2 microg ml(-1)), or IGF-I signal transduction pathway inhibitors (phosphatidylinositol (PI)-3-kinase: 100 nmol Wortmannin l(-1) and 10 micromol LY 294002 l(-1); MAP kinase: 50 micromol PD 98059 l(-1)) to investigate their effects on IGF-I (100 ng ml(-1)) stimulated progesterone secretion. Pig luteal cells displayed dose-dependent responses to IGF-I and long R(3)-IGF-I on days 4 and 7 of the oestrous cycle, but not on days 10-16. There was no difference in the ED(50) or V(max) (maximal response) values between IGF-I and long R(3)-IGF-I. Neither anti-IGF-I nor anti-IGF-IR had significant effects on progesterone secretion, at any dose or day. Wortmannin and LY 294002 blocked IGF-I stimulated progesterone secretion, but PD 98059 was without effect. Finally, IGF-I (6 microg) infused into the ovary on day 7 in vivo significantly increased progesterone secretion within 45 min of infusion. The conclusions of this study are: (1) IGF-I has steroidogenic actions only on 'young' (days 4-7) pig corpora lutea; (2) endogenous IGF-I and IGFBP are insufficient to modulate progesterone secretion in vitro; and (3) the steroidogenic actions of IGF-I are mediated via PI-3-kinase.

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Insulin-like growth factor I (IGF-I) mRNA expression in coho salmon, Oncorhynchus kisutch: Tissue distribution and effects of growth hormone/prolactin family proteins

Fish Physiology and Biochemistry ◽

10.1007/bf00004587 ◽

1993 ◽

Vol 11 (1-6) ◽

pp. 371-379 ◽

Cited By ~ 89

Author(s):

Cumming Duan ◽

Stephen J. Duguay ◽

Erika M. Plisetskaya

Keyword(s):

Growth Hormone ◽

Growth Factor ◽

Tissue Distribution ◽

Mrna Expression ◽

Coho Salmon ◽

Oncorhynchus Kisutch ◽

Insulin Like Growth Factor ◽

Factor I ◽

Igf I ◽

Growth Factor I

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Insulin-like growth factor I messenger ribonucleic acid expression in porcine thyroid follicles is regulated by thyrotropin and iodine

Acta Endocrinologica ◽

10.1530/eje.0.1320605 ◽

1995 ◽

Vol 132 (5) ◽

pp. 605-610 ◽

Cited By ~ 20

Author(s):

Lorenz C Hofbauer ◽

Michael Rafferzeder ◽

Onno E Janssen ◽

Roland Gärtner

Keyword(s):

Growth Factor ◽

Mrna Expression ◽

Ribonucleic Acid ◽

Cdna Probe ◽

Northern Hybridization ◽

Insulin Like Growth Factor ◽

Messenger Ribonucleic Acid ◽

Factor I ◽

Igf I ◽

Growth Factor I

Hofbauer LC, Rafferzeder M, Janssen OE, Gartner R. Insulin-like growth factor I messenger ribonucleic acid expression in porcine thyroid follicles is regulated by thyrotropin and iodine. Eur J Endocrinol 1995;132:605–10. ISSN 0809–4643 Insulin-like growth factor I (IGF-I) has been shown to be released from thyrocytes in vitro. We investigated IGF-I mRNA expression during treatment with thyrotropin (TSH), forskolin and potassium iodide (KI) in intact porcine thyroid follicles ex vivo. Porcine thyroid follicles were prepared by collagenase digestion and cultured in the presence of TSH, forskolin or KI. After different incubation times, mRNA was isolated and examined by Northern hybridization with a porcine IGF-I cDNA probe of 405 bp in length. In untreated follicles no IGF-I mRNA was found, whereas in follicles stimulated with TSH an IGF-I mRNA of 7.0 kb was detected after 24 h, which persisted for another 24 h. Forskolin treatment mimicked the TSH effect, indicating that IGF-I mRNA expression may be stimulated by the adenylate cyclase pathway. Preincubation of the porcine follicles with KI decreased dose dependently the TSH-induced IGF-I mRNA expression, with complete inhibition at 10 μmol/l KI. These results suggest that TSH acts via the cAMP pathway to enhance IGF-I mRNA expression, which then may lead to an autocrine IGF-I stimulation. The IGF-I mRNA expression is under negative control of iodide. Roland Gärtner, Medizinische Klinik, Ludwig Maximilians University, Ziemssenstrasse 1, 80336 München, Germany

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