Growth hormone at breeding modifies conceptus development and postnatal growth in sheep.
ABSTRACT Experiments were performed to determine the effects of components of the GH-IGF axis on conceptus development and postnatal growth in sheep. In Exp. 1, ewes received one of the following treatments: 1) sustained release GH at breeding, 2) sustained release GH at breeding and estradiol-17beta at d 5 and 6, 3) only estradiol-17beta at d 5 and 6, or 4) no treatment. Uteri were flushed on d 7, and flushings were analyzed for content of IGF-I. A single injection of sustained-release bovine GH at breeding increased IGF-I content in uterine luminal flushings compared with control ewes (P < 0.05). Treatment with estradiol-17beta on d 5 and 6 after breeding did not alter IGF-I content compared with control ewes, and it blocked the effect of GH on uterine luminal IGF-I content. In Exp. 2, sustained release GH or no treatment was administered at breeding, and gravid uteri were collected at d 25, 80, or 140 of gestation. On d 80, GH-treated ewes had smaller chorioallantoic weights (P < 0.05) and tended to have more efficient placentae (fetal weight/total placental weight; P = 0.052), with a higher percentage of placental weight as cotyledons (P = 0.068) compared with control ewes. In Exp. 3, ewes were treated with or without sustained release GH at progesterone withdrawal. Lambs from GH-treated ewes were heavier at birth (P < 0.05). Lambs from GH-treated ewes reared as singles, but not lambs reared as multiples, were heavier at 30, 60 (P < 0.05), and 75 d (P = 0.075) of age than lambs from control ewes. In conclusion, ewes treated with sustained-release GH at breeding developed smaller, more efficient placentas, and had larger lambs at birth.
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ABSTRACT: The somatotropic axis, consisting of growth hormone (GH), hepatic insulin-like growth factor I (IGF-I), and assorted releasing factors, regulates growth and body composition. Axiomatically, since optimal body composition enhances reproductive function, general somatic actions of GH modulate reproductive function. A growing body of evidence supports the hypothesis that GH also modulates reproduction directly, exerting both gonadotropin-dependent and gonadotropin-independent actions in both males and females. Moreover, recent studies indicate GH produced within reproductive tissues differs from pituitary GH in terms of secretion and action. Accordingly, GH is increasingly used as a fertility adjunct in males and females, both humans and nonhumans. This review reconsiders reproductive actions of GH in vertebrates in respect to these new conceptual developments.International Journal of Endocrinology 01/2014; 2014:234014. DOI:10.1155/2014/234014 · 1.52 Impact Factor
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ABSTRACT: Developmental programming of the fetus has consequences for physiologic responses in the offspring as an adult and, more recently, is implicated in the expression of altered phenotypes of future generations. Some phenotypes, such as fertility, bone strength, and adiposity are highly relevant to food animal production and in utero factors that impinge on those traits are vital to understand. A key systemic regulatory hormone is growth hormone (GH), which has a developmental role in virtually all tissues and organs. This review catalogs the impact of GH on tissue programming and how perturbations early in development influence GH function.02/2015; 6(1). DOI:10.1186/s40104-015-0001-8
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ABSTRACT: Objectives were to examine effects of selenium (Se) supply and maternal nutritional plane during gestation on placental size at term and maternal endocrine profiles throughout gestation and early lactation. Ewe lambs (n = 84) were allocated to treatments that included Se supply of adequate Se (ASe; 11.5 μg/kg BW) or high Se (HSe; 77 μg/kg BW) initiated at breeding and nutritional plane of 60% (RES), 100% (CON), or 140% (EXC) of requirements beginning on day 40 of gestation. At parturition, lambs were removed from their dams, and ewes were transitioned to a common diet that met requirements of lactation. Blood samples were taken from a subset of ewes (n = 42) throughout gestation, during parturition, and throughout lactation to determine hormone concentrations. Cotyledon number was reduced (P = 0.03) in RES and EXC ewes compared with CON ewes. Placental delivery time tended (P = 0.08) to be shorter in HSe ewes than in ASe ewes, whereas placental delivery time was longer (P = 0.02) in RES ewes than in CON and EXC ewes. During gestation, maternal progesterone, estradiol-17β, and GH were increased (P < 0.05) in RES ewes and decreased (P < 0.05) in EXC ewes compared with CON ewes. In contrast, maternal cortisol, IGF-I, prolactin, triiodothyronine, and thyroxine were decreased in RES ewes and increased in EXC ewes compared with CON ewes during gestation. Selenium supply did not alter maternal hormone profiles during gestation. During parturition and lactation, maternal hormone concentrations were influenced by both Se and maternal nutritional plane. During the parturient process, HSe ewes tended to have greater (P = 0.06) concentrations of estradiol-17β than ASe ewes. Three hours after parturition a surge of GH was observed in ASe-RES ewes that was muted in HSe-RES ewes and not apparent in other ewes. Growth hormone area under the curve during the parturient process was increased (P < 0.05) in ASe-RES vs HSe-RES ewes. Ewes that were overfed during gestation had reduced (P < 0.05) estradiol-17β but greater IGF-I, triiodothyronine, and thyroxine (P < 0.05) compared with RES ewes. Even though ewes were transitioned to a common diet after parturition, endocrine status continued to be affected into lactation. Moreover, it appears that gestational diet may partially affect lactational performance through altered endocrine status.Domestic Animal Endocrinology 10/2013; DOI:10.1016/j.domaniend.2013.09.006 · 1.78 Impact Factor