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: 93/6/3157    most recent 00770.2004v1 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 ISI Web of Science 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 ISI Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Bramley, J. R. Articles by Dudek, F. E. Search for Related Content PubMed PubMed Citation Articles by Bramley, J. R. Articles by Dudek, F. E.

5-HT_1B Receptor-Mediated Presynaptic Inhibition of GABA Release in the Suprachiasmatic Nucleus

Department of Biomedical Sciences, Anatomy and Neurobiology Section, Colorado State University, Fort Collins, Colorado

Submitted 29 July 2004; accepted in final form 11 February 2005

The suprachiasmatic nucleus (SCN) receives a dense serotonergic innervation that modulates photic input to the SCN via serotonin 1B (5-HT_1B) presynaptic receptors on retinal glutamatergic terminals. However, the majority of 5-HT_1B binding sites in the SCN are located on nonretinal terminals and most axonal terminals in the SCN are GABAergic. We therefore tested the hypothesis that 5-HT_1B receptors might also be located on SCN GABAergic terminals by examining the effects of the highly selective 5-HT_1B receptor agonist CP-93,129 on SCN miniature inhibitory postsynaptic currents (mIPSCs). Whole cell patch-clamp recordings of mIPSCs were obtained from rat and mouse SCN neurons in hypothalamic slices. Using CsCl-containing microelectrodes with QX314, we isolated mPSCs that were sensitive to the GABA_A receptor antagonist, bicuculline. Bath application of CP-93,129 (1 µM) decreased the frequency of mIPSCs by an average of 22% (n = 7) in rat SCN neurons and by an average of 30% (n = 8) in mouse SCN neurons with no clear effect on mIPSC amplitude. In mice lacking functional 5-HT_1B receptors, CP-93,129 (1 µM) had no clear effect on the frequency or the amplitude of mIPSCs recorded in any of the cells tested (n = 4). The decrease in the frequency of mIPSCs of SCN neurons produced by the selective 5-HT_1B receptor agonist CP-93,129 is consistent with the interpretation that 5-HT_1B receptors are located on GABA terminals in the SCN and that 5-HT inhibits GABA release via a 5-HT_1B presynaptic receptor-mediated mechanism.

This article has been cited by other articles:

				K. B. Fink and M. Gothert 5-HT Receptor Regulation of Neurotransmitter Release Pharmacol. Rev., December 1, 2007; 59(4): 360 - 417. [Abstract] [Full Text] [PDF]

				M. G. Moldavan, R. P. Irwin, and C. N. Allen Presynaptic GABAB Receptors Regulate Retinohypothalamic Tract Synaptic Transmission by Inhibiting Voltage-Gated Ca2+ Channels J Neurophysiol, June 1, 2006; 95(6): 3727 - 3741. [Abstract] [Full Text] [PDF]

				P. J. Sollars, M. D. Ogilvie, A. M. Simpson, and G. E. Pickard Photic Entrainment Is Altered in the 5-HT1B Receptor Knockout Mouse J Biol Rhythms, February 1, 2006; 21(1): 21 - 32. [Abstract] [PDF]