Nitric oxide alters GABAergic synaptic transmission in cultured hippocampal neurons.
Nitric oxide (NO) production increases during hypoxia/ischemia-reperfusion in the immature brain and is associated with neurotoxicity. NO at physiologic concentrations has been shown to modulate GABAergic (gamma-aminobutyric acid) synaptic transmission in the adult brain. However, the effects of neurotoxic concentrations of NO (relevant to hypoxia-ischemia) on GABAergic synaptic transmission remain unknown. The present study tests the hypothesis that nNOS is expressed at GABAergic synapses and that exposure to neurotoxic concentrations of NO results in enhanced GABAergic synaptic transmission in cultured hippocampal neurons (days-in-vitro 10-14) prepared from fetal rats. Using double immunocytochemistry techniques, we were able to demonstrate that nNOS is co-localized to both presynaptic and postsynaptic markers of GABAergic synapses. The effects of NO on GABAergic synaptic transmission were then studied using whole cell patch-clamp electrophysiology. Spontaneous and miniature inhibitory postsynaptic currents (sIPSCS and mIPSCs) were recorded prior to and after exposure to 250 microM of the NO donor diethyleneamine/nitric oxide adduct (DETA-NO). Exposure to DETA-NO resulted in increased sIPSCs and mIPSCs frequency, indicating that neurotoxic concentrations of NO enhance GABAergic synaptic transmission in cultured hippocampal neurons. Because GABA synapses appear to be excitatory in the immature brain, this effect may contribute to overall enhanced synaptic transmission and hyperexcitability. We speculate that NO represents one of the mechanisms by which hypoxia-ischemia increases seizure susceptibility in the immature brain.
Zanelli
Santina
S
Department of Pediatrics, Box 800386, University of Virginia, Charlottesville, VA 22908, USA. sz5d@virginia.edu
Naylor
Martha
M
Kapur
Jaideep
J
D000818:Animals; D002478:Cells, Cultured; D004827:Epilepsy / Q000378:metabolism / Q000503:physiopathology; D006624:Hippocampus / Q000254:growth & development / Q000378:metabolism* / Q000503:physiopathology; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism / Q000503:physiopathology; D007150:Immunohistochemistry; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism* / Q000633:toxicity; D020030:Nitric Oxide Donors / Q000633:toxicity; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats; D013570:Synaptic Membranes / Q000378:metabolism / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D005680:gamma-Aminobutyric Acid; D052248:Nitric Oxide Synthase Type I
Am J Physiol Regul Integr Comp Physiol. 2001 Jun;280(6):R1815-22
11353687
Eur J Pharmacol. 1998 Jan 19;342(1):47-9
9544791
Br J Pharmacol. 2002 Mar;135(5):1079-95
11877313
J Neurosci. 2000 Aug 15;20(16):5899-905
10934236
J Neurosci. 2000 Nov 1;20(21):7922-31
11050112
J Neurosci. 2001 Oct 15;21(20):8154-63
11588188
J Neurochem. 2006 May;97(3):724-36
16606371
Ann Neurol. 1998 Dec;44(6):845-57
9851428
Proc Natl Acad Sci U S A. 2007 Dec 18;104(51):20564-9
18077376
J Comp Neurol. 2002 Jan 28;443(1):43-55
11793346
Science. 1994 Sep 23;265(5180):1883-5
7522345
J Neurophysiol. 2004 Feb;91(2):946-57
14534286
Pediatr Radiol. 2006 Jul;36(7):608-20
16770665
J Neurosci. 2008 Feb 6;28(6):1356-65
18256255
J Neurochem. 1998 Jul;71(1):266-73
9648874
J Neurochem. 2004 Jan;88(1):91-101
14675153
Neuroscience. 1999;92(4):1443-54
10426498
J Neurobiol. 1999 Jun 15;39(4):558-68
10380077
Neurosci Lett. 2004 Sep 30;368(3):254-7
15364406
Brain Res Dev Brain Res. 1998 Aug 8;109(2):281-92
9729431
Eur J Neurosci. 2002 Mar;15(6):962-8
11918655
J Neurophysiol. 2007 Nov;98(5):2501-8
17855591
Nature. 1992 Jun 25;357(6380):686-9
1377360
Eur J Neurosci. 2007 Oct;26(7):1889-94
17868368
Cell. 1993 Dec 31;75(7):1273-86
7505721
Proc Natl Acad Sci U S A. 1996 Dec 24;93(26):15423-8
8986827
Neuroscience. 1991;40(3):599-636
1676492
Int J Dev Neurosci. 2002 Jun-Aug;20(3-5):339-47
12175872
J Neurochem. 2006 May;97(3):800-6
16573650
J Cereb Blood Flow Metab. 1993 May;13(3):355-8
8478395
J Neurophysiol. 1998 Jan;79(1):73-81
9425178
Ment Retard Dev Disabil Res Rev. 2001;7(1):56-64
11241883
Neurology. 2002 Feb 26;58(4):542-8
11865130
Neurosci Lett. 1992 Apr 13;138(1):145-8
1383875
J Comp Neurol. 2004 Oct 25;478(4):405-17
15384067
Brain Res Dev Brain Res. 1990 Nov 1;56(2):257-62
2175682
Pediatr Neurol. 2003 Nov;29(5):381-90
14684233
J Neurosci. 2007 Jul 25;27(30):8101-11
17652601
Hippocampus. 1994 Oct;4(5):530-45
7889124
Pediatr Neurol. 2005 Jul;33(1):1-11
15993318
Neurochem Res. 2006 Nov;31(11):1317-25
17053971
Epilepsy Res. 1996 Dec;26(1):131-40
8985695
Eur J Neurosci. 2008 Jun;27(11):2783-802
18588525
Adv Pharmacol. 1995;34:71-90
8562454
Mol Cell Neurosci. 2003 Dec;24(4):1151-69
14697675
Curr Opin Pediatr. 2006 Dec;18(6):628-33
17099361
Mol Pharmacol. 2005 Mar;67(3):775-88
15613639
Brain Res Dev Brain Res. 2000 Oct 28;123(2):119-27
11042340
Neurology. 1999 Nov 10;53(8):1754-61
10563624
J Neurochem. 2006 Jun;97(6):1676-89
16805776
J Neurosci Res. 1993 Jun 1;35(2):192-8
8100588
J Neurosci. 1996 Jan;16(1):418-24
8613807
J Physiol. 2005 Aug 1;566(Pt 3):849-63
15919714
Brain Dev. 2001 Aug;23(5):349-54
11504607
J Pharmacol Sci. 2006;100(5):538-44
16682789
Nature. 1999 Jan 21;397(6716):251-5
9930699
J Comp Neurol. 2006 Apr 10;495(5):497-510
16498682
J Mol Histol. 2004 Nov;35(8-9):765-70
15609089
Neurochem Res. 2000 Dec;25(12):1559-65
11152385
J Cell Mol Med. 2003 Oct-Dec;7(4):401-7
14754508
Prog Brain Res. 1990;83:313-21
2168059
Mol Neurobiol. 2003 Apr;27(2):107-20
12777682
Mol Pharmacol. 2003 Aug;64(2):521-32
12869658
Brain Res. 1998 Mar 16;787(1):117-22
9518575