Uneven Regional Distributions of Prolactin- and Growth Hormone-Secreting Cells and Sexually Dimorphic Proportions of Prolactin Secretors in the Adenohypophysis of Adult Chickens

Lopez, Marisol E.; Hargis, Billy M.; Dean, Cleon E.; Porter, Tom E.

doi:10.1006/gcen.1995.1154

Cited by 29 publications

(20 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Finally, PRL-or GH-positive cells were developed by incubating with substrate (VIP kit, Vector Laboratories). The GH and PRL antisera used have been described and validated previously (Lopez et al 1995. Data shown are the percentage of PRL-or GH-containing cells among at least 300 cells counted per well.…”

Section: Immunocytochemistry (Icc)mentioning

confidence: 99%

Evidence that lactotrophs do not differentiate directly from somatotrophs during chick embryonic development

Nishimura²,

Porter

2004

Journal of Endocrinology

View full text Add to dashboard Cite

It is generally accepted that, in mammals, lactotrophs differentiate from somatotrophs through an intermediate cell type, the mammosomatotroph. However, little information exists about mammosomatotrophs and their relationship with lactotroph development in non-mammalian vertebrates. We reported previously that corticosterone (CORT) can induce both somatotroph and lactotroph differentiation in cultures of chicken embryonic pituitary cells. Our current objectives were to determine the abundance of mammosomatotrophs during chicken pituitary development, to identify mammosomatotrophs during CORT induction of lactotrophs, and to explore whether lactotrophs induced by CORT are derived from somatotrophs. Cells that produced prolactin (PRL) only, growth hormone (GH) only or both hormones simultaneously were detected by three approaches -dual immunofluorescence, a combination of immunofluorescence and immunocytochemistry (ICC), and by ICC using combinations of antibodies to GH and PRL. Mammosomatotrophs were not detected between embryonic day (E) 16 and E20, even though lactotrophs increased from nearly absent to greater than 10% of all pituitary cells during this period. CORT induced more than 10% of all E13 pituitary cells to produce PRL, while the percentage of mammosomatotrophs remained at less than 1% of all cells. When cells from the cephalic and caudal lobes of the anterior pituitary were treated separately, CORT increased GH cells in cultures from the caudal lobe. No PRL cells were found in the caudal lobe. In the cephalic lobe, CORT increased lactotrophs, while GH cells were barely detected. In summary, mammosomatotrophs are rare during chicken pituitary development, and CORT does not induce lactotrophs from somatotrophs. These findings indicate that, unlike in mammals, lactotrophs do not differentiate from somatotrophs during chicken embryonic development.

show abstract

Section: Immunocytochemistry (Icc)mentioning

confidence: 99%

Evidence that lactotrophs do not differentiate directly from somatotrophs during chick embryonic development

Nishimura²,

Porter

2004

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…While many GH-containing cells were induced in cultures derived from the cephalic lobe, nearly half of all cells obtained from the caudal lobe produced GH in response to corticosterone. The caudal lobe of the anterior pituitary is the same region where somatotrophs are located in adults (Lopez et al 1995) and where GH mRNA is expressed prematurely in response to corticosterone administration in vivo (Bossis & Porter 2000). Together, these findings indicate that the corticosterone-induced population of GH cells likely reflects those cells that were destined to differentiate into somatotrophs at a later age and that the induced somatotrophs are fully functional in their responses to GHRH and TRH.…”

Section: Discussionmentioning

confidence: 78%

“…These cells were then recovered and subjected to GH RHPAs. To determine whether corticosterone-induced somatotrophs originated in the caudal lobe of the chick anterior pituitary, the microanatomical location of somatotrophs in adult chickens (Lopez et al 1995), the caudal half and cephalic half of e12 pituitary glands were dissociated separately along with entire anterior pituitary glands from other embryos, and the resulting cells from the caudal lobe, the cephalic lobe and the entire anterior pituitary gland were treated for 24 h with 10 9 M corticosterone. GHcontaining cells were identified by immunocytochemistry as described below.…”

Section: Animals and Cell Culturementioning

confidence: 99%

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

Porter

Dean²,

Piper³

et al. 2001

Journal of Endocrinology

View full text Add to dashboard Cite

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.

show abstract

“…Prolactin-containing cells are distributed throughout the gland [29,30], although two groups of cells were distinguished, one centrally located and one forming a narrow peripheral rim on the gland [31]. In mice, lactotrophs are generally distributed except in the cephalic ventromedial area [28] and in chickens are localized in the cephalic lobe [32]. Lactotrophs exist in close proximity to gonadotrophs in some regions of the gland of rats and also horses [33][34][35].…”

mentioning

confidence: 99%

“…Lactotrophs exist in close proximity to gonadotrophs in some regions of the gland of rats and also horses [33][34][35]. Somatotrophs in rats are evenly distributed sagitally and rostrocaudally, but unevenly dorsoventrally [36]; in mice, somatotrophs are generally distributed except in the cephalic ventromedial area [28]; in chickens GH-secreting cells are localized in the caudal lobe [32]. Corticotrophs have mainly an even distribution, frequently in juxtaposition to somatotrophs [26] and are less frequently observed in the antero-ventral region and the area immediately adjacent to the intermediate lobe.…”

mentioning

confidence: 99%

Editorial: The Anterior Pituitary Gland - Co-Ordinating an Alphabet of Peptides

Evans¹

2011

TONEUROEJ

View full text Add to dashboard Cite

The pituitary has been described as the Master Gland, even as we progress through the contemporary era of comprehensive proteomic arrays [1,2]. The label is a reflection of the range of the gland's influences. The variety of contributions that the anterior pituitary gland makes to so many of the clearly observable events as well as covert metabolic processes in the body (e.g. stress, reproduction, growth) is a result of many pathways within the multi-cell tissue. The anterior pituitary is covered by a fibrous capsule, and the parenchyma is composed substantially of epithelial secretory cells arranged in cords or follicles. A network of fenestrated capillaries provides a system that enables transport of secretions to other distant tissues. The gland was until recent times summarised as having five endocrine cell types [3], which were later called corticotrophs, gonadotrophs, lactotrophs, somatotrophs and thyrotrophs, and additionally some apparently non-endocrine cells were identified, including folliculo-stellate cells. This model of the pituitary was a useful staging post for the investigative process. Biology is well fertilised with temporary hypotheses that enable questions to be formulated and prevailing views examined. There is sometimes danger that a plausible guess becomes sanctified as dogma. One can wonder if for a short time such occurred with this tidy model of the adenophypohysis, and in the mid 20th century some evidence for paracrine interactions were ignored by some researchers.Nevertheless these ideas aroused considerable excitement, and were supported by much more detailed evidence than the earlier suggestions, proposed by Galen in the second century AD, that the pituitary was a receptacle for mucus that had drained from the brain through the pituitary stalk and filtered to the nasopharynx. In fact the speculatively inaccurate interpretation led to the gland being named from the Latin word for mucus, 'pituita', and the adjective 'pituitous' meaning mucoid was derived.The adenohypophysis is a network of cells, which must co-ordinate their secretions so that the pituitary is able to respond with appropriate activity in particular circumstances. Further, pituitary cells are themselves dependent for their own differentiation and growth on a large group of compounds which are derived from the pituitary, such as nitric oxide, endothelin, and insulin-like growth factor. The hormones traditionally associated with the anterior pituitary gland were characterised, and the regulation for their secretion was proposed, by Geoffrey Harris, as being dependent on the capillaries connecting it to the hypothalamus. Then the releasing factors were discovered. In 1977 Roger Guilleman and Andrew Schally were awarded the Nobel Prize for their discoveries concerning the peptide hormone production of the brain. Interactions between these hypothalamic factors and intrapituitary compounds is an important component in regulating pituitary endocrine function (e.g. the GnRH-activin-follistatin module reviewed here [4]).It wa...

show abstract

Uneven Regional Distributions of Prolactin- and Growth Hormone-Secreting Cells and Sexually Dimorphic Proportions of Prolactin Secretors in the Adenohypophysis of Adult Chickens

Cited by 29 publications

References 0 publications

Evidence that lactotrophs do not differentiate directly from somatotrophs during chick embryonic development

Evidence that lactotrophs do not differentiate directly from somatotrophs during chick embryonic development

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

Editorial: The Anterior Pituitary Gland - Co-Ordinating an Alphabet of Peptides

Contact Info

Product

Resources

About