Serum Immunoreactive Somatomedin Levels in Normal Adults, Pregnant Women at Term, Children at Various Ages, and Children with Constitutionally Delayed Growth*

Bala, R. M.; Lopatka, J E; Leung, Alice; McCoy, Ernest E.; McArthur, Robert G.

doi:10.1210/jcem-52-3-508

Cited by 193 publications

(77 citation statements)

References 29 publications

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“…The pattern obtained in this study was similar to the pubertal IGF-I surge reported in humans and rats [14,15], although this was not clear in previous studies of Meishan boars [16,17]. Such a change has not been reported in E u r o p e a n b r e e d s , s o t h i s c h a n g e m a y b e characteristic of Meishan pigs.…”

Section: Discussionsupporting

confidence: 79%

Age-related Changes of Reproductive Hormones in Young Meishan Boars

Kanematsu

Wei

Watanabe

et al. 2006

Journal of Reproduction and Development

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Abstract. Meishan pigs are known for their early sexual maturity. On the other hand, they grow slowly. There is no information currently available about the combination of these two characteristics in Meishan pigs. To study the developmental characteristics of Meishan pigs, the plasma concentrations of LH, FSH, inhibin, testosterone, estradiol-17β, progesterone and insulin-like growth factor-I (IGF-I) in young Meishan boars were determined using RIA and ELISA. Inhibin decreased with age in weeks, while testosterone and estradiol-17β increased. Testosterone increased gradually, and an increase in estradiol-17β occurred after sexual maturity. IGF-I increased before puberty and subsequently decreased just after puberty like a pubertal IGF-1 surge. FSH, LH and progesterone did not change with age. There was no significant correlation among the hormones. During the experimental period, the Meishan boars showed large individual differences. These differences may depend on the fact that Meishan boar reach maturity at 12 weeks of age and continue to grow thereafter.

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Section: Discussionsupporting

confidence: 79%

Age-related Changes of Reproductive Hormones in Young Meishan Boars

Kanematsu

Wei

Watanabe

et al. 2006

Journal of Reproduction and Development

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“…The preferential induction of adrenocortical androgen secretion by IGFs is probably based on their predominant and direct stimulation of the 17 -hydroxylase/17,20-lyase (P450c17) expression, which is a key enzyme of androgen biosynthesis (L'Allemand et al 1996, Kristiansen et al 1997. Since the onset of adrenarche is characterized by a relative increase in P450c17 activity and coincides with an increase in IGF-I serum levels (Bala et al 1981), it is tempting to speculate that the IGF system may be involved in the developmental regulation of adrenal androgen secretion. Furthermore, activation of the IGF-I receptor by IGFs or high levels of circulating insulin has been implicated in the pathogenesis of various states of hyperandrogenemia such as polycystic ovary syndrome (Barbieri et al 1986).…”

Section: Discussionmentioning

confidence: 99%

Regulation of steroidogenesis by insulin-like growth factors (IGFs) in adult human adrenocortical cells: IGF-I and, more potently, IGF-II preferentially enhance androgen biosynthesis through interaction with the IGF-I receptor and IGF-binding proteins

Fottner¹,

Engelhardt²,

Weber³

1998

Journal of Endocrinology

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Although the effect of insulin-like growth factors (IGFs) in fetal adrenocortical cells has been investigated extensively, the role of the IGF system in the adult human adrenal gland remains unclear. In the present study we investigated the effect of recombinant human IGF-I and IGF-II on cortisol, dehydroepiandrosterone sulfate (DHEA-S) and cAMP synthesis in adult human adrenocortical cells in primary culture. Both IGFs stimulate basal as well as adrenocorticotropin (ACTH)-induced steroid secretion in a time-and dose-dependent fashion. While both IGFs (6·5 nM) induced only a moderate 2-fold increase in basal cortisol output after 48 h, the effect on basal DHEA-S secretion was significantly stronger, with a 2·7-and 3·7-fold stimulation by IGF-I and IGF-II respectively. Similarly, IGF-II enhanced ACTH-induced cortisol and DHEA-S secretion more potently than IGF-I. In doseresponse experiments, the maximum stimulation of ACTH-induced DHEA-S secretion was induced by 1·6 nM IGF-I (2-fold increase) or IGF-II (2·9-fold increase), while the maximum response of cortisol secretion was elicited only at 13 nM IGF-I (2-fold increase) or IGF-II (2·5-fold increase). This resulted in a significant shift of the DHEA-S dose-response curves to the left, indicating a relative selective stimulation of androgen biosynthesis by physiologically low concentrations (0·4-3·2 nM) of IGF-II, and less potently by IGF-I. At all doses tested, the steroidogenic effect of IGF-II was significantly stronger than the effect of IGF-I. Although both IGF receptors are present in adult human adrenocortical cells, the steroidogenic effect of IGF-II is mediated through the IGF-I receptor, since [Arg 54,55 ]IGF-II, which only binds to the IGF-I receptor, was equipotent with native IGF-II, whereas [Leu 27 ]IGF-II, which preferentially binds to the type II IGF receptor, did not show any effect. In addition, [des 1-3 ]IGF-I, which exhibits only minimal binding to IGFBPs, was significantly more potent than native IGF-I in stimulating adrenal steroid biosynthesis, and elicited almost the same maximum stimulatory effect as IGF-II and [des [1][2][3][4][5][6] ]IGF-II. By Western ligand blotting of conditioned medium it was shown that adult human adrenocortical cells secrete various IGF-binding proteins (IGFBPs), which are induced differentially by treatment with ACTH. In conclusion, these results demonstrate that: (1) IGF-II stimulates basal as well as ACTH-induced DHEA-S and cortisol secretion from adult human adrenocortical cells more potently than IGF-I; (2) both IGFs predominantly stimulate androgen biosynthesis; (3) the steroidogenic effect of IGF-I and IGF-II is mediated through interaction with the IGF-I receptor; (4) the different steroidogenic potency of IGF-I and IGF-II might be explained by interaction of these ligands with locally produced IGFBPs. These data indicate that the IGF system plays an important role in the regulation of the differentiated function of adult human adrenocortical cells.

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“…The pattern of IGF-I development from childhood to adult life has been more consistently established (8,12,26). Although the methodologies are still evolving, the plasma IGF-I concentration typically increases with age in young children (>10.3 nM or 80 /Lg/L) with a prominent surge (>51 nM or 400 /LgIL) at puberty (20,27).…”

Section: Discussion Table 4 Correlation Of Individual Concentrationsmentioning

confidence: 99%

“…Although the methodologies are still evolving, the plasma IGF-I concentration typically increases with age in young children (>10.3 nM or 80 /Lg/L) with a prominent surge (>51 nM or 400 /LgIL) at puberty (20,27). Thereafter, plasma IGF-I declines steadily until normal adult values are reached (12,25). After 40 y of age, IGF-I declines again to levels lower than in early adulthood (26).…”

Section: Discussion Table 4 Correlation Of Individual Concentrationsmentioning

confidence: 99%

“…IGFBP-3 can exhibit either an inhibitory (4) or a potentiating (5) effect on IGF-I bioactivity in vitro, depending on its ability to alter the equilibrium between IGF-I and its receptor (5). Although IGF-I is thought to play an important role in postnatal growth (6)(7)(8)(9)(10)(11)(12)(13)(14)(15), there is disagreement among authors (16)(17)(18)(19) about the effects of postnatal age on plasma IGF-I in early infancy. The usefulness of obtaining plasma IGF-I concentrations in infancy is limited because normal values for this age group have not been established.…”

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confidence: 99%

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Insulin-Like Growth Factor (IGF)-I and IGF-Binding Protein 3 during the First Year in Term and Preterm Infants

et al. 1995

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Plasma IGF-I and IGF-binding protein 3 (IGFBP-3) were determined by radioimmunoassay in term infants (n = 51) at 0, 2,4, 6, and 12 mo and preterm infants (n = 51) at -3 (28.4 wk postconceptional age), -2, -1.5, -1,0,2,4,6,9, and 12 rna from expected term. The effects of gestational age at birth (term or preterm) and study age were determined by repeated measures analysis of variance and Fisher's least squares difference. In preterm infants, IGF-I increased between -3 and 2 mo from 0.75 to 10.4 nM, decreased between 2 and 9 mo to 7.3 nM, and increased again between 9 and 12 mo to 10.1 nM (p < 0.0001), whereas IGFBP-3 increased relatively little from -3 to 0 rna (14.2 to 30.2 nM, p < 0.05) and plateaued from 2 to 12 mo (49.8 to 62.3 nM). At 0 rna, IGF-I and IGFBP-3 were the same in term and preterm infants, but preterm infants had higher IGF-I from 2 IGF mediate the growth-promoting actions of growth hormone in regulating the proliferation and differentiation of different cell types (1). These polypeptides which are structurally homologous to insulin also exert insulin-like metabolic effects. Both these effects are mediated through target cell surface receptors (2). Most tissues in the body produce IGF, and they are present in serum mostly bound to specific high molecular weight binding proteins (3). Of the six IGFBP that have been identified so far, IGFBP-3 is the major form present in the serum (1, 2) and demonstrates a high affinity for both IGF-I and IGF-II. IGFBP-3 can exhibit either an inhibitory (4) or a potentiating (5) effect on IGF-I bioactivity in vitro, depending on its ability to alter the equilibrium between IGF-I and its receptor (5).

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Serum Immunoreactive Somatomedin Levels in Normal Adults, Pregnant Women at Term, Children at Various Ages, and Children with Constitutionally Delayed Growth*

Cited by 193 publications

References 29 publications

Age-related Changes of Reproductive Hormones in Young Meishan Boars

Age-related Changes of Reproductive Hormones in Young Meishan Boars

Regulation of steroidogenesis by insulin-like growth factors (IGFs) in adult human adrenocortical cells: IGF-I and, more potently, IGF-II preferentially enhance androgen biosynthesis through interaction with the IGF-I receptor and IGF-binding proteins

Insulin-Like Growth Factor (IGF)-I and IGF-Binding Protein 3 during the First Year in Term and Preterm Infants

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