Influence of Coexisting Hypothalamic Messengers on Growth Hormone Secretion from Rat Anterior Pituitary Cells in vitro

1987 ◽  
Vol 46 (5) ◽  
pp. 387-394 ◽  
Author(s):  
Björn Meister ◽  
Anna-Lena Hulting
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells

On the role of the peptide galanin in regulation of growth hormone secretion

1991 ◽  
Vol 125 (5) ◽  
pp. 518-525 ◽  
Author(s):  
Anna-Lena Hulting ◽  
Björn Meister ◽  
Lena Carlsson ◽  
Agneta Hilding ◽  
Olle Isaksson
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Human Anterior Pituitary ◽  
Plasma Gh

Abstract. The effects of the peptide galanin on growth hormone secretion were studied in vitro using cultured rat and human anterior pituitary cells, and in vivo by iv administration of galanin in both rats and humans. Galanin in concentrations from 10 nmol/l to 1 μmol/l did not alter basal GH release, but slightly inhibited GHRH-stimulated GH release from cultured rat anterior pituitary cells. Galanin (1 μmol/l) did not significantly change basal or GHRH-stimulated GH secretion from cultured human anterior pituitary cells. In contrast, iv injection of 1 μg (300 pmol) galanin to rats induced an increase in plasma GH that was reproducible at repetitive injections. The galanin-induced GH release in rats was of a lower magnitude than the increase in plasma GH after iv injections of GHRH, and was seen with a 5-15 min delay in comparison to iv administered GHRH. In man, iv infusions of galanin (40 pmol ·kg−1 · min−1 · (40 min)) also caused a significant increase in plasma GH, but it occurred 25-30 min after the beginning of the infusion. These results suggest an indirect action of galanin on GH release in both rats and humans, i.e. galanin does not directly affect the somatotropes. In agreement with a central action, no binding sites for galanin could be demonstrated in the rat anterior pituitary by autoradiography. Since galanin did not affect somatostatin release from fragments of rat mediobasal hypothalamus, the stimulatory effects of galanin on GH release are most likely mediated via a stimulatory effect on GHRH neurons.

GRF elevates cytosolic free calcium concentration in rat anterior pituitary cells

1987 ◽  
Vol 253 (5) ◽  
pp. E591-E594
Author(s):  
C. Schofl ◽  
J. Sandow ◽  
W. Knepel
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Calcium Concentration ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Free Calcium ◽  
Pituitary Cells ◽  
Maximal Increase ◽  
Anterior Pituitary Cells ◽  
Free Calcium Concentration

The effect of human growth hormone-releasing factor (GRF) on intracellular free calcium concentration ([Ca2+]i) was examined in rat anterior pituitary cells. The [Ca2+]i was monitored directly by means of the intracellularly trapped fluorescent indicator, fura-2. GRF rapidly elevated [Ca2+]i, reaching a new plateau within approximately 30 s. The half-maximally effective concentration of GRF was approximately 130 pM. GRF produced a maximal increase in [Ca2+]i by approximately 120 nM. The GRF (2 nM)-induced elevation of [Ca2+]i was abolished by removal of extracellular calcium (Ca2+ omitted, 2 mM EGTA). The GRF (2 nM)-caused rise in [Ca2+]i was largely reduced in the presence of the calcium channel blockers Mg2+ (31.2 mM) or nifedipine (1 microM). An increase in [Ca2+]i by approximately 60 nM was elicited by the addition of prostaglandin E2 (1 microM), which can stimulate growth hormone secretion independent of GRF receptors. These data indicate that GRF elevates the [Ca2+]i, possibly in somatotrophs; this GRF-induced increase in [Ca2+]i may depend on an influx of extracellular Ca2+, largely through Mg2+- and nifedipine-sensitive calcium channels.

Regulational Effect of Ghrelin on Growth Hormone Secretion from Perifused Rat Anterior Pituitary Cells

2002 ◽  
Vol 14 (2) ◽  
pp. 156-162 ◽  
Author(s):  
M. Yamazaki ◽  
K. Nakamura ◽  
H. Kobayashi ◽  
M. Matsubara ◽  
Y. Hayashi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells

Growth hormone-releasing factor-induced growth hormone secretion from perifused rat anterior pituitary cells: lack of influence of glucose concentration, and normal responses in pituitary cells from diabetic animals

1989 ◽  
Vol 122 (3) ◽  
pp. 657-660 ◽  
Author(s):  
G. Caldwell ◽  
G. Hart ◽  
E. M. Kohner ◽  
J. M. Burrin
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Initial Response ◽  
Diabetic Rats ◽  
Pituitary Cells ◽  
Gh Secretion ◽  
Anterior Pituitary Cells ◽  
Streptozotocin Induced Diabetes

ABSTRACT The mechanism responsible for the suppression of GH secretion in hyperglycaemia and hypoglyceamia in rats has been investigated using perifusion of anterior pituitary cells. When perifused with Krebs-Ringer bicarbonate containing normal (5 mmol/l), high (20 mmol/l) and low (1 mmol/l) concentrations of glucose, the GH responses to GH-releasing factor (GRF) were 85 ± 5, 85·5 ± 5·4 and 89 ± 3·0 (s.e.m.)% respectively compared with the initial response to GRF at 5 mmol/l in each column. The mean GH response to GRF from anterior pituitary cells of normal rats was 6·58 ± 0·88 μg/three pituitaries, which was not statistically different from that of cells from rats with streptozotocin-induced diabetes (5·40 ± 0·68 μg/three pituitaries). It is concluded that GH suppression in diabetic rats and during hypoglycaemia is not mediated by changes in the GH response to GRF. Journal of Endocrinology (1989) 122, 657–660

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