The Journal of Physiological Sciences
Online ISSN : 1880-6562
Print ISSN : 1880-6546
ISSN-L : 1880-6546
Regular Papers
Rat GnRH Neurons Exhibit Large Conductance Voltage- and Ca2+-Activated K+ (BK) Currents and Express BK Channel mRNAs
Yoshie HiraizumiIchiro NishimuraHirotaka IshiiNobuyuki TanakaToshiyuki TakeshitaYasuo SakumaMasakatsu Kato
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2008 Volume 58 Issue 1 Pages 21-29

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Abstract

Gonadotropin-releasing hormone (GnRH) neurons form the final common pathway for the central regulation of reproduction. As in other neurons, the discharge pattern of action potentials is important for these neurons to function properly. Therefore it is important to elucidate the expression patterns of various types of ion channels in these neurons because they determine cell excitability. To date, voltage-gated Ca2+ channels and SK channels have been reported to be expressed in rat GnRH neurons. In this study, we focused on K+ channels and analyzed their expression in primary cultured GnRH neurons, prepared from GnRH-EGFP transgenic rats, by means of perforated patch-clamp recordings. GnRH neurons exhibited delayed-rectifier K+ currents and large conductance voltage- and Ca2+-activated K+ (BK) currents. Moreover, multicell RT-PCR (reverse transcriptase–polymerase chain reaction) experiments revealed the expression of BK channel mRNAs (α, β1, β2, and β4). The results show the presence of delayed-rectifier K+ currents and BK currents besides previously reported slow afterhyperpolarization currents. These currents control the action potential repolarization and probably also the firing pattern, thereby regulating the cell excitability of GnRH neurons.

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© 2008 by The Physiological Society of Japan
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