Skip to main content
SpringerLink
Log in

Different G proteins are involved in the biphasic response of clonal rat pituitary cells to thyrotropin-releasing hormone

  • Published:
Pflügers Archiv Aims and scope Submit manuscript

Abstract

In rat anterior pituitary tumour cells (GH3/B6) thyrotropin-releasing hormone (TRH) elicits a biphasic response. First, a release of intracellularly stored Ca2+ induces a hyperpolarization of the cell. Second, a depolarization thought to be induced by a reduction of the inward-rectifying K+ current (KIR) causes an increase in action potential frequency and a plateau-like increase in [Ca2+]i. It has been proposed that the two phases are induced by the actions of inositol 1,4,5-trisphosphate (InsP 3) and protein kinase C (PKC), respectively, but we demonstrate here that PKC is not responsible for the second phase increase in [Ca2+]i and suggest that the pathways diverge at the level of receptor and G protein coupling. Both phases of the TRH response were insensitive to pertussis toxin, but cholera toxin (CTX) selectively affected the second phase. After CTX pretreatment cells had a high spontaneous spiking frequency and smaller KIR amplitude. In these cells TRH failed to increase the action potential frequency after the first phase hyperpolarization, elicited only a transient peak increase in [Ca2+]i with no plateau phase and could only slightly reduce KIR. These effects of CTX are not mediated by its ability to increase cAMP via activation of GS, as increased cAMP levels neither inhibit KIR nor prevent its reduction by TRH. In addition, inhibition of protein kinase A activation did not block the second phase increase in [Ca2+]i induced by TRH, suggesting that the CTX-sensitive G protein mediating the second phase of the TRH response is not GS.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  1. Aragay AM, Katz A, Simon MI (1992) The Gα q and Gα11 proteins couple the thyrotropin-releasing hormone receptor to phospholipase C in GH3 rat pituitary cells. J Biol Chem 267:24 983–24 988

    Google Scholar 

  2. Barros F, Delgado LM, del Camino D, de la Peña P (1992) Characteristics and modulation by thyrotropin-releasing hormone of an inwardly-rectifying K+ current in patch-perforated GH3 anterior pituitary cells. Pflügers Arch 422:31–39

    Google Scholar 

  3. Bauer CK, Meyerhof W, Schwarz JR (1990) An inward-rectifying K+ current in clonal rat pituitary cells and its modulation by thyrotrophin-releasing hormone. J Physiol (Lond) 429:169–189

    Google Scholar 

  4. Brunet N, Gourdji D, Tixier-Vidal A (1980) The effect of 17 beta-estradiol on thyroliberin responsiveness in GH3/B6 rat prolactin cells. Mol Cell Endocrinol 18:123–136

    Google Scholar 

  5. Davis PD, Hill CH, Keech E, Lawton G, Nixon JS, Sedgwick AD, Wadsworth J, Westmacott D, Wilkinson SE (1989) Potent selective inhibitors of protein kinase C. FEES Lett 259:1–3

    Google Scholar 

  6. Dufy B, Jaken S, Barker JL (1987) Intracellular Ca2+-dependent protein kinase C activation mimics delayed effects of thyrotropin-releasing hormone on clonal pituitary cell excitability. Endocrinology 121:793–802

    Google Scholar 

  7. Gammon CM, Oxford GS, Allen AC, McCarthy KD, Morell P (1989) Diacylglycerol modulates action potential frequency in GH3 pituitary cells: correlative biochemical and electrophysiological studies. Brain Res 479:217–224

    Google Scholar 

  8. Gershengorn MC (1986) Mechanisms of thyrotropin-releasing hormone stimulation of pituitary hormone secretion. Annu Rev Physiol 48:512–526

    Google Scholar 

  9. Gershengorn MC (1989) Role of inositol lipid second messengers in regulation of secretion: studies of thyrotropin-releasing hormone action in pituitary cells. In: Oxford GS, Armstrong CM (eds) Secretion and its control. Rockefeller University Press, New York, pp 1–15

    Google Scholar 

  10. Gordeladze JO, Bjøro T, Torjesen PA, Østberg BC, Haug E, Gautvik KM (1989) Protein kinase C stimulates adenylate cyclase activity in prolactin-secreting rat adenoma (GH4C1) pituicytes by inactivating the inhibitory GTP-binding protein Gi. Eur J Biochem 183:397–406

    Google Scholar 

  11. Grynkiewicz G, Poenie M, Tsien RY (1985) A new generation of calcium indicators with greatly improved fluorescence properties. J Biol Sci 260:3440–3450

    Google Scholar 

  12. Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100

    Google Scholar 

  13. Hedlund B, Dufy B, Barker JL (1988) Vasoactive intestinal polypeptide alters GH3/B6 pituitary cell excitability. Pflügers Arch 411:173–179

    Google Scholar 

  14. Horn R, Marty A (1988) Muscarinic activation of ionic currents measured by a new whole-cell recording method. J Gen Physiol 92:145–159

    Google Scholar 

  15. Hsieh KP, Martin TFJ (1992) Thyrotropin-releasing hormone and gonadotropin-releasing hormone receptors activate phospholipase C by coupling to the guanosine triphosphate-binding proteins Gq and G11. Mol Endocrinol 6:1673–1681

    Google Scholar 

  16. Kolesnick RN (1989) Thyrotropin-releasing hormone and phorbol esters stimulate sphingomyelin syntheses in GH3 pituitary cells. J Biol Chem 264:11 688–11 692

    Google Scholar 

  17. Lucas DO, Bajjalieh SM, Kowalchyk JA, Martin TFJ (1985) Direct stimulation by thyrotropin-releasing hormone (TRH) of polyphosphoinositide hydrolysis in GH3 cell membranes by a guanine nucleotide-mediated mechanism. Biochem Biophys Res Commun 132:721–728

    Google Scholar 

  18. Martin TFJ (1992) Calcitonin peptide inhibition of TRH-stimulated prolactin secretion. TEM 3:82–85

    Google Scholar 

  19. Martin TFJ, Bajjalieh SM, Lucas DO, Kowalchyk JA (1986) Thyrotropin-releasing hormone stimulation of polyphosphoinositide hydrolysis in GH3 cell membranes is GTP dependent but insensitive to cholera or pertussis toxin. J Biol Chem 261:10 141–10 149

    Google Scholar 

  20. Martin TFJ, Hsieh K-P, Porter BW (1990) The sustained second phase of hormone-stimulated diacylglycerol accumulation does not activate protein kinase C in GH3 cells. J Biol Chem 265:7623–7631

    Google Scholar 

  21. Østberg BC, Sand O, Bjøro T, Haug E (1986) The phorbol ester TPA induces hormone release and electrical activity in clonal rat pituitary cells. Acta Physiol Scand 126:517–524

    Google Scholar 

  22. Oxford GS, Wagoner PK (1989) The inactivating K+ current in GH3 pituitary cells and its modification by chemical reagents. J Physiol (Lond) 410:587–612

    Google Scholar 

  23. Ozawa S, Sand O (1986) Electrophysiology of excitable endocrine cells. Physiol Rev 66:887–952

    Google Scholar 

  24. Paulssen RH, Paulssen EJ, Gautvik KM, Gordeladze JO (1992) The thyroliberin receptor interacts directly with a stimulatory guanine-nucleotide-binding protein in the activation of adenylyl cyclase in GH3 rat pituitary tumour cells. Eur J Biochem 204:413–418

    Google Scholar 

  25. de la Peña P, Delgado LM, del Camino D, Barros F (1992) Cloning and expression of the thyrotropin-releasing hormone receptor from GH3 rat anterior pituitary cells. Biochem J 284:891–899

    Google Scholar 

  26. Ramsdell JS (1990) Induction of distinct phenotypes in clonal and variant GH4 pituitary cells. In Vitro Cell Dev Biol 26:250–258

    Google Scholar 

  27. Ronning SA, Martin TFJ (1986) Characterisation of phorbol ester- and diacylglycerol-stimulated secretion in permeable GH3 pituitary cells. J Biol Chem 261:7840–7845

    Google Scholar 

  28. Rosenthal W, Hescheler J, Hinsch K-D, Spicher K, Trautwein W, Schultz G (1988) Cyclic AMP-independent, dual regulation of voltage-dependent Ca2+ currents by LHRH and somatostatin in a pituitary cell line. EMBO J 7:1627–1633

    Google Scholar 

  29. Smrcka AV, Hepler JR, Brown KO, Steinweis PC (1991) Regulation of polyphosphoinositide-specific phospholipase C activity by purified Gq. Science 251:804–807

    Google Scholar 

  30. Straub RE, Frech GC, Joho RH, Gershengorn MC (1990) Expression cloning of a cDNA encoding the mouse pituitary thyrotropin-releasing hormone receptor. Proc Natl Acad Sci USA 87:9514–9518

    Google Scholar 

  31. Taylor SJ, Chae HZ, Rhee SG, Exton JH (1991) Activation of the β1 isozyme of phospholipase C by α subunits of the Gq class of G proteins. Nature 350:516–518

    Google Scholar 

  32. Yajima Y, Akita Y, Saito T (1988) Effects of cholera toxin on the coupling of thyrotropin-releasing hormone to a guanine nucleotide-binding protein in cultured GH3 cells. Mol Pharmacol 33:592–597

    Google Scholar 

  33. Yatani A, Codina J, Sekura RD, Birnbaumer L, Brown A (1987) Reconstitution of somatostatin and muscarinic receptor mediated stimulation of K+ channels by isolated GK protein in clonal rat anterior pituitary cell membranes. Mol Endocrinol 1:283–289

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Physiologisches Institut, UKE, Martinistrasse 52, D-20246, Hamburg, Germany

    C. K. Bauer, I. Kubasov & J. R. Schwarz

  2. Department of Neurobiology, AFRC Institute of Animal Physiology and Genetics Research, CB2 4AT, Babraham, Cambridge, UK

    I. Davison & W. T. Mason

Authors
  1. C. K. Bauer
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. I. Davison
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. I. Kubasov
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. J. R. Schwarz
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. W. T. Mason
    View author publications

    You can also search for this author in PubMed Google Scholar

Additional information

On leave from Uchtomsky-Institute, St. Petersburg University, Russia

Rights and permissions

Reprints and permissions

About this article

Cite this article

Bauer, C.K., Davison, I., Kubasov, I. et al. Different G proteins are involved in the biphasic response of clonal rat pituitary cells to thyrotropin-releasing hormone. Pflügers Arch 428, 17–25 (1994). https://doi.org/10.1007/BF00374747

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF00374747

Key words

Search

Navigation