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This Article Full Text Full Text (PDF) All Versions of this Article: 586/13/3097    most recent jphysiol.2008.153148v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Zemkova, H. W. Articles by Stojilkovic, S. S. PubMed PubMed Citation Articles by Zemkova, H. W. Articles by Stojilkovic, S. S. Related Collections Cellular Related Article

¹ Section on Cellular Signalling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development (NICHD), National Institutes of Health, Bethesda, MD 20892-4510, USA

Anterior pituitary cells express -aminobutyric acid (GABA)-A receptor-channels, but their structure, distribution within the secretory cell types, and nature of action have not been clarified. Here we addressed these questions using cultured anterior pituitary cells from postpubertal female rats and immortalized T3-1 and GH₃ cells. Our results show that mRNAs for all GABA_A receptor subunits are expressed in pituitary cells and that 1/β1 subunit proteins are present in all secretory cells. In voltage-clamped gramicidin-perforated cells, GABA induced dose-dependent increases in current amplitude that were inhibited by bicuculline and picrotoxin and facilitated by diazepam and zolpidem in a concentration-dependent manner. In intact cells, GABA and the GABA_A receptor agonist muscimol caused a rapid and transient increase in intracellular calcium, whereas the GABA_B receptor agonist baclofen was ineffective, suggesting that chloride-mediated depolarization activates voltage-gated calcium channels. Consistent with this finding, RT-PCR analysis indicated high expression of NKCC1, but not KCC2 cation/chloride transporter mRNAs in pituitary cells. Furthermore, the GABA_A channel reversal potential for chloride ions was positive to the baseline membrane potential in most cells and the activation of ion channels by GABA resulted in depolarization of cells and modulation of spontaneous electrical activity. These results indicate that secretory pituitary cells express functional GABA_A receptor-channels that are depolarizing.

(Received 25 February 2008; accepted after revision 28 April 2008; first published online 1 May 2008)
Corresponding author S. S. Stojilkovic: NICHD; Bldg. 49, Room 6A-36, 49 Convent Drive, Bethesda, MD 20892-4510, USA. Email: stankos{at}helix.nih.gov

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				M. Kreft and R. Zorec Anterior pituitary cells excited by GABA J. Physiol., July 1, 2008; 586(13): 3023 - 3024. [Full Text] [PDF]