Maitotoxin stimulates hormonal release and calcium flux in rat anterior pituitary cells in vitro

1984 ◽  
Vol 247 (4) ◽  
pp. E520-E525
Author(s):  
G. Schettini ◽  
K. Koike ◽  
I. S. Login ◽  
A. M. Judd ◽  
M. J. Cronin ◽  
...  
Keyword(s):  
Calcium Channels ◽  
Anterior Pituitary ◽  
Calcium Influx ◽  
Calcium Flux ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Anterior Pituitary Cells ◽  
Lh Release ◽  
Hormonal Release

The marine dinoflagellate toxin maitotoxin (MTX), an activator of calcium channels, stimulates the release of prolactin (PRL), growth hormone (GH), thyroid-stimulating hormone (TSH), and luteinizing hormone (LH) from monolayers of anterior pituitary cells in a dose-dependent manner. Maitotoxin significantly increased PRL, GH, and LH release within 1.5 min and TSH release within 3.5 min, and the stimulation continued for at least 1 h (P less than 0.01). MTX-stimulated hormonal release was blocked by the calcium channel blocker manganese (P less than 0.01). In freshly dispersed perifused pituitary cells in columns, exposure to MTX for 10 min markedly increased PRL, GH, TSH, and LH release for at least 1 h after withdrawal of the toxin. In other experiments, MTX significantly stimulated 45Ca2+ exchange by dispersed pituitary cells within 30 s, continuing for at least 30 min. We conclude that MTX increases anterior pituitary hormonal release, possibly by activating calcium channels, thereby increasing cellular calcium influx. Thus MTX may be a useful agent for investigating the involvement of Ca2+ in hormonal secretory processes.

Stimulatory effect of thyrotrophin-releasing hormone (TRH) on the release of luteinizing hormone (LH) from rat anterior pituitary cells in vitro

1983 ◽  
Vol 61 (2) ◽  
pp. 186-189 ◽  
Author(s):  
Noboru Fujihara ◽  
Masataka Shiino
Keyword(s):  
Luteinizing Hormone ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Anterior Pituitary Cells ◽  
Lh Release ◽  
Lh Rh

The effect of thyrotrophin-releasing hormone (TRH, 10−7 M) on luteinizing hormone (LH) release from rat anterior pituitary cells was examined using organ and primary cell culture. The addition of TRH to the culture medium resulted in a slightly enhanced release of LH from the cultured pituitary tissues. However, the amount of LH release stimulated by TRH was not greater than that produced by luteinizing hormone – releasing hormone (LH–RH, 10−7 M). Actinomycin D (2 × 10−5 M) and cycloheximide (10−4 M) had an inhibitory effect on the action of TRH on LH release. The inability of TRH to elicit gonadotrophin release from the anterior pituitary glands in vivo may partly be due to physiological inhibition of its action by other hypothalamic factor(s).

GRF increases release of growth hormone and arachidonate from anterior pituitary cells

1985 ◽  
Vol 248 (4) ◽  
pp. E438-E442
Author(s):  
A. M. Judd ◽  
K. Koike ◽  
R. M. MacLeod
Keyword(s):  
Growth Hormone ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Concentration Dependent Manner ◽  
Anterior Pituitary Cells ◽  
Arachidonate Release

Arachidonate and its metabolites increase growth hormone release in vitro. A study was designed to determine whether arachidonate release from anterior pituitary cells is modified by growth hormone-releasing factor (GRF) or somatostatin (SRIF). Cultured pituitary cells were incubated with [3H]arachidonate to esterify the long-chain fatty acid into cellular lipids. The cells were extensively washed with medium containing no [3H]arachidonate and then incubated with GRF and/or SRIF for 30 min. The incubation medium was then extracted with ethyl acetate, and following thin-layer chromatographic separation, the radioactivity in the [3H]arachidonate band was measured. GRF in a concentration-dependent manner (1-30 nM) stimulated growth hormone and arachidonate release, whereas SRIF (100 nM) blocked the GRF-induced increase of growth hormone and arachidonate release. The effects of GRF on growth hormone and arachidonate were evident at time intervals as brief as 5 min. These findings support the hypothesis that arachidonate may play a role in the GRF-induced growth hormone release.

Insulin, insulin-like growth factor I (IGF-I) and IGF-II enhance basal and gonadotrophin-releasing hormone-stimulated luteinizing hormone release from rat anterior pituitary cells in vitro

1994 ◽  
Vol 131 (6) ◽  
pp. 641-645 ◽  
Author(s):  
Renza Soldani ◽  
Angelo Cagnacci ◽  
Samuel SC Yen
Keyword(s):  
Growth Factor ◽  
Anterior Pituitary ◽  
Pituitary Cells ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Anterior Pituitary Cells ◽  
Igf I ◽  
Lh Release ◽  
Growth Factor I

Soldani R, Cagnacci A, Yen SSC. Insulin, insulin-like growth factor I (IGF-I) and IGF-II enhance basal and gonadotrophin-releasing hormone-stimulated luteinizing hormone release from rat anterior pituitary cells in vitro. Eur J Endocrinol 1994;131:641–5. ISSN 0804–4643 The role of insulin-like growth factor I (IGF-I) and IGF-II on luteinizing hormone (LH) release is still unclear. The present study was performed to investigate modifications of basal and gonadotrophinreleasing hormone (GnRH)-stimulated (109 mol/l) LH release, induced by a 4-h and a 24-h incubation with physiological doses of IGF-I (1, 5 and 10 nmol/l) and IGF-II (5, 10 and 15 nmol/l) in comparison with insulin (0.0017, 0.1722 and 1.722 nmol/l), from primary cultures of male rat anterior pituitary cells. Both during the 4-h and the 24-h incubation, basal and GnRH-stimulated LH release were increased by IGF-I, IGF-II and insulin in a dose-dependent fashion. Present data confirm insulin's capability of potentiating anterior pituitary LH release from dispersed rat anterior pituitary cells in vitro, and reveal similar effects for physiological doses of IGF-I and IGF-II. Renza Soldani, Instituto di Ginecologia Ostetricia e Fisiopatologia della Riproduzione Umana, Ospedale S. Giovanni di Dio, via Ospedale 46, 09124 Cagliari, Italy

Cobalt complex with GnRH stimulates the LH release and PKA signaling pathway in pig anterior pituitary cells in vitro

2005 ◽  
Vol 65 (5) ◽  
pp. 391-396 ◽  
Author(s):  
Agnieszka Blitek ◽  
Adam Ziecik ◽  
Alina Gajewska ◽  
Masato Kodaka ◽  
Raymond Counis ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Anterior Pituitary ◽  
Cobalt Complex ◽  
Pituitary Cells ◽  
Anterior Pituitary Cells ◽  
Lh Release

Tyrosine kinase inhibitors enhance GHRH-stimulated cAMP accumulation and GH release in rat anterior pituitary cells

1997 ◽  
Vol 152 (2) ◽  
pp. 193-199 ◽  
Author(s):  
T Ogiwara ◽  
C L Chik ◽  
A K Ho
Keyword(s):  
Tyrosine Kinase ◽  
Cholera Toxin ◽  
Tyrosine Kinase Inhibitors ◽  
Anterior Pituitary ◽  
Kinase Inhibitors ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Camp Accumulation ◽  
Anterior Pituitary Cells ◽  
Site Of Action

Abstract In this study, the role of tyrosine phosphorylation in agonist-stimulated cAMP accumulation and GH release in rat anterior pituitary cells was investigated. It was found that genistein, a tyrosine kinase inhibitor, while having no effect on its own, potentiated GHRH-stimulated cAMP accumulation in a concentration-dependent manner. In comparison, daidzein, an inactive analogue of genistein, was ineffective and vanadate, a phosphotyrosine phosphatase inhibitor, reduced GHRH-stimulated cAMP accumulation. Additional structurally unrelated tyrosine kinase inhibitors, erbstatin and tyrphostins, also potentiated GHRH-stimulated cAMP accumulation. To determine the site of action of the tyrosine kinase inhibitors, pituitary adenylate cyclase-activating polypeptide (PACAP), cholera toxin and forskolin were used to increase cAMP accumulation. Genistein enhanced the PACAP-, cholera toxin- or forskolin-stimulated cAMP accumulation, suggesting that the site of action is at the post-receptor level. However, when the phosphodiesterase was inhibited by isobutylmethylxanthine, genistein did not potentiate and vanadate did not inhibit GHRH-stimulated cAMP accumulation, indicating that phosphodiesterase is a probable site of action for the inhibitor. Genistein and erbstatin also enhanced GHRH-stimulated GH release and the effect of vanadate was inhibitory. These results indicate that tyrosine kinase inhibitors enhance cAMP accumulation through their action on phosphodiesterase activity in rat anterior pituitary cells and the tyrosine kinase pathway appears to be involved in the control of GH release. Journal of Endocrinology (1997) 152, 193–199

Sign in / Sign up

Export Citation Format

Share Document