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Journal of Computational Neuroscience

, Volume 22, Issue 2, pp 211–222 | Cite as

Low dose of dopamine may stimulate prolactin secretion by increasing fast potassium currents

  • Joël TabakEmail author
  • Natalia Toporikova
  • Marc E. Freeman
  • Richard Bertram
Article

Abstract

Dopamine (DA) released from the hypothalamus tonically inhibits pituitary lactotrophs. DA (at micromolar concentration) opens potassium channels, hyperpolarizing the lactotrophs and thus preventing the calcium influx that triggers prolactin hormone release. Surprisingly, at concentrations ∼1000 lower, DA can stimulate prolactin secretion. Here, we investigated whether an increase in a K+ current could mediate this stimulatory effect. We considered the fast K+ currents flowing through large-conductance BK channels and through A-type channels. We developed a minimal lactotroph model to investigate the effects of these two currents. Both I BK and I A could transform the electrical pattern of activity from spiking to bursting, but through distinct mechanisms. I BK always increased the intracellular Ca2+ concentration, while I A could either increase or decrease it. Thus, the stimulatory effects of DA could be mediated by a fast K+ conductance which converts tonically spiking cells to bursters. In addition, the study illustrates that a heterogeneous distribution of fast K+ conductances could cause heterogeneous lactotroph firing patterns.

Keywords

Lactotrophs Bursting Calcium Fast/slow analysis 

Notes

Acknowledgment

This work was supported by NIH grants DA-19356 and DK-43200.

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Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • Joël Tabak
    • 1
    Email author
  • Natalia Toporikova
    • 2
  • Marc E. Freeman
    • 1
  • Richard Bertram
    • 2
  1. 1.Department of Biological ScienceFlorida State UniversityTallahasseeUSA
  2. 2.Department of MathematicsFlorida State UniversityTallahasseeUSA

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