scholarly journals The expression of the IGF family and GH receptor in the bovine mammary gland

2001 ◽  
Vol 168 (1) ◽  
pp. 39-48 ◽  
Author(s):  
A Plath-Gabler ◽  
C Gabler ◽  
F Sinowatz ◽  
B Berisha ◽  
D Schams
Keyword(s):  
Mammary Gland ◽  
Binding Proteins ◽  
Mammary Development ◽  
Mammary Tissue ◽  
Bovine Mammary Gland ◽  
Igf Binding Proteins ◽  
Gh Receptor ◽  
Igf I ◽  
Temporal Expressions ◽  
Igfbp 3

To study the involvement of the IGFs in mammary development and lactation of the cow, the temporal expressions of IGF-I and -II, its receptor type 1 (IGFR-1), IGF-binding proteins (IGFBPs)-1 to -6 and GH receptor (GHR) mRNA were examined. This was carried out for different stages of mammogenesis, lactogenesis, galactopoiesis and involution in the bovine mammary gland of 26 animals. Furthermore, IGF-I was localised by immunohistochemistry. The highest mRNA concentrations for IGF-I were detected in the mammary tissue of late pregnant heifers (days 255-272) and significantly lower expression was detected during lactogenesis and galactopoiesis. Immunohistochemistry of IGF-I revealed only a weak staining in the epithelium of the ducts during mammogenesis. The epithelium of the alveoli were negative during mammogenesis, lactogenesis and galactopoiesis but displayed distinct IGF-I activity during involution. In the stroma a distinct staining of the cytoplasm of adipocytes and of vascular smooth muscle cells was observed. A certain percentage of fibroblasts (usually 20-30%) were also immunopositive. In contrast, highest expression for IGFR-1 was detected during galactopoiesis and involution. The lowest mRNA concentration for IGFR-1 was found during pregnancy (days 194-213). In general, the expression of IGF-II was not regulated during mammogenesis and lactation, but decreased during involution. The mRNA for the six binding proteins was detected in the bovine mammary gland. The dominant binding proteins were IGFBP-3 and -5. The highest expression of IGFBP-3 was observed during mid-pregnancy and the lowest during late lactation, involution and in non-pregnant heifers. The mRNA for IGFBP-5 increased during late mammogenesis and lactogenesis followed by a decrease thereafter. In general, the mRNA concentrations for IGFBP-2, -4 and -6 were barely detectable during all stages. In contrast, the expression for IGFBP-1 was upregulated in the mammary gland of virgin heifers and increased around the onset of lactation. mRNA for GHR was found during all stages examined without outstanding fluctuations. In conclusion, locally produced IGF-I and -II may mediate mammogenesis. The high mammary IGFR-1 mRNA during lactation suggests a role for peripheral IGF-I in maintenance of lactation. The role of IGFBPs in the mammary gland needs further evaluation.

Investigation into the potential physiological sources of rat milk IGF-I and IGF-binding proteins

1995 ◽  
Vol 145 (3) ◽  
pp. 569-578 ◽  
Author(s):  
S M Donovan ◽  
R L Hintz ◽  
R G Rosenfeld
Keyword(s):  
Binding Proteins ◽  
De Novo ◽  
Northern Analysis ◽  
Mammary Tissue ◽  
Maternal Circulation ◽  
Igf Binding Proteins ◽  
Variable Expression ◽  
Igf I ◽  
Igf Binding ◽  
Igfbp 3

Abstract We have previously reported the presence of IGF-I and IGF-binding proteins (IGFBP-2, -3 and -4) in rat milk. Herein, the potential sources of rat milk IGF-I and IGFBPs were investigated. Lactating dams (day 14 postpartum) were separated from their pups and injected intraperitoneally with 0·45 μCi 125I-IGF-I or 125I-IGFBP-3. After 3 h, serum and milk of rats receiving 125I-IGF-I contained 7642 ± 3121 and 14 455 ± 7837 c.p.m./ml respectively. Serum and milk of rats given 125I-IGFBP-3 contained 7232 ± 1366 and 10 371 ± 4091 c.p.m./ml respectively. Sephacryl S-200 gel filtration chromatography demonstrated that the 125I-IGF-I in both serum and milk was primarily in the 150 kDa IGF-binding complex, whereas the distribution of 125I-IGFBP-3 differed between serum and milk. In serum, most of the 125I-IGFBP-3 was in the 150 kDa fraction, while most 125I-IGFBP-3 in milk was in the 40 kDa fraction. Northern analysis of liver showed IGFBP-1 and -3 mRNA expression, with variable expression of IGFBP-2 and -4 mRNA. In contrast, mammary tissue expressed only IGFBP-2 and -4 mRNA, suggesting that these IGFBPs in milk may arise from de novo synthesis within the mammary gland. The lack of detectable IGFBP-3 mRNA in mammary tissue and the translocation of 125I-IGFBP-3 from the serum suggest that milk IGFBP-3 arises from the maternal circulation. Journal of Endocrinology (1995) 145, 569–578

scholarly journals Effect of chronic thyroxine treatment on IGF-I, IGF-II and IGF-binding protein expression in mammary gland and liver during pregnancy and early lactation in rats

2002 ◽  
pp. 729-739 ◽  
Author(s):  
R Rosato ◽  
D Lindenbergh-Kortleve ◽  
J Neck ◽  
S Drop ◽  
G Jahn
Keyword(s):  
Mammary Gland ◽  
Binding Protein ◽  
Mammary Development ◽  
Mammary Tissue ◽  
Mrna Levels ◽  
Liver Growth ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

OBJECTIVE: Hyperthyroidism in rats produces organ hypertrophy and increases in circulating IGF-I and IGF-binding protein (IGFBP)-3. Chronic treatment with thyroxine (T(4)) during pregnancy advances parturition, blocks lactation and changes several hormone receptors in mammary gland and liver. Since IGFs are implicated in mammary and liver growth and in differentiation, we studied the effects of hyperthyroidism, induced by daily injections of T(4) (0.25 mg/kg). DESIGN AND METHODS: Using quantitative RT-PCR and in situ hybridization, the gene expression of IGF-I, IGF-II and the IGFBPs was determined in mammary gland and liver of rats at estrus and days 7, 14 and 21 of pregnancy (G7, G14, G21), day 1 postpartum (L1) and 3 days after removing the litter (L4). Circulating levels of IGF-I, tri-iodothyronine (T(3)), PRL and GH were measured. RESULTS: T(4) treatment (HT) increased circulating T(3) save on G21, did not change serum IGF-I, increased PRL on G21 and decreased GH on L1. PRL decreased on L1 because of the absence of lactation. Hepatic IGF-I mRNA was low during pregnancy and increased on L4. HT advanced this increase to L1. In controls, liver IGFBP-3 mRNA levels decreased from G14 to G21, whereas IGFBP-4 showed an inverse pattern. HT lowered IGFBP-3 mRNA and increased IGFBP-4. Increases in mammary concentrations of IGF-I, IGFBP-3 and IGFBP-4 mRNAs were seen on G21. HT delayed these peaks to L1. Mammary IGF-II and IGFBP-2 mRNA levels were high on G7 and G14, and fell afterwards, with HT having no effects. IGFBP-5 mRNA decreased during pregnancy and increased on L1. HT increased IGFBP-5 levels in early pregnancy and on L1. IGF-I mRNA localized to connective and epithelial mammary tissue, while IGFBP-2 and IGFBP-5 mRNA was only in epithelial cells. CONCLUSION: These results imply a role for IGF-I, IGFBP-3 and IGFBP-4 in terminal mammary development, while IGF-II and IGFBP-2 may be implicated in early growth. IGFBP-5 has been implicated in mammary apoptosis, and the HT-induced increase may play a role in the premature mammary involution of the HT rats.

Measurement of Human Igf-II Using Sephacryl Extraction: A Rapid and Reliable Assay Method

1996 ◽  
Vol 33 (3) ◽  
pp. 201-208 ◽  
Author(s):  
Barbara H Mason ◽  
Michele A Tatnell ◽  
Ian M Holdaway
Keyword(s):  
Growth Factor ◽  
Binding Proteins ◽  
Complete Removal ◽  
Assay Method ◽  
Insulin Like Growth Factor ◽  
Serum Concentrations ◽  
Igf Binding Proteins ◽  
Factor Ii ◽  
Igf I ◽  
Igfbp 3

Measurement of insulin-like growth factor II (IGF-II) in human serum is complicated by the presence of IGF binding proteins and usually involves cumbersome extraction procedures followed by radioimmunoassay. We have utilized an extraction process developed for measuring insulin-like growth factor II in ovine serum using Sephacryl HR100, and have applied this to the extraction of human samples followed by radioimmunoassay for human IGF-II. The assay yielded 98% recovery of unlabelled IGF-II, parallelism between dilutions of eluate and the standard curve, complete removal of binding proteins and near-complete removal of IGF-I, and intra- and interassay coefficients of variation of 5% and 9%, respectively. The normal range for serum IGF-II in women was 490–1056 μg/L, and IGF-II levels were positively correlated with serum concentrations of insulin-like growth factor binding protein-3 (IGFBP-3) but not with IGF-I levels. Mean serum concentrations of IGF-II were reduced below normal in a number of hypopituitary patients and children with short stature and IGF-II concentrations in these subjects correlated positively with IGF-I and IGFBP-3. In acromegalic patients IGF-II levels were usually normal and were negatively correlated with IGF-I concentrations. From our experience with the above results the present assay appears particularly suitable for clinical measurements and research projects where high sample throughput is required.

Circulating insulin-like growth factors (IGFs), IGF-binding proteins (IGFBPs) and tissue mRNA levels of IGFBP-2 and IGFBP-4 in the ovine fetus

1995 ◽  
Vol 145 (3) ◽  
pp. 545-557 ◽  
Author(s):  
J M Carr ◽  
J A Owens ◽  
P A Grant ◽  
P E Walton ◽  
P C Owens ◽  
...  
Keyword(s):  
Binding Proteins ◽  
Mrna Level ◽  
Common Factor ◽  
Late Gestation ◽  
Mrna Levels ◽  
Igf Binding Proteins ◽  
Fetal Sheep ◽  
Igf I ◽  
Igf Binding ◽  
Igfbp 3

Abstract The IGF-binding proteins (IGFBPs) are a family of at least six structurally related proteins, which bind the IGFs and modulate their actions, including the regulation of preand postnatal growth. In this study we have examined the relationship between circulating and tissue mRNA levels of IGFBPs and related this to circulating IGFs in the fetal sheep over the gestational period when rapid growth and development occurs. Circulating IGFBP-2, as measured by Western ligand blot (WLB), increases between early and mid gestation, remains high, then declines throughout late gestation (P=0·0002). Circulating IGFBP-3 increases throughout gestation, as measured by WLB or RIA (P=0·04 and P=0·0001 respectively), as does circulating IGFBP-4 (P=0·004). These ontogenic changes in circulating IGFBPs-2 and -4 are paralleled by changes in liver mRNA for these proteins and, for IGFBP-2, by those in kidney IGFBP-2 mRNA also. This suggests that liver and kidney may be the primary contributors to circulating IGFBP-2 and the liver to circulating IGFBP-4. IGFBP-2 mRNA is present in the heart and lung in early gestation but barely detectable in these tissues after approximately 60 days gestation. IGFBP-4 mRNA is also present in the heart in early but not late gestation, but is abundant in the lung throughout gestation. These results demonstrate tissue specific and developmental regulation of IGFBPs-2 and -4 at the mRNA level. To assess any role the circulating IGFs may play in mediating these changes in IGFBPs, or vice versa, both plasma IGF-I and IGF-II were measured by RIA. Circulating IGF-I increases as gestation progresses (P=0·0001), while circulating IGF-II increases between early and mid gestation, remains high (P=0·01), then declines. Circulating IGF-I is positively correlated with fetal weight (r=0·66, P=0·03), circulating IGFBP-3 (r=0·54, P=0·01) and IGFBP-4 (r=0·52, P=0·01). Circulating IGF-II positively correlates with circulating IGFBP-2 (r=0·48, P=0·02) throughout gestation and at 1 day postnatally. These relationships are consistent with circulating IGF-I influencing IGFBPs-3 and -4, and similarly, IGF-II determining IGFBP-2, or vice versa. Alternatively, these correlations may reflect coordinate regulation of IGF and IGFBP by a common factor. Journal of Endocrinology (1995) 145, 545–557

The insulin-like growth factors and their binding proteins in a case of non-islet-cell tumour-associated hypoglycaemia

1991 ◽  
Vol 131 (2) ◽  
pp. 303-311 ◽  
Author(s):  
A. M. Cotterill ◽  
J. M. P. Holly ◽  
S. C. Davies ◽  
V. J. Coulson ◽  
P. A. Price ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Islet Cell ◽  
Plasma Insulin ◽  
Binding Proteins ◽  
Late Pregnancy ◽  
Normal Serum ◽  
Systemic Effects ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Igfbp 3

ABSTRACT Non-islet-cell tumours which induce hypoglycaemia are rare. Insulin-like growth factor-II (IGF-II) produced by some tumours is thought to be responsible for the hypoglycaemia and other systemic effects, despite normal or even low serum IGF-II levels. We studied a 44-year-old woman presenting with symptomatic hypoglycaemia associated with a large intraabdominal haemangiopericytoma. The serum IGF-II level was 455 μg/l when measured after acid-ethanol extraction (normal range (NR) 450–750 μg/l) and 1063 μg/l after acid chromatography (normal human serum pool 1068 μg/l). Levels of fasting plasma insulin, C-peptide, glucose and serum IGF-I levels were low before the operation (< 2 mU/l (NR <2-14), 0·23 nmol/l (NR 0-4-1-2), 3-1 mmol/l, (NR 3-7-5-9) and 002 U/ml respectively). After tumour removal, the symptoms resolved rapidly and the patient made a full recovery. Secretion of both insulin and growth hormone was suppressed before the operation in response to a 75 g glucose meal and to an infusion of 100 μg GH-releasing hormone (GHRH) respectively in comparison with studies after the operation. Serum IGF-II levels 6 weeks and 12 weeks after the operation fell to 385 μg/1 (777 μg/1; acid chromatography) and 280 μg/1 (647 μg/1; acid chromatography) and serum IGF-I levels increased to 0-35 U/ml and 0-26 U/ml. Serum before the operation and tumour extract contained chiefly a large molecular weight precursor IGF-II (molecular weight 15 000–20 000) which disappeared from the serum after the operation. The IGF-binding proteins (IGFBP-1, IGFBP-2, IGFBP-3 and IGFBP-4) were examined. The preoperation fasting serum IGFBP-1 level was lower than expected (31 μg/l (NR 20–70 μg/l)) and similar to levels at 6 weeks after the operation (33 μg/l). This was surprising given the differences in plasma insulin levels before and after the operation (< 2 mU/l versus 13 mU/l). Using Western ligand blotting techniques, serum IGFBP-3 levels were found to be low and IGFBP-2 appeared to be the dominant IGFBP before the operation. Serum IGFBP-3 levels after the operation fell further. This further decrease appeared, in part, to be due to the presence of a cation-dependent IGFBP-3-specific protease which has previously only been described in late pregnancy. We conclude that in this subject, despite normal serum IGF-II levels, the hypoglycaemia and systemic effects on insulin and GH secretion were due to increased bioavailability of a circulating tumour-produced precursor form of IGF-II. This increased bioavailability appears to be due to alterations in the circulating levels and perhaps affinities of the IGFBPs. Journal of Endocrinology (1991) 131, 303–311

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

1991 ◽  
Vol 128 (2) ◽  
pp. 219-228 ◽  
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

Differential effects of GH stimulation on fasting and prandial metabolism and plasma IGFs and IGF-binding proteins in lean and obese sheep

1997 ◽  
Vol 154 (2) ◽  
pp. 329-346 ◽  
Author(s):  
J P McCann ◽  
S C Loo ◽  
D L Aalseth ◽  
T Abribat
Keyword(s):  
Binding Proteins ◽  
Binding Capacity ◽  
Plasma Concentrations ◽  
Whole Body ◽  
Daily Injection ◽  
Gh Treatment ◽  
Igf Binding Proteins ◽  
Igf I ◽  
Igf Binding ◽  
Igfbp 3

Abstract The effect of body condition per se on plasma IGFs and IGF-binding proteins (IGFBPs) and the whole-body metabolic responses to recombinant DNA-derived bovine GH (rbGH) in both the fed and the fasted state were determined in lean and dietary obese sheep (n=6/group). Sheep at zero-energy balance and equilibrium body weight were injected s.c. for 12 days with 100 μg/kg rbGH immediately before their morning feeding. Before GH treatment, fasting plasma concentrations of insulin (17·0 ± 1·9 vs 7·5 ± 0·7 μU/ml), IGF-I (345 ± 25 vs 248 ± 10 ng/ml), glucose (52·6 ± 1·1 vs 48·3 ± 0·7 mg/dl), and free fatty acid (FFA) (355 ± 45 vs 229 ± 24 nmol/ml) were greater (P<0·05) and those of GH (1·1 ± 0·2 vs 2·6 ± 0·3 ng/ml) were lower (P<0·05) in obese than in lean sheep. Fasting concentrations of IGF-II and glucagon were not affected (P>0·05) by obesity. GH concentrations were increased equivalently by 6–9 ng/ml in lean and obese sheep during GH treatment. GH caused an immediate and a marked fivefold increase in the fasting insulin level in obese sheep but only minimally affected insulin concentration in lean sheep. The increment in fasting glucose during GH treatment was greater (P<0·05) in obese (8–12 mg/dl) than in lean (2–5 mg/dl) sheep. Frequent measurements in the first 8 h after feeding and injection of excipient (day 0) or the first (day 1), sixth (day 6) and twelfth (day 12) daily injection of GH showed that prandial metabolism in both groups of sheep was affected minimally by GH. However, GH treatment on day 1 (not days 6 or 12) acutely attenuated the feeding-induced suppression of plasma FFA in both groups of sheep and this effect was significantly greater in obese than in lean sheep. Although obese sheep were hyposomatotropic, the basal and GH-induced increases in plasma IGF-I concentrations were greater (P<0·05) in obese than in lean sheep. Plasma IGF-II was unaffected by obesity and was not increased by GH stimulation. Western ligand blotting showed that IGFBP-3 accounted for approximately 50–60% of the plasma IGF-I binding capacity in sheep respectively both before and during GH treatment. Basal plasma levels of IGFBP-2 were lower (P<0·05) and those of IGFBP-3 greater (P<0·05) in obese compared with lean sheep. GH increased the level of IGFBP-3 equally in lean and obese sheep, but suppressed the expression of IGFBP-2 more (P<0·05) in lean than in obese sheep. We concluded that the diabetogenic-like actions of GH in sheep were exaggerated markedly by obesity, and were expressed more during the fasted than the fed states. The effects of GH stimulation on the endocrine pancreas may be selective for β-cells and preferentially enhanced by obesity. GH regulation of IGF-I and the IGFBPs differs in lean and obese sheep. Journal of Endocrinology (1997) 154, 329–346

scholarly journals Synthesis of the acid-labile subunit of the growth-hormone-dependent insulin-like-growth-factor-binding protein complex by rat hepatocytes in culture

1991 ◽  
Vol 275 (2) ◽  
pp. 441-446 ◽  
Author(s):  
C D Scott ◽  
R C Baxter
Keyword(s):  
Growth Hormone ◽  
Binding Proteins ◽  
Rat Hepatocytes ◽  
Alpha Subunit ◽  
Igf Binding Proteins ◽  
Rat Serum ◽  
Igf I ◽  
Igf Binding ◽  
Acid Labile ◽  
Igfbp 3

Insulin-like growth factors (IGFs) circulate predominantly in a growth-hormone-dependent ternary complex of 125-150 kDa. This study investigates the production of the alpha-subunit of this complex, an acid-labile glycoprotein without intrinsic IGF-binding activity, which binds to the IGF-binding protein IGFBP-3 in the presence of IGFs. Medium conditioned by primary cultures of rat hepatocytes produced alpha-subunit with similar complex-forming activity to purified rat serum alpha-subunit. Bovine growth hormone stimulated hepatocyte production of both IGF-I and alpha-subunit. IGF-I tracer bound to pure rat IGFBP-3 was converted from approx. 60 kDa to 150 kDa by serum alpha-subunit, whole rat serum or rat hepatocyte culture medium; this converting activity was destroyed by transient acidification. In contrast, IGF-I bound to hepatocyte-medium IGF-binding proteins could not be converted into a high-molecular-mass from by purified rat serum alpha-subunit. Rat serum and hepatocyte-medium alpha-subunit appeared identical by electrophoretic analysis, since reaction of either with cross-linked IGF-I.IGFBP-3 tracer resulted in bands of molecular mass 130 kDa and 160 kDa, probably representing intact and partially deglycosylated complexes. However, IGF-binding proteins in rat serum and hepatocyte medium were different, in that affinity labelling of medium binding proteins, depleted of endogenous IGFs, showed no evidence of the 50-60 kDa cluster of bands characteristic of rat serum IGFBP-3. We conclude that rat hepatocytes in primary culture produce alpha-subunit similar to that in rat serum; however, alpha-subunit is unable to form ternary complexes with hepatocyte IGF-binding proteins, since cultured hepatocytes do not secrete IGFBP-3.

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