Antagonism by growth hormone of insulin action in fetal sheep

Abstract

Insulin, glucose, lactate and alpha-amino acid nitrogen concentrations were measured in the plasma of ewes and their hypophysectomized fetal lambs during intravenous infusions of GH, prolactin or saline into the fetus in utero. Prolactin and saline had no effect on mother or fetus. Infusion of GH at 1.2 mg/kg per day for 2 days or at 0.4 mg/kg per day for 4 days caused a sustained twofold increae in the level of insulin and a smaller, but sustained, increase in the level of glucose in fetal plasma. We suggest that GH antagonizes the action of insulin in the fetus. Glucose supplies to the fetal brain and placenta may be protected by such antagonism of insulin use during glucose shortage.

Hypersomatotropism in the Dysmature Infant at Term and Preterm Birth

“…The stress-related increase in fetal-circu lating GH is likely to be of physiological sig nificance: GH is known to have insulinantagonizing actions on fetal carbohydrate [15] and lipid [16] metabolism, and GH receptors may be present in the placenta [17], In conclusion, although GH does not influence fetal-circulating IGF-1 levels [18,19] and is not essential for fetal growth [20], the present data further support the hypoth esis that GH plays a homeostatic role in the late-gestational fetus, particularly in the met abolic adaptation to conditions associated with subnormal intrauterine growth. …”

Growth hormone in Intra-uterine growth retarded newborns

“…19 The clinical impression that this excess consists mainly of fat is in line with experimental evidence attributing lipolytic and insulin-antagonizing properties to GH before birth. 20 The presence of GH effects on skeletal growth and fetal metabolism in the absence of documented effects on the IGFs and IGF-binding proteins may to some extent be related to the differential distribution of conventional GH receptors in fetal tissues. 21 Alternatively, these effects may be mediated by hitherto unidentified receptors that are specific for the fetus and/or placenta.…”

La sous-alimentation énergétique et/ou azotée chez la vache tarie. Effets sur les acides gras volatils du rumen, quelques métabolites et hormones du plasma et l'excrétion urinaire de la 3-méthylhistidine

“…Certains travaux menés chez les Bovins en croissance (Peters, 1986) ou en lactation (Cisse et al, 1991) et chez le mouton (Parkes et Bassett, 1985) (Brockman, 1990 (Niijima, 1989), un mécanisme mettant en jeu le réflexe vagal a également été proposé chez le mouton (Bassett, 1974b) (Trenkle, 1978 …”