The Effects of Hypokalaemia on the Hormone Exocytosis in Adenohypophysis and Prolactinoma Cell Culture Model Systems

Z. Molnár; R. Pálföldi; A. László; M. Radács; M. László; P. Hausinger; L. Tiszlavicz; Z. Rázga; Z. Valkusz; M. Gálfi

doi:10.1055/s-0034-1383580

Experimental and Clinical Endocrinology & Diabetes, Inhaltsverzeichnis

Exp Clin Endocrinol Diabetes 2014; 122(10): 575-581
DOI: 10.1055/s-0034-1383580

Article

The Effects of Hypokalaemia on the Hormone Exocytosis in Adenohypophysis and Prolactinoma Cell Culture Model Systems

Z. Molnár

¹Department of Environmental Biology and Education, Gyula Juhász Faculty of Education, Institute of Applied Science,University of Szeged, Szeged, Hungary

,

R. Pálföldi

²Department of Pulmonology, Faculty of Medicine, University of Szeged, Szeged, Hungary

,

A. László

³Department of Medical Physics and Informatics, Faculty of Medicine, University of Szeged, Szeged, Hungary

,

M. Radács

¹Department of Environmental Biology and Education, Gyula Juhász Faculty of Education, Institute of Applied Science,University of Szeged, Szeged, Hungary

,

M. László

¹Department of Environmental Biology and Education, Gyula Juhász Faculty of Education, Institute of Applied Science,University of Szeged, Szeged, Hungary

,

P. Hausinger

⁴Invasive Cardiology Department, Second Department of Internal Medicine and Cardiology, Faculty of Medicine, University of Szeged, Szeged, Hungary

,

L. Tiszlavicz

⁵Department of Pathology, Faculty of Medicine, University of Szeged, Szeged, Hungary

,

Z. Rázga

⁵Department of Pathology, Faculty of Medicine, University of Szeged, Szeged, Hungary

,

Z. Valkusz

⁶Endocrine Unit of First Department of Internal Medicine, Faculty of Medicine, University of Szeged, Szeged, Hungary

,

M. Gálfi

¹Department of Environmental Biology and Education, Gyula Juhász Faculty of Education, Institute of Applied Science,University of Szeged, Szeged, Hungary

› Institutsangaben

Abstract

The extracellular ion milieu determines the exocytosis mechanism that is coupled to spontaneous electrical activity. The K⁺ ion plays crucial role in this mechanism: as the potassium current is associated with membrane hyperpolarization and hormone release through protein cascade activation. The primary aim of this study was to investigate the response mechanisms of normal adenohypophysis and adenohypophyseal prolactinoma cell populations at different extracellular K⁺ levels with an otherwise isoionic milieu of all other essential ions. We focused on prolactin (PRL) and adrenocorticotrophic hormone (ACTH) release.

In our experimental study, female Wistar rats (n=20) were treated with estrone-acetate (150 μg/kg b.w./week) for 6 months to induce prolactinomas in the adenohypophysis. Primary, monolayer cell cultures were prepared by enzymatic and mechanical digestion. PRL and ACTH hormone presence was measured by radioimmunoassay or immuno-chemiluminescence assay. Immunocytochemistry was used to assess the apoptotic cells.

Differences between the effects of hypokalaemia on normal adenohypophysis cultures and prolactinoma cell populations were investigated. Significant alteration (p<0.001, n=10) in hormone exocytosis was detected in K⁺ treated adenohypophyseal and prolactinoma cell cultures compared to untreated groups. Immunocytochemistry showed that Bcl-2 expression was reduced under hypokalaemic conditions.

The decrease in hormone exocytosis was tightly correlated to the extracellular K⁺ in both cell types, leading to the conclusion that external K⁺ may be the major factor for the inhibition of hormone release. The significant increase in hormone content in supernatant media suggests that hypokalaemia may play important role in apoptosis.

Key words

adenohypophysis cell cultures - extracellular ion milieu - hypokalaemia - prolactinoma

Volltext

Referenzen

References
1 Clapp C, Torner L, Gutierrez-Ospina G et al. The prolactin gene is expressed in the hypothalamic-neurohypophyseal system and the protein is processed into a 14 kDa fragment with activity like 16-kDa prolactin. Physiology 1994; 91: 10384-10388
2 Gozil R, Evrenkaya T, Keskil Z et al. Effects of trauma and pain on the acute anterior pituitary hormonal response. Neuropeptides 2002; 36: 46-49
3 Karaca Z, Tanriverdi F, Unluhizarci K et al. Pregnancy and pituitary disorders. Eur J Endocrinol 2010; 162: 453-475
4 Born J, Fehm HL. Hypothalamus-pituitary-adrenal activity during human sleep: a coordinating role for the limbic hippocampal system. Exp Clin Endocrinol Diabetes 1998; 106: 153-163
5 Musso CG, Oreopoulos DG. Aging and Physiological Changes of the Kidneys Including Changes in Glomerular Filtration Rate. Nephron Physiol 2011; 119: 1-5
6 Ueno H, Yoshimura M, Nakayama M et al. Clinical factors affecting serum potassium concentration in cardio-renal decompensation syndrome. Int J Cardiol 2010; 138: 174-181
7 Vaur S, Bresson-Bepoldin L, Dufy B et al. Potassium channel inhibition reduces cell proliferation in the GH3 pituitary cell line. J Cell Physiol 1998; 177: 1097-4652
8 Pancrazio JJ, Tabbara IA, Kim YI. Voltage-activated K⁺ conductance and cell proliferation in small cell-lung cancer. Anticancer Res 1993; 13: 1231-1234
9 Tsai KH, Wang WJ, Lin CW et al. NADPH oxidase-derived superoxide anion-induced apoptosis is mediated via the JNK-dependent activation of NF-kappa B in cardiomyocytes exposed to high glucose. J Cell Physiol 2012; 227: 1347-1357
10 Ramiro-Cortés Y, Guemez-Gamboa A, Morán J. Reactive oxygen species participate in the p38-mediated apoptosis induced by potassium deprivation and staurosporine in cerebellar granule neurons. Int J Biochem Cell Biol 2011; 43: 1373-1382
11 Simon H-U, Haj-Yehia A, Levi-Schaffer F. Role of reactive oxygen species (ROS) in apoptosis induction. Apoptosis 2000; 5: 415-418
12 Nakamura T, Kataoka K, Fukuda M et al. Critical role of apoptosis signal-regulating kinase 1 in aldosterone/salt-induced cardiac inflammation and fibrosis. Hypertension 2011; 54: 544-551
13 Slee EA, Adrian C, Martin SJ. Serial killers: ordering caspase activation events in apoptosis. Cell Death and Differ 1996; 6: 1067-1074
14 Ciccarelli A, Daly AF, Beckers A. The epidemiology of prolactinomas. Pituitary 2005; 8: 3-6
15 Narayanan RP, Bujawansa S, Qureshi Z et al. Hypogonadism secondary to hyperprolactinaemia: successful treatment but adverse consequences. Exp Clin Endocrinol Diabetes 2012; 120: 311-313
16 McChesney R, Sealfon SC, Tsutsumi M et al. Either isoform of the dopamine D2 receptor can mediate dopaminergic repression of the rat prolactin promoter. Mol Cell Endocrinol 1991; 79: 1-7
17 Charoenphandhu N, Teerapornpuntakit J, Methawasin M et al. Prolactin decreases expression of Runx2, osteoprotegerin, and RANKL in primary osteoblasts derived from tibiae of adult female rats. Can J Physiol Pharmacol 2008; 86: 240-248
18 Dobrović-Jenik D, Dusanek S, Milković S. Kidney damage in rats bearing an adrenocorticotropin and prolactin secreting tumor. Exp Clin Endocrinol Diabetes 1990; 96: 207-212
19 Camacho J. Ether a’ go-go potassium channels and cancer. Cancer Lett 2006; 233: 1-9
20 Edwards DP. Regulation of signal transduction pathways by estrogen and progesterone. Annu Rev Physiol 2005; 67: 335-376
21 Visser-Wisselaar HA, Van Uffelen CJC, Van Koetsveld PM et al. 17-β-estradiol dependent regulation of somatostatin receptor subtype expression in the 7315b prolactin secreting rat pituitary tumor in vitro and in vivo. Endocrinology 1997; 138: 1180-1189
22 Brann DW, Rao IM, Mahesh VB. Antagonism of estrogen-induced prolactin release by progesterone. Biol Reprod 1988; 39: 1067-1073
23 Lieberman ME, Maurer RA, Gorski J. Estrogen control of prolactin synthesis in vitro. Biochemistry 1978; 75: 5946-5949
24 Janaky T, Szabo P, Kele Z et al. Identification of oxytocin and vasopressin from neurohypophyseal cell culture. Rapid Commun Mass Spectrom 1998; 12: 1765-1768
25 Galfi M, Janaky T, Toth R et al. Effects of dopamine and dopamine-active compounds on oxytocin and vasopressin production in rat neurohypophyseal tissue cultures. Regul Pept 2001; 98: 49-54
26 Lowry OH, Rosebrough NJ, Farr AL et al. Protein measurement with the Folin phenol reagent. J Biol Chem 1951; 193: 265-275
27 Tomita T. Conductance change during the inhibitory potential in the guinea pig taenia coli. J Physiol 1972; 225: 693-703
28 Stojilkovic SS, Tabak J, Bertram R. Ion Channels and signaling in the pituitary gland. Endocr Rev 2010; 6: 845-915
29 Bauer CS, Woolley RJ, Teschemacher AG et al. Potentiation of exocytosis by phospholipase C-coupled G-protein-coupled receptors requires the priming protein Munc13-1. J Neurosci 2007; 27: 212-219
30 Freeman ME, Kanyicska B, Lerant A et al. Prolactin: Structure, function and regulation of secretion. Physiol Rev 2000; 80: 1523-1631
31 Brunger AT. Structural insights into the molecular mechanism of Ca²⁺-dependent exocytosis. Curr Opin Neurobiol 2010; 10: 293-302
32 Sherr CJ, Roberts JM. Inhibitors of mammalian G₁ cyclin-dependent kinases. Genes Dev 1995; 9: 1149-1163
33 Cooper S. Mammalian cells are not synchronized in G1-phase by starvation or inhibition: considerations of the fundamental concept of G1-phase synchronization. Cell Prolif 1998; 31: 9-16
34 Leng G, Shibuki K, Way SA. Effects of raised extracellular potassium on the excitability of, and hormone release from, the isolated rat neurohypophysis. J Physiol 1988; 399: 591-605
35 Leng G, Shibuki K. Extracellular potassium changes in the rat neurohypophysis during activation of the magnocellular neurosecretory system. J Physiol 1987; 392: 97-111
36 Robba C, Rebuffat P, Mazzocchi G et al. The possible potassium involvement in the modulation of the long-term trophic action of ACTH on the rat adrenal zona fasciculata. Exp Clin Endocrinol Diabetes 1985; 86: 371-374
37 Johnson SW, North RA. Opioids excite dopamine neurons by hyperpolarization of local interneurons. J Neurosci 1992; 12: 483-488
38 Giebisch G. Renal potassium transport: mechanisms and regulation. Am J Physiol Renal Physiol 1998; 274: 817-833
39 Ghobrial IM, Witzig TE, Adjei AA. Targeting apoptosis pathway in cancer therapy. CA-Cancer J Clin 2005; 55: 178-194
40 Verma G, Malabika D. The critical role of JNK in the ER-mitochondrial crosstalk during apoptotic cell death. J Cell Physiol 2012; 227: 1791-1795
41 Fan T-J, Han L-H, Cong R-S et al. Caspase family proteases and apoptosis. Acta Bioch Bioph Sin 2005; 37: 719-727