Evidence that somatotroph differentiation during chicken embryonic development is stimulated by a blood-borne signal.

Porter, Tom E.; Couger, Gregory S.; Morpurgo, Benjamin

doi:10.1210/endo.136.9.7649077

Cited by 39 publications

(26 citation statements)

References 27 publications

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“…9). Moreover, since pituitary somatotrophs do not secrete GH until ED16 (Porter 1997) and as GH is not detectable in plasma until ED17 (Harvey et al 1979), this GH immunoreactivity in embryonic tissues cannot result from the sequestration of pituitary GH from peripheral plasma.…”

Section: Discussionmentioning

confidence: 99%

“…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: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Harvey

Johnson²,

Sanders³

2000

Journal of Endocrinology

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“…However, it seems unlikely that each of these sensitive techniques was unable to detect this population of somatotrophs. Furthermore, in our previous reports (Porter et al 1995b, Morpurgo et al 1997) treatment with GHRH or TRH, the principal stimulatory GH secretagogues in chickens, for 2 to 6 days failed to increase the abundance of GH-secreting cells in cultures of embryonic pituitary cells. Similarly, the aqueous phase of ether-extracted embryonic serum failed to induce GH cell differentiation (Morpurgo et al 1997).…”

Section: Discussionmentioning

confidence: 82%

“…Previous work by our group established that, in contrast to corticosterone, treatment of e12 chicken pituitary cells with GHRH for as many as 6 days failed to increase the percentage of GH-secreting cells (Porter et al 1995b. This finding was surprising, because GHRH has been shown to stimulate proliferation of rat somatotrophs in vitro (Billestrup et al 1986).…”

Section: Discussionmentioning

confidence: 89%

“…Somatotrophs first appear in the developing chick by embryonic day (e) 14 and become a significant population by e16 (Jozsa et al 1979, Barabanov 1991, Porter et al 1995a. This ontogenic profile correlates with the capacity of serum from chick embryos to induce GH cell differentiation in vitro (Porter et al 1995b), wherein serum from e16 but not e12 can induce the appearance of GH-secreting cells in culture. The GH cell-differentiating activity of e16 chicken serum was attributed to endogenous levels of the adrenal glucocorticoid corticosterone (Morpurgo et al 1997).…”

Section: Introductionmentioning

confidence: 99%

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Somatotroph recruitment by glucocorticoids involves induction of growth hormone gene expression and secretagogue responsiveness

Porter

Dean²,

Piper³

et al. 2001

Journal of Endocrinology

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Prior research indicates that growth hormone (GH) cell differentiation can be induced prematurely by treatment with glucocorticoids in vitro and in vivo. However, the nature of these responses has not been fully characterized. In this study, the time course of corticosterone induction of GH-secreting cells in cultures of chicken embryonic pituitary cells, responsiveness of differentiated somatotrophs to GH secretagogues, localization of somatotroph precursor cells within the pituitary gland, and the effect of corticosterone on GH gene expression were determined to better define the involvement of glucocorticoids in somatotroph recruitment during development. Anterior pituitary cells from embryonic day 12 chicken embryos were cultured in 10 9 M corticosterone for 4 to 48 h and were then subjected to reverse haemolytic plaque assays (RHPAs) for GH. Corticosterone treatment for as short as 16 h increased the percentage of GH cells compared with the control. When corticosterone was removed after 48 h and cells were cultured for an additional 3 days in medium alone, the percentage of GH secretors decreased but remained greater than the proportion of somatotrophs among cells that were never treated with corticosterone. To determine if prematurely differentiated somatotrophs were responsive to GH secretagogues, cells were exposed to corticosterone for 48 h and then subjected to GH RHPAs in the presence or absence of GH-releasing hormone (GHRH) or thyrotropin-releasing hormone (TRH). Approximately half of the somatotrophs induced to differentiate with corticosterone subsequently released more GH in response to GHRH and TRH than in their absence. The somatotroph precursor cells were localized within the anterior pituitary by culturing cells from the caudal lobe and cephalic lobe of the anterior pituitary separately. Corticosterone induction of GH cells was substantially greater in cultures derived from the caudal lobe of the anterior pituitary, where somatotroph differentiation normally occurs. GH gene expression was evaluated by ribonuclease protection assay and by in situ hybridization. Corticosterone increased GH mRNA in cultured cells by greater than fourfold. Moreover, corticosterone-induced somatotroph differentiation involved GH gene expression in cells not expressing GH mRNA previously, and the extent of somatotroph differentiation was augmented by treatment with GHRH in combination with corticosterone. We conclude that corticosterone increases the number of GH-secreting cells within 16 h, increases GH gene expression in cells formerly not expressing this gene, confers somatotroph sensitivity to GHRH and TRH, and induces GH production in a precursor population found primarily in the caudal lobe of the anterior pituitary, a site consistent with GH localization in adults. These findings support the hypothesis that glucocorticoids function to induce the final stages in the differentiation of fully functional somatotrophs from cells previously committed to this lineage.

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Prospects ofin ovofeeding and nutrient supplementation for poultry: the science and commercial applications—a review

et al. 2013

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In ovo supplementation of poultry embryos was first reported several decades ago, but it is only recently that concerted research has been directed at developing the technology for this process to be routinely used by the poultry industry. Although the technology of in ovo feeding was patented more than 10 years ago, it has not been widely adopted by the poultry industry. This review examines the early development of the enteric system of the poultry embryo; defines and distinguishes between in ovo feeding and in ovo nutrient administration; highlights the importance of early feeding of the chick; and discusses the development of in ovo feeding technology and its effects on hatchability, growth, gut health and immune response of chicks. The range of possible nutrients that can be administered is also explored. The limitations associated with embryo development and nutrient metabolism are highlighted, leading to the prediction of the future role of in ovo feeding in the poultry industry.

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Evidence that somatotroph differentiation during chicken embryonic development is stimulated by a blood-borne signal.

Cited by 39 publications

References 27 publications

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

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

Somatotroph recruitment by glucocorticoids involves induction of growth hormone gene expression and secretagogue responsiveness

Prospects ofin ovofeeding and nutrient supplementation for poultry: the science and commercial applications—a review

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