The effects of long term growth hormone releasing factor (GRF 1–40) administration on growth hormone secretion and synthesis in vitro

Diéguez, Carlos; Foord, Steven M.; Shewring, Gerald; Edwards, C.; Heyburn, P. J.; Peters, John R.; Hall, R.; Scanlon, M. F.

doi:10.1016/0006-291x(84)90694-6

Cited by 18 publications

(8 citation statements)

References 18 publications

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“…Dieguez et al [5] found that after a 24-hour exposure to GHRH, rat anterior pituitary cells in primary culture de monstrated an attenuated GH response to GHRH. Wehrenberg et al [16] found similar results in vivo.…”

Section: Discussionmentioning

confidence: 99%

“…Both groups noted a marked depletion of intracellular GH stores after the 24-hour period. Dieguez et al [5] concluded that deple tion of GH stores could explain the subsequent diminished response to GHRH. However, their analysis assumed that the decrease in pituitary GH content was directly propor tional to the decrease in GH secretion, an assumption that has not been adequately tested.…”

Section: Discussionmentioning

confidence: 99%

“…This phenomenon may result either from desensitization of the somatotroph, from depletion of intracellular GH pools, or from both. Previous studies have demonstrated that con tinuous GHRH infusions cause a decrease in GH stores [5,16]. Bilezikjian and Vale [2] have shown that desensitization of the GH response to GHRH and depletion of GH stores both occur in rat pituitary cells after continuous GHRH ex posure.…”

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confidence: 99%

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Effect of Continuous Somatostatin and Growth Hormone-Releasing Hormone (GHRH) Infusions on the Subsequent Growth Hormone (GH) Response to GHRH

1987

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Continuous infusions of growth hormone-releasing hormone (GHRH) attenuate the subsequent growth hormone (GH) response to GHRH. To test whether this phenomenon can occur in the absence of GH pool depletion, we examined the effects of continuous infusions of 10 nM GHRH and of 10 nM somatostatin (SRIH), separately or in combination, on dispersed, perifused rat anterior pituitary cells. Columns of these cells were given either GHRH alone for 5 h, GHRH and SRIH together for 3 h followed by GHRH alone, or SRIH alone for 3 h followed by GHRH or medium. SRIH blunted both basal GH release and the GH response to GHRH, without affecting the subsequent GH responses to GHRH. The GHRH infusions attenuated the subsequent GH response to GHRH, even when GH release was initially prevented by the concurrent infusion of SRIH. Furthermore, the degree of attenuation was similar in the presence or absence of SRIH, suggesting that pool depletion plays little role in the desensitization process under these experimental conditions. The results are consistent with the hypothesis that a short-term infusion of GHRH leads to attenuation of the GH response in rat anterior pituitary cells primarily through receptor effects rather than through GH pool depletion.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of Continuous Somatostatin and Growth Hormone-Releasing Hormone (GHRH) Infusions on the Subsequent Growth Hormone (GH) Response to GHRH

1987

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“…While Bilezikian & Vale (1984) and Ceda & Hoffman (1985) demonstrated that preincubation of cultured rat pituitary cells with G R F for 24 h resulted in significant depletion of G H and partial desensitization to subsequent G R F stimulation, Dieguez et al (1984) using a similar static incubation system, did not. The results of in-vitro studies are conflicting.…”

Section: Discussionmentioning

confidence: 98%

“…stimulated in-vitro PRL release in one of two tumours secreting both GH and PRL (Webb et al, 1983). The results of in-vitro studies with rat anterior pituitary cells are conflicting (Bilezikian & Vale, 1984;Ceda & Hoffman, 1985;Dieguez et al 1984;Spada et al 1987). These observations suggested that in some patients with acromegaly PRL is released the way GH is by GH-release-stimulating agents.…”

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confidence: 99%

GROWTH HORMONE RELEASING FACTOR STIMULATES and SOMATOSTATIN INHIBITS PROLACTIN RELEASE FROM HUMAN MIXED SOMATOTROPH‐LACTOTROPH ADENOMAS IN PERIFUSION

Serri

1987

Clinical Endocrinology

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The effects of human growth hormone-releasing factor (hGRF) and somatostatin on growth hormone (GH) and prolactin (PRL) secretion in perifusion of dispersed cells of human GH-secreting adenomas, obtained from seven acromegalic patients with hyperprolactinaemia, were examined. Six adenomas stained for both GH and PRL on immunohistochemical examination, and one contained only GH. GH release was consistently stimulated in a dose-dependent manner by hGRF (0.01, 0.1 and 1.0 nM) in all seven adenomas studied. PRL release was undetectable in two adenomas. In the other five, hGRF stimulated PRL release and the response was dose related. Furthermore, the PRL response was significantly correlated with the GH response to hGRF. When cells were perfused with somatostatin (1 nM), GH and PRL secretion induced by hGRF was completely antagonized. We also evaluated the effect of hGRF pretreatment on the subsequent GH response to hGRF in two adenomas. hGRF pretreatment (1 nM) for 210 min reduced the GH response to a subsequent hGRF challenge (100 nM) in one tumour but not in the other. In conclusion, the PRL response is similar to the GH response in mixed GH and PRL-secreting adenomas after exposure to GH release-stimulating and inhibiting hormones. After prolonged exposure to hGRF, some adenomas remain responsive to further stimulation with hGRF, whereas others do not.

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Administration of human pancreatic growth hormone-releasing factor (GRF) analogs enhances responsiveness of cultured rat pituitary cells to GRF

Heiman

Murphy

Nekola

et al. 1984

Biochemical and Biophysical Research Communications

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The effects of long term growth hormone releasing factor (GRF 1–40) administration on growth hormone secretion and synthesis in vitro

Cited by 18 publications

References 18 publications

Effect of Continuous Somatostatin and Growth Hormone-Releasing Hormone (GHRH) Infusions on the Subsequent Growth Hormone (GH) Response to GHRH

Effect of Continuous Somatostatin and Growth Hormone-Releasing Hormone (GHRH) Infusions on the Subsequent Growth Hormone (GH) Response to GHRH

GROWTH HORMONE RELEASING FACTOR STIMULATES and SOMATOSTATIN INHIBITS PROLACTIN RELEASE FROM HUMAN MIXED SOMATOTROPH‐LACTOTROPH ADENOMAS IN PERIFUSION

Administration of human pancreatic growth hormone-releasing factor (GRF) analogs enhances responsiveness of cultured rat pituitary cells to GRF

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