title: Serotoninergic control of glycinergic inhibitory postsynaptic currents in rat hypoglossal motoneurons.
abstract: This report presents the results of a study of the frequency potentiation of inhibitory postsynaptic currents (IPSCs) in hypoglossal motoneurons and its modulation by serotonin. A release-site model of synaptic plasticity was used to characterize the frequency-related potentiation of evoked IPSCs. Data were obtained to determine if the frequency potentiation of IPSCs occurs as a consequence of a low baseline quantal content of evoked IPSCs using whole cell patch-clamp recordings from hypoglossal motoneurons in the neonatal rat brainstem slice preparation. In these motoneurons, EPSCs and GABAergic IPSCs were blocked by the application of CNQX, AP-5 and bicuculline. Glycinergic IPSCs were evoked by threshold stimulation of inhibitory neurons in the nucleus of Roller, which is located ventro-lateral to the hypoglossal nucleus. IPSC responses to trains of stimuli were recorded in control solutions and in solutions containing serotonin, which is known to reduce IPSPs in this preparation. The amplitude of non-potentiated IPSCs was reduced and their frequency potentiation was enhanced when serotonin was added to the bath. These data were examined using a release-site model of synaptic plasticity in which facilitation is attributed to a time-dependent increase in the probability of transmitter release; depression is attributed to a time-dependent decrease in the number of sites available for release. Using this model, the effect of serotonin on frequency potentiation was explained by a combination of a reduction in the baseline probability of transmitter release and an increase in the time constant of decay of the increase in probability of release that follows a stimulus.
authors.affiliation: WebSciences International, Los Angeles, CA 90024, USA.
authors.forename: John K
authors.initials: JK
authors.lastname: Engelhardt
authors.forename: Valentina
authors.initials: V
authors.lastname: Silveira
authors.forename: Francisco R
authors.initials: FR
authors.lastname: Morales
authors.forename: Ines
authors.initials: I
authors.lastname: Pose
authors.forename: Michael H
authors.initials: MH
authors.lastname: Chase
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001933:Brain Stem / Q000187:drug effects / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005998:Glycine / Q000378:metabolism*; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008959:Models, Neurological; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
chemical_list: D012701:Serotonin; D005998:Glycine
references.citation: J Neurophysiol. 2001 Aug;86(2):565-74
references.pmid: 11495932
references.citation: Brain Res. 1991 May 24;549(2):346-9
references.pmid: 1884229
references.citation: Annu Rev Neurosci. 1989;12:13-31
references.pmid: 2648947
references.citation: J Neurophysiol. 1997 Jun;77(6):2910-24
references.pmid: 9212246
references.citation: J Neurosci Methods. 2000 Jun 30;99(1-2):25-35
references.pmid: 10936639
references.citation: J Neurophysiol. 1995 Mar;73(3):1192-201
references.pmid: 7608765
references.citation: J Neurosci Methods. 2002 Oct 30;120(2):131-43
references.pmid: 12385763
references.citation: Brain Res. 2004 Mar 19;1001(1-2):1-12
references.pmid: 14972649
references.citation: Neuroreport. 1996 Nov 25;7(18):3081-5
references.pmid: 9116245
references.citation: Eur J Neurosci. 2005 Dec;22(12):3195-204
references.pmid: 16367786
references.citation: Neurosci Res. 2002 Dec;44(4):343-56
references.pmid: 12445623
references.citation: Brain Res. 1991 Dec 20;567(2):346-9
references.pmid: 1817740
references.citation: Brain Res. 2004 Aug 20;1018(1):26-31
references.pmid: 15262201
references.citation: J Neurosci. 1999 Nov 1;19(21):9508-18
references.pmid: 10531453
references.citation: Brain Res. 1982 Apr 8;237(1):232-7
references.pmid: 7074357
references.citation: J Comp Neurol. 1997 Mar 3;379(1):150-70
references.pmid: 9057118
references.citation: Neuron. 1997 Jun;18(6):995-1008
references.pmid: 9208866
references.citation: Neuroscience. 2010 Feb 17;165(4):1390-401
references.pmid: 19963045
references.citation: J Neurosci. 1999 Jun 1;19(11):4293-304
references.pmid: 10341233
references.citation: J Neurosci. 2000 Feb 15;20(4):1374-85
references.pmid: 10662828
references.citation: Brain Res. 1982 Nov 18;251(2):259-76
references.pmid: 7139326
references.citation: J Comp Neurol. 1993 Oct 1;336(1):53-65
references.pmid: 8254113
references.citation: Prog Brain Res. 2008;172:233-64
references.pmid: 18772036
references.citation: J Physiol. 1996 Feb 1;490 ( Pt 3):745-58
references.pmid: 8683472
references.citation: J Neurophysiol. 1999 Jan;81(1):140-8
references.pmid: 9914275
references.citation: Neuroscience. 2006 Sep 29;142(1):37-47
references.pmid: 16891059
references.citation: Annu Rev Physiol. 2002;64:355-405
references.pmid: 11826273
references.citation: Proc Biol Sci. 2009 Jan 7;276(1654):99-108
references.pmid: 18782747
references.citation: Brain Res. 1990 Dec 10;535(2):339-42
references.pmid: 2073613