Endocrine effects of degradation-stabilized thyrotropin-releasing hormone (TRH) analogues on primary rat pituitary cell cultures

1988 ◽  
Vol 117 (4_Suppl) ◽  
pp. S94-S95
Author(s):  
V. KIRSCHNER ◽  
L. KIESEL ◽  
T. RABE ◽  
B. RUNNEBAUM
Keyword(s):  
Cell Cultures ◽  
Pituitary Cell ◽  
Thyrotropin Releasing Hormone ◽  
Endocrine Effects ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Trh Analogues

Role of guanine nucleotide-binding proteins, Giα3 and Gsα, in dopamine and thyrotropin-releasing hormone signal transduction: evidence for competition and commonality

1996 ◽  
Vol 148 (3) ◽  
pp. 447-455 ◽  
Author(s):  
R D Kineman ◽  
T W Gettys ◽  
L S Frawley
Keyword(s):  
Signal Transduction ◽  
G Proteins ◽  
Cell Cultures ◽  
Intracellular Signaling ◽  
Receptor Activation ◽  
Pituitary Cell ◽  
Thyrotropin Releasing Hormone ◽  
Female Rats ◽  
Releasing Hormone

Abstract It is clear that dopamine (DA) at high concentrations (>100 nmol/l) inhibits the release of prolactin (PRL). Paradoxically, this monoamine at low concentrations (<10 nmol/l) has also been shown to augment PRL secretion. One possible explanation for these divergent effects is that DA binds receptors capable of interacting with multiple G protein subtypes that recruit opposing intracellular signaling pathways within lactotropes. To identify G proteins which couple DA receptor activation to PRL secretion, we have selectively immunoneutralized the activity of Giα3 and Gsα in primary cultures of rat pituitaries and subsequently tested the ability of these cultures to respond to high and low dose DA. Specifically, permeabilized pituitary cell cultures from random-cycling female rats were treated with control immunoglobulins (IgGs; 50 μg/ml) purified from preimmune serum (PII) or IgGs directed against the C-terminal portion of Giα3 or Gsα. After immunoneutralization of these G proteins, cells were challenged with 10 or 1000 nmol Da/l and the relative amount of PRL released was assessed by reverse hemolytic plaque assay. Results were expressed as % of basal values and compared. Under control conditions (PII), 1000 nmol DA/l inhibited (61·4 ±7·6% of basal values; mean ± s.e.m.) while 10 nmol DA/l augmented (120·0 ± 7·0%) PRL release in five separate experiments. Treatment of cells with anti-Giα3 attenuated the inhibitory effect of high dose DA (87·3 ± 14·5%). However, elimination of Giα3 activity did not significantly alter the PRL stimulatory effect of 10 nmol DA/l (121·0 ± 5·2%). Interestingly, immunoneutralization of Gsα resulted in a reciprocal shift in the activity of the lower dose of DA from stimulatory to inhibitory (69·7 ± 7·3%) while combined treatment of anti-Giα3 and anti-Gsα abrogated the responsiveness of pituitary cell cultures to either DA treatment (1000 nmol/l, 70·7 ± 12·5% and 10 nmol/l, 87·5 ± 21·4%). These data reveal that ligand-activated DA receptors can interact with both Giα3 and Gsα. Elimination of the stimulatory component (Gsα) favors the DA receptor activation of the inhibitory pathway (Giα3) suggesting a competition between negative and positive intracellular signaling mechanisms in normal lactotropes. In addition to DA treatment, we also challenged permeabilized pituitary cells with 100 nmol thyrotropin-releasing hormone (TRH)/1 as a positive control for secretory integrity. As anticipated, TRH stimulated PRL release to 188·0±31·0% of basal values under control conditions. Unexpectedly, immunoneutralization of Gsα completely blocked the ability of TRH to induce PRL release (101·8 ± 12·0% This neutralizing effect was specific to Gsα in that blockade of Giα3 activity had no significant effect on TRH-stimulated PRL release (166·2 ± 13·1%). These data are the first to support a direct role of Gsα in TRH signal transduction within PRL-secreting cells. Journal of Endocrinology (1996) 148, 447–455

Regulation of the Synthetic Rate of Gonadotropin- Releasing Hormone Receptors in Rat Pituitary Cell Cultures by Inhibin*

Endocrinology ◽  
1990 ◽  
Vol 127 (5) ◽  
pp. 2387-2392 ◽  
Author(s):  
TIM D. BRADEN ◽  
PAUL G. FARNWORTH ◽  
HENRY G. BURGER ◽  
P. MICHAEL CONN
Keyword(s):  
Cell Cultures ◽  
Hormone Receptors ◽  
Gonadotropin Releasing Hormone ◽  
Pituitary Cell ◽  
Releasing Hormone ◽  
Synthetic Rate ◽  
Rat Pituitary

EFFECT OF THYROID HORMONES ON GONADOTROPHIN RELEASE AND BIOSYNTHESIS USING RAT PITUITARY CELL CULTURES

1980 ◽  
Vol 85 (2) ◽  
pp. 229-235 ◽  
Author(s):  
ASHOK KHAR ◽  
T. TAVERNY-BENNARDO ◽  
MARIAN JUTISZ
Keyword(s):  
Amino Acids ◽  
Thyroid Hormones ◽  
Cell Cultures ◽  
Actinomycin D ◽  
Pituitary Cell ◽  
Total Proteins ◽  
Releasing Hormone ◽  
Rat Pituitary ◽  
Gonadotrophin Releasing Hormone

The effect of thyroid hormones, tri-iodothyronine (T3) and thyroxine (T4) on the gonadotrophin releasing hormone (GnRH)-induced release of LH and FSH has been studied using dispersed rat pituitary cell cultures. Both T3 and T4 significantly inhibited the release of gonadotrophins in the presence of GnRH. Actinomycin D and cycloheximide also inhibited synergistically the release of LH and FSH. The incorporation of labelled amino acids and glucosamine into LH and FSH which was stimulated by GnRH was also inhibited by T3 and T4. Gonadotrophin releasing hormone had no effect on the incorporation of labelled amino acids and glucosamine into total proteins but this incorporation was also significantly inhibited by T3 and T4, the former being the more potent.

scholarly journals Synthesis and characterization of a high-affinity photoactivatable analogue of thyrotropin-releasing hormone

1992 ◽  
Vol 281 (1) ◽  
pp. 179-184
Author(s):  
K D Brady ◽  
A H Tashjian
Keyword(s):  
Thyrotropin Releasing Hormone ◽  
British Library ◽  
Releasing Hormone ◽  
High Affinity ◽  
Sds Page ◽  
Rat Pituitary ◽  
Single Polypeptide ◽  
Trh Analogues ◽  
Trh Receptor

An analogue of thyrotropin-releasing hormone (TRH, pGlu-His-ProNH2), i.e. pGlu-His-ProNH-(CH2)6-(4-azidosalicylamide) (TRH-ASA), has been synthesized and, in a radioiodinated form (TRH-IASA), characterized and used as a photoaffinity reagent to label the TRH receptor on rat pituitary GH4C1 cells. TRH-IASA bound to GH4C1 cells with high affinity (Kd = 8 nM), comparable with that of TRH binding. The binding of TRH-IASA was competitive with binding of TRH, two TRH analogues and a TRH receptor antagonist, chlordiazepoxide. TRH-IASA did not bind to or label GH12C1 cells, which lack functional TRH receptors. Labelling of GH4C1 cells with TRH-IASA followed by SDS/PAGE and autoradiography of membrane proteins demonstrated labelling of a single polypeptide which ran as a diffuse band between 71 and 91 kDa, centred at 76 kDa. No change in this labelling pattern was observed as a function of the length of time (between 5 min and 2 h) that GH4C1 cells were incubated with 3 nM-TRH-IASA. Using either a very short (5 s) photolysis interval or low TRH-IASA concentrations, only the 76 kDa band was labelled. Minor bands appeared only after extended photolysis and use of high TRH-IASA concentrations. We conclude that the TRH receptor from rat pituitary GH4C1 cells is a single peptide with an apparent molecular mass of 76 kDa. Details of the chemical synthesis of TRH-ASA are given in Supplementary Publication SUP 50167 (5 pages), which has been deposited at the British Library Document Supply Centre, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1992) 281, 5.

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