Release of insulin-like growth factor I by the sheep placenta in vitro

1991 ◽  
Vol 3 (4) ◽  
pp. 379 ◽  
Author(s):  
J Falconer ◽  
JJ Davies ◽  
HP Zhang ◽  
R Smith
Keyword(s):  
Molecular Weight ◽  
Growth Factor ◽  
Binding Protein ◽  
Basal Plate ◽  
Gel Chromatography ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I ◽  
Villous Tissue

This study has utilized a tissue perifusion system to examine the release of insulin-like growth factor I (IGF I) from different regions of the sheep placenta at two stages of gestation. Placentae were obtained from ewes at either 116 +/- 7 (mean +/- s.e.) or 144 +/- 1.5 days of gestation and separated into the maternal basal plate or chorionic villous tissue. At both ages, the maternal basal plate tissue released approximately three times more IGF I than the chorionic villous tissue. No difference was found between the rate of release of IGF I from the maternal basal plate at 120 and 140 days of gestation, whereas the chorionic villous tissue released less IGF I later in gestation. Maternal basal plate tissue was less responsive to a depolarizing dose of KCl than was chorionic villous tissue at either age. After acid gel chromatography, perfusate from the basal plate had three peaks of IGF immunoreactivity (corresponding to binding protein, IGF I and a form with an intermediate molecular weight). In contrast, the chorionic villous tissue released only a form with a high molecular weight, corresponding to binding protein. These results demonstrate that the sheep placenta produced IGF I, that secretion varies between different placental zones which contain different cell types and that there are maturational changes in placental IGF I secretion. The IGFs may be involved in placental growth.

Improved estimates of clearance of 131I-labelled insulin-like growth factor-I carrier protein complexes from blood plasma of sheep

1989 ◽  
Vol 123 (3) ◽  
pp. 469-475 ◽  
Author(s):  
S. R. Davis ◽  
S. C. Hodgkinson ◽  
L. G. Moore ◽  
P. D. Gluckman
Keyword(s):  
Molecular Weight ◽  
Growth Factor ◽  
Half Life ◽  
Binding Protein ◽  
Free Form ◽  
High Molecular Weight Fraction ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

ABSTRACT Clearance of protein-bound forms of insulin-like growth factor-I (IGF-I) from the circulation of sheep was determined using single injections of 131I-labelled ovine or [Thr59]-human IGF-I, in the 'free' form or prebound to 50 or 150 kDa plasma binding protein fractions. The half-life of circulating protein-bound forms of IGF-I was determined by size-exclusion chromatography of plasma samples taken over a 24-to 26-h experimental period. IGF-I bound to lower molecular weight binding protein(s) (approximately 50 kDa) showed a half-life of 26–40 min (mean 34 min; n = 6), while the half-life of a high molecular weight fraction (150 kDa) was considerably longer (range 398–603 min; mean 545 min; n =8). Metabolic clearance of IGF-I following administration of free tracer ranged from 3.0 to 5.3 ml/min in sheep (n = 4) weighing 26.0–28.5 kg. Tracer distribution volume was 59 ml/kg liveweight (n=4). Tracer degradation products were first detected in plasma 8 h after i.v. administration. No differences in stability of the purified ovine and recombinant human IGF-I tracer preparations were observed. However, a fraction of the [Thr59]-IGF-I tracer did not possess binding activity and this was associated with excretion of a greater proportion of administered radioactivity (over 22 h) in urine in animals receiving [Thr59]-IGF-I tracer (18.4–19.3%) compared with ovine IGF-I (7.1–11.0%). Following administration of free tracer or tracer bound to the 50 kDa protein, the proportion of radioactivity bound to the 150 kDa fraction increased over the first 20-30 min of observation. However, this was not apparent following administration of tracer bound to the 150 kDa protein, indicating that the more rapid turnover of IGF-I bound to the 50 kDa protein was associated, in part, with transfer of IGF-I to the 150 kDa binding protein fraction. The calculated secretion rates of the IGFs were two- to threefold and twentyfold higher, for IGF-I and -II respectively, relative to that of insulin. These data are evidence supporting roles for IGFs in the regulation of metabolism. Journal of Endocrinology (1989) 123, 469–475

Colocalization of insulin-like growth factor-binding protein with insulin-like growth factor I

1991 ◽  
Vol 261 (1) ◽  
pp. F22-F28 ◽  
Author(s):  
S. Kobayashi ◽  
D. R. Clemmons ◽  
M. A. Venkatachalam
Keyword(s):  
Growth Factor ◽  
Cultured Cells ◽  
Binding Protein ◽  
Insulin Like Growth Factor ◽  
Intense Staining ◽  
Factor Binding ◽  
Factor I ◽  
Collecting Ducts ◽  
Igf I ◽  
Growth Factor I

We report the localization of insulin-like growth factor I (IGF-I) and a 25-kDa form of insulin-like growth factor-binding protein (IGF-BP-1) in adult rat kidney. The antigens were localized using a rabbit anti-human IGF-I antibody, and a rabbit anti-human IGF-BP-1 antibody raised against human 25-kDa IGF-BP-1 purified from amniotic fluid. Immunohistochemistry by the avidin-biotin peroxidase conjugate technique showed that both peptides are located in the same nephron segments, in the same cell types. The most intense staining was in papillary collecting ducts. There was moderate staining also in cortical collecting ducts and medullary thick ascending limbs of Henle's loop. In collecting ducts the antigens were shown to be present in principal cells but not in intercalated cells. In distal convoluted tubules, cortical thick ascending limbs, and in structures presumptively identified as thin limbs of Henle's loops there was only modest staining. The macula densa, however, lacked immunoreactivity. Colocalization of IGF-I and IGF-BP-1 in the same cells supports the notion, derived from studies on cultured cells, that the actions of IGF-I may be modified by IGF-BPs that are present in the same location.

scholarly journals Insulin, Insulin-Like Growth Factor I (IGF-I), IGF-Binding Protein-1, Growth Hormone, and Feeding in the Newborn

1998 ◽  
Vol 83 (10) ◽  
pp. 3550-3557 ◽  
Author(s):  
A. L. Ogilvy-Stuart ◽  
S. J. Hands ◽  
C. J. Adcock ◽  
J. M. P. Holly ◽  
D. R. Matthews ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Binding Protein ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Igf Binding ◽  
Growth Factor I ◽  
Igf Binding Protein

SERUM INSULIN-LIKE GROWTH FACTOR-I (IGF-I) AND IGF BINDING PROTEIN (BP)-1, -3 ADAPTATIONS TO TRAINING

1998 ◽  
Vol 30 (Supplement) ◽  
pp. 173
Author(s):  
R. C. Hickson ◽  
L. P. Koziris ◽  
R. T. Chatterton ◽  
R. T. Groseth ◽  
J. M. Christie ◽  
...  
Keyword(s):  
Growth Factor ◽  
Binding Protein ◽  
Serum Insulin ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Igf Binding ◽  
Growth Factor I ◽  
Igf Binding Protein
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