title: Postinhibitory rebound spikes are modulated by the history of membrane hyperpolarization in the SCN.
abstract: The suprachiasmatic nucleus (SCN) of the hypothalamus regulates biological circadian time thereby directly impacting numerous physiological processes. The SCN is composed almost exclusively of gamma-aminobutyric acid (GABA)ergic neurons, many of which synapse with other GABAergic cells in the SCN to exert an inhibitory influence on their postsynaptic targets for most, if not all, phases of the circadian cycle. The overwhelmingly GABAergic nature of the SCN, along with its internal connectivity properties, provide a strong model to examine how inhibitory neurotransmission generates output signals. In the present work we show that hyperpolarizations that range from 5 to 1000 ms elicit rebound spikes in 63% of all SCN neurons tested in voltage-clamp in the SCN of adult rats and hamsters. In current-clamp recordings, hyperpolarizations led to rebound spike formation in all cells; however, low-amplitude or short-duration current injections failed to consistently activate rebound spikes. Increasing the duration of hyperpolarization from 5 to 1000 ms is strongly and positively correlated with enhanced spike probability. Additionally, the magnitude of hyperpolarization exerts a strong influence on both the amplitude of the spike, as revealed by voltage-clamp recordings, and the latency to peak current obtained in either voltage- or current-clamp mode. Our results suggest that SCN neurons may use rebound spikes as one means of producing output signals from a largely interconnected network of GABAergic neurons.
authors.affiliation: CROET, OHSU, Portland, OR, USA.
authors.forename: Liisa A
authors.initials: LA
authors.lastname: Tremere
authors.forename: Raphael
authors.initials: R
authors.lastname: Pinaud
authors.forename: Robert P
authors.initials: RP
authors.lastname: Irwin
authors.forename: Charles N
authors.initials: CN
authors.lastname: Allen
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D006224:Cricetinae; D008012:Lidocaine / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008647:Mesocricetus; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D005680:gamma-Aminobutyric Acid; D008012:Lidocaine
references.citation: Pflugers Arch. 1993 Oct;425(1-2):109-16
references.pmid: 7903809
references.citation: J Neurophysiol. 2002 Mar;87(3):1348-62
references.pmid: 11877509
references.citation: Brain Res Dev Brain Res. 1995 May 26;86(1-2):187-202
references.pmid: 7656412
references.citation: Neuroscience. 2004;123(1):87-99
references.pmid: 14667444
references.citation: Vis Neurosci. 2007 Sep-Oct;24(5):709-31
references.pmid: 17908349
references.citation: J Neurophysiol. 2002 Nov;88(5):2821-33
references.pmid: 12424315
references.citation: J Neurosci. 2003 Feb 15;23(4):1441-50
references.pmid: 12598633
references.citation: Neurosci Lett. 1993 Feb 5;150(1):112-6
references.pmid: 8097023
references.citation: Proc Natl Acad Sci U S A. 1972 Jun;69(6):1583-6
references.pmid: 4556464
references.citation: J Biol Rhythms. 1999 Apr;14(2):126-30
references.pmid: 10194649
references.citation: Proc Natl Acad Sci U S A. 1979 Nov;76(11):5962-6
references.pmid: 293695
references.citation: J Physiol. 2001 Dec 15;537(Pt 3):853-69
references.pmid: 11744760
references.citation: Proc Natl Acad Sci U S A. 2006 Dec 12;103(50):19188-93
references.pmid: 17138670
references.citation: J Neurophysiol. 2004 Jan;91(1):267-73
references.pmid: 14715720
references.citation: Neuron. 2000 Jan;25(1):123-8
references.pmid: 10707977
references.citation: Neuron. 1995 Apr;14(4):697-706
references.pmid: 7718233
references.citation: J Physiol. 2002 Jan 1;538(Pt 1):227-51
references.pmid: 11773331
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2003 Sep;68(3 Pt 1):031907
references.pmid: 14524803
references.citation: Nature. 2002 Mar 21;416(6878):286-90
references.pmid: 11875398
references.citation: Cell. 2007 May 4;129(3):605-16
references.pmid: 17482552
references.citation: J Neurosci. 1999 Mar 15;19(6):2152-60
references.pmid: 10066268
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2004 Jul;70(1 Pt 1):011908
references.pmid: 15324089
references.citation: J Neurophysiol. 2002 Feb;87(2):834-44
references.pmid: 11826050
references.citation: Neurosci Lett. 1993 Jul 23;157(2):199-202
references.pmid: 8233053
references.citation: Neuroscience. 2003;120(1):65-73
references.pmid: 12849741
references.citation: J Neurophysiol. 1997 Oct;78(4):2217-20
references.pmid: 9325388
references.citation: Brain Res. 1995 Jul 31;687(1-2):125-32
references.pmid: 7583297
references.citation: Nat Neurosci. 1998 Dec;1(8):708-13
references.pmid: 10196587
references.citation: J Physiol. 1998 Feb 1;506 ( Pt 3):775-93
references.pmid: 9503337
references.citation: Brain Res. 2000 Jun 2;866(1-2):247-56
references.pmid: 10825500
references.citation: Science. 1986 Nov 7;234(4777):738-40
references.pmid: 3775364
references.citation: Brain Res. 1972 Jul 13;42(1):201-6
references.pmid: 5047187
references.citation: J Neurosci. 2003 Jun 15;23(12):4831-41
references.pmid: 12832505
references.citation: Eur J Neurosci. 2004 May;19(10):2791-8
references.pmid: 15147312
references.citation: J Neurosci. 2003 Mar 1;23(5):1593-604
references.pmid: 12629163
references.citation: J Neurosci. 2004 Sep 15;24(37):7985-98
references.pmid: 15371499
references.citation: J Neurosci. 2006 Apr 19;26(16):4247-55
references.pmid: 16624945
references.citation: Nature. 1997 Jun 5;387(6633):598-603
references.pmid: 9177347
references.citation: J Neurophysiol. 2004 Jul;92(1):311-9
references.pmid: 14973316
references.citation: Brain Res Bull. 1990 Jul;25(1):93-8
references.pmid: 2207720
references.citation: Neuroscience. 1984 Nov;13(3):761-7
references.pmid: 6098858
references.citation: J Neurosci. 1999 Aug 1;19(15):6700-11
references.pmid: 10414999
references.citation: Neuroscience. 1995 Feb;64(3):813-9
references.pmid: 7715789
references.citation: Curr Biol. 2005 May 24;15(10):886-93
references.pmid: 15916945
references.citation: J Neurophysiol. 2003 Sep;90(3):1438-48
references.pmid: 12750413
references.citation: J Neurophysiol. 2003 Sep;90(3):1589-97
references.pmid: 12966176
references.citation: Pflugers Arch. 2006 Apr;452(1):7-15
references.pmid: 16283205