17beta;-estradiol regulation of T-type calcium channels in gonadotropin-releasing hormone neurons

Chunguang Zhang, Martha A. Bosch, Elizabeth A. Rick, Martin Kelly, Oline Ronnekleiv

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

T-type calcium channels are responsible for generating low-threshold spikes that facilitate burst firing and neurotransmitter release in neurons. Gonadotropin-releasing hormone (GnRH) neurons exhibit burst firing, but the underlying conductances are not known. Previously, we found that 17β-estradiol (E2) increases T-type channel expression and excitability of hypothalamic arcuate nucleus neurons. Therefore, we used ovariectomized oil- or E2-treated EGFP (enhanced green fluorescent protein)-GnRH mice to explore the expression and E2 regulation of T-type channels in GnRH neurons. Based on single-cell reverse transcriptase-PCR and real-time PCR quantification of the T-type channel α1 subunits, we found that all three subunits were expressed in GnRH neurons, with expression levels as follows: Cav3.3 ≥ Cav3.2 ≤ Cav3.1. The mRNA expression of the three subunits was increased with surge-inducing levels of E2 during the morning. During the afternoon, Cav3.3mRNAexpression remained elevated, whereas Cav3.1 and Cav3.2 were decreased. The membrane estrogen receptor agonist STX increased the expression of Cav3.3 but not Cav3.2 in GnRH neurons. Whole-cell patch recordings in GnRH neurons revealed that E2 treatment significantly augmented T-type current density at both time points and increased the rebound excitation during the afternoon. Although E2 regulated the mRNA expression of all three subunits in GnRH neurons, the increased expression combined with the slower inactivation kinetics of the T-type current indicates that Cav3.3 may be the most important for bursting activity associated with the GnRH/LH (luteinizing hormone) surge. The E2-induced increase in mRNA expression, which depends in part on membrane-initiated signaling, leads to increased channel function and neuronal excitability and could be a mechanism by which E2 facilitates burst firing and cyclic GnRH neurosecretion.

Original languageEnglish (US)
Pages (from-to)10552-10562
Number of pages11
JournalJournal of Neuroscience
Volume29
Issue number34
DOIs
StatePublished - Aug 26 2009

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T-Type Calcium Channels
Gonadotropin-Releasing Hormone
Estradiol
Neurons
Messenger RNA
Neurosecretion
Arcuate Nucleus of Hypothalamus
Membranes
Patch-Clamp Techniques
Luteinizing Hormone
Reverse Transcriptase Polymerase Chain Reaction
Neurotransmitter Agents
Real-Time Polymerase Chain Reaction
Estrogens
Oils

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

17beta;-estradiol regulation of T-type calcium channels in gonadotropin-releasing hormone neurons. / Zhang, Chunguang; Bosch, Martha A.; Rick, Elizabeth A.; Kelly, Martin; Ronnekleiv, Oline.

In: Journal of Neuroscience, Vol. 29, No. 34, 26.08.2009, p. 10552-10562.

Research output: Contribution to journalArticle

Zhang, Chunguang ; Bosch, Martha A. ; Rick, Elizabeth A. ; Kelly, Martin ; Ronnekleiv, Oline. / 17beta;-estradiol regulation of T-type calcium channels in gonadotropin-releasing hormone neurons. In: Journal of Neuroscience. 2009 ; Vol. 29, No. 34. pp. 10552-10562.
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