HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 69/6/1914    most recent biolreprod.103.019265v1 Alert me when this article is cited Alert me if a correction is posted Citation Map 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 Citing Articles via Google Scholar Google Scholar Articles by Nunemaker, C. S. Articles by Moenter, S. M. Search for Related Content PubMed PubMed Citation Articles by Nunemaker, C. S. Articles by Moenter, S. M. Agricola Articles by Nunemaker, C. S. Articles by Moenter, S. M.

Calcium Current Subtypes in GnRH Neurons¹

Departments of Internal Medicine and Cell Biology, University of Virginia, Charlottesville, Virginia 22908

Calcium plays roles in excitability, rhythm generation, and neurosecretion. Identifying channel subtypes that regulate calcium influx is thus important to understanding rhythmic GnRH secretion, which is a prerequisite for reproduction. Whole-cell voltage-clamp recordings were made from short-term dissociated GnRH adult ovariectomized (OVX) mice (n = 21) to identify channel subtypes that carry calcium current using selective channel blockers and voltage characteristics. Low-voltage activated (LVA) currents were not observed in 42 GnRH neurons tested, although most non-GnRH neurons (4/6) displayed LVA current. The L-type component of the high-voltage activated (HVA) calcium current was 25% ± 2%. The remaining HVA calcium current passed through N-type (27% ± 3%), P-type (15% ± 1%), Q-type (18% ± 3%), and R-type (15% ± 1%) channels. Because these data differ substantially from reports on cultured GnRH neurons, which may represent reproductively immature models, we also examined GnRH neurons from gonadal-intact young (Postnatal Days 4–10, n = 8 mice) mice. LVA currents were still rare (2/28) in young mice. Although the same HVA components were observed, the proportions were shifted toward significantly more L-type and less N-type current, suggesting a possible developmental shift in calcium currents in GnRH neurons. These data suggest that calcium channel subtypes in GnRH neurons prepared in the short term from brain slices differ substantially from those in long-term cultured GnRH models. These findings provide a vital foundation to examine the role of calcium channels in the secretory and rhythmic machinery of GnRH neurons.

¹ Supported by HD34860 and the National Institute of Child Health and Human Development/National Institutes of Health through cooperative agreement U54HD28934 as part of the center's program in reproductive research.

² Correspondence: Suzanne M. Moenter, Department of Internal Medicine, University of Virginia, P.O. Box 800578, Charlottesville, VA 22908. FAX: 434 982 0088; smm4n{at}virginia.edu

³ Current address: Department of Pharmacology and Toxicology, Medical College of Virginia Campus, Virginia Commonwealth University, P.O. Box 980524, Richmond, VA 23298

⁴ Current address: University of Miami School of Medicine, Department of Physiology and Biophysics, Miami, FL 33101

This article has been cited by other articles:

				D. J. Spergel Calcium and Small-Conductance Calcium-Activated Potassium Channels in Gonadotropin-Releasing Hormone Neurons before, during, and after Puberty Endocrinology, May 1, 2007; 148(5): 2383 - 2390. [Abstract] [Full Text] [PDF]

				N. Chattopadhyay, K.-H. Jeong, S. Yano, S. Huang, J. L. Pang, X. Ren, E. Terwilliger, U. B. Kaiser, P. M. Vassilev, M. R. Pollak, et al. Calcium receptor stimulates chemotaxis and secretion of MCP-1 in GnRH neurons in vitro: potential impact on reduced GnRH neuron population in CaR-null mice Am J Physiol Endocrinol Metab, February 1, 2007; 292(2): E523 - E532. [Abstract] [Full Text] [PDF]

				J. Qiu, M. A. Bosch, K. Jamali, C. Xue, M. J. Kelly, and O. K. Ronnekleiv Estrogen Upregulates T-Type Calcium Channels in the Hypothalamus and Pituitary J. Neurosci., October 25, 2006; 26(43): 11072 - 11082. [Abstract] [Full Text] [PDF]

				M. Kato, N. Tanaka, S. Usui, and Y. Sakuma The SK channel blocker apamin inhibits slow afterhyperpolarization currents in rat gonadotropin-releasing hormone neurones J. Physiol., July 15, 2006; 574(2): 431 - 442. [Abstract] [Full Text] [PDF]

				C. B. Roberts, J. A. Best, and K. J. Suter Dendritic Processing of Excitatory Synaptic Input in Hypothalamic Gonadotropin Releasing-Hormone Neurons Endocrinology, March 1, 2006; 147(3): 1545 - 1555. [Abstract] [Full Text] [PDF]

				K. Haneda and Y. Oka Selective Modulation of Voltage-Gated Calcium Channels in the Terminal Nerve Gonadotropin-Releasing Hormone Neurons of a Teleost, the Dwarf Gourami (Colisa lalia) Endocrinology, October 1, 2004; 145(10): 4489 - 4499. [Abstract] [Full Text] [PDF]