Endocrine Regulation of the Growth/Development of Warm-Blooded Vertebrate Embryos/Fetuses

Thommes, Robert C.; Woods, Jennifer

doi:10.1016/b978-0-12-629055-4.50024-6

Cited by 7 publications

(2 citation statements)

References 195 publications

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“…The late ontogeny of pituitary somatotrophs and pituitary GH secretion during incubation and gestation (Hill 1992, Thommes & Woods 1993, Porter 1997) and the inability of exogenous GH to promote embryonic or fetal growth (Hill 1992, Thommes et al 1992), supports this view. It is, therefore, thought that early embryonic or fetal growth is regulated by local growth factors rather than by endocrine secretions (Geffner 1996).…”

Section: Introductionsupporting

confidence: 48%

Extra-pituitary growth hormone in peripheral tissues of early chick embryos

Harvey

Johnson²,

Sanders³

2000

Journal of Endocrinology

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Early embryonic growth is independent of pituitary growth hormone (GH), since it occurs prior to the differentiation of pituitary somatotrophs. Embryogenesis is therefore thought to be regulated by local growth factors. As GH is now known to be produced in many extrapituitary sites, in which it acts in an autocrine or paracrine manner, the possibility that extra-pituitary GH may participate in embryogenesis and organogenesis was assessed by determining the immunocytochemical presence and location of GH-and GH-receptor (GHR)-like proteins in the peripheral tissues of chick embryos during their 21-day incubation period.Immunoreactive (IR)-GH, detectable by a monoclonal and two polyclonal antibodies for chicken GH, was specifically and ubiquitously present in tissues of 3-day-old embryos. At embryonic day (ED) 5, IR-GH was widespread in ectodermal, mesodermal and endodermal tissues, but it was not present in every cell of each tissue. IR-GH was particularly abundant in the neural tube, notochord, limb bud, somites, heart, stomach, liver, kidney, Wolffian duct and the amnion. By ED8, IR-GH was still widespread and was now present in limb bud cartilage, although the heart and liver were no longer GH immunoreactive. GH receptor immunoreactivity was also present in most tissues and cells of ED3-ED8 embryos.These results demonstrate that extrapituitary GH is abundantly present during early embryogenesis, prior to the differentiation of pituitary somatotrophs (at ED12). Since GH-and GHR-like proteins are present in most tissues of the chick embryo, it is proposed that extrapituitary GH may act as a local growth factor during embryonic development.

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Section: Introductionsupporting

confidence: 48%

Extra-pituitary growth hormone in peripheral tissues of early chick embryos

Harvey

Johnson²,

Sanders³

2000

Journal of Endocrinology

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“…Thyroid hormones are known to play an important role in the regulation of growth in mammals [reviewed by Thommes and Woods (1993)]. Thyroid hormone metabolism is significantly altered by increased circulating levels of glucocorticoids in animals and humans (Wartofsky and Burman 1982;Cavalieri 1986;Ferguson 1988).…”

mentioning

confidence: 99%

Dexamethasone ester treatment alters insulin-like growth factor-I, its binding proteins and thyroid status in finishing calves

Bertozzi¹,

Portetelle²,

Massart³

et al. 2000

Can. J. Anim. Sci.

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Dexamethasone ester treatment alters insulin-like growth factor-I, its binding proteins and thyroid status in finishing calves. Can. J. Anim. Sci. 80: 329-335. To improve carcass quality in finishing calves, some breeders use preparations containing corticoids alone or in association with other growth promoters. We have investigated the effects of dexamethasone treatment on insulin-like growth factor-I (IGF-I), IGF-binding proteins (IGFBP-2 and -3) and thyroid hormones (T 3 , T 4 , free T 4 ). Limousine male calves were allocated to a control group (C) (n = 18) and a group (n = 18) that received dexamethasone esters (DEX). Blood and hepatic tissue samples were collected at slaughtering. Thyroid hormones and IGF-I plasma levels were measured by RIA and IGFBPs were evaluated by immunoblotting. Hepatic type I 5′deiodinase (5′D-I) activity was determined by enzyme assay and hepatic expression of mRNA for GH receptor, IGF-I, IGFBP-2, IGFBP-3 and type I deiodinase (D-I) was evaluated by dot blot analysis. Plasma IGF-I and IGFBP-3 levels were reduced by the DEX treatment (P < 0.001 and P < 0.01, respectively) while IGFBP-2 was unaffected. Significant plasma changes for IGF-I and IGFBP-3 were not corroborated by hepatic mRNA levels, for which only a slight non-significant decrease was noted. Growth hormone receptor mRNA expression was increased after treatment (P < 0.01). T 3 plasma level was higher in DEX animals (P < 0.05) than in C calves. Finally, treatment increased 5′D-I activity in the hepatic tissue (P < 0.001) and seemed to also affect D-I mRNA expression (P = 0.1). In conclusion, dexamethasone ester injection in calves altered some of their endocrinological parameters; this could explain the catabolic action of corticoids in the bovine species.

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