The growth hormone–insulin like growth factor axis in pregnancy

The growth hormone (GH)–insulin-like growth factor (IGF) axis is one of the main drivers of mammalian growth and development. Pituitary secretion of GH is pulsatile and under positive and negative hypothalamic control, as well as stimulation from gastric-secreted acyl-ghrelin. GH has anabolic and metabolic effects both directly via the GH-receptor (GHR) and indirectly via stimulation of IGF1 production at multiple target tissues. In this review, we describe the major changes to this axis during pregnancy, with increasing GH abundance in the maternal circulation across multiple species. This stimulates secretion of IGFs, whose bioavailability is also increased by proteolytic cleavage of their circulating binding proteins during pregnancy. These changes in turn induce maternal metabolic adaptations to pregnancy and promote placental function and fetal growth, as does exogenous GH or IGF treatment in animal models of normal and compromised pregnancy. Finally, we explore alternative approaches to enhance maternal GH abundance during pregnancy to promote maternal adaptations, placental function and hence fetal growth.

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A Longitudinal Study of Intrauterine Growth and the Placental Growth Hormone (GH)-Insulin-Like Growth Factor I Axis in Maternal Circulation: Association between Placental GH and Fetal Growth

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2003-030282 ◽

2004 ◽

Vol 89 (1) ◽

pp. 384-391 ◽

Cited By ~ 120

Author(s):

M. Chellakooty ◽

K. Vangsgaard ◽

T. Larsen ◽

T. Scheike ◽

J. Falck-Larsen ◽

...

Keyword(s):

Growth Hormone ◽

Longitudinal Study ◽

Growth Factor ◽

Fetal Growth ◽

Insulin Like Growth Factor ◽

Maternal Circulation ◽

Intrauterine Growth ◽

Factor I ◽

Placental Growth Hormone ◽

Growth Factor I

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Effects of growth hormone-releasing factors and cottonseed meal on hormones and metabolites in plasma from lambs fed lucerne chaff ad libitum

Australian Journal of Agricultural Research ◽

10.1071/ar9941125 ◽

1994 ◽

Vol 45 (6) ◽

pp. 1125 ◽

Cited By ~ 2

Author(s):

RD Sainz ◽

BJ Hosking ◽

FJ Hart ◽

GSG Spencer

Keyword(s):

Fatty Acids ◽

Growth Hormone ◽

Growth Factor ◽

Cottonseed Meal ◽

Metabolic Effects ◽

Insulin Like Growth Factor ◽

Plasma Urea ◽

Blood Samples ◽

Esterified Fatty Acids ◽

Ad Libitum

This study was part of an experiment on the effects of cottonseed meal (CSM) and growth hormone-releasing factor (GRF) on growth in lambs fed lucerne chaff. Forty-eight crossbred lambs were fed lucerne chaff ad libitum, alone or with a cottonseed meal supplement (CSM; 300 g/day). Eight lambs from each group were injected twice daily with recombinant or synthetic GRF (rGRF and sGRF respectively; 30 8g per kg body weight/day) or excipient only for 28 or 30 days. Jugular blood samples were obtained on days 0, 7, 14, 21 and 28. On day 29, blood samples were taken from selected lambs (n = 2/group) at 0, 20, 40, 60, 80, 100, 120, 160 and 240 min after injection. Supplementation of lucerne chaff with CSM generally increased glucose and urea concentrations in plasma, reflecting improved energy and protein status. However, concentrations of growth hormone, insulin-like growth factor-1 and insulin were unaffected by CSM, as were plasma proteins, triacylglycerols and non-esterified fatty acids. Injection of rGRF and sGRF stimulated secretion of growth hormone (GH), insulin-like growth factor-1 (IGF-1) and insulin. Peak GH concentrations (20 min) following injection of GRF appeared to be higher in lambs fed CSM than in those receiving lucerne chaff alone. In contrast, maximal concentrations of IGF-1 were seen after 14 days of treatment. These changes were accompanied by increased plasma glucose, with no changes in triacylglycerols, non-esterified fatty acids and protein. Plasma urea was reduced by GRF, indicating that amino acids were diverted away from catabolism towards protein synthesis. These two sources of GRF were very similar in their endocrine and metabolic effects. This confirms similar observations regarding their effects on growth performance and carcass composition.

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