Regulation of the activity of hippocampal stratum oriens interneurons by α7 nicotinic acetylcholine receptors

被引:45
作者
Buhler, AV
Dunwiddie, TV
机构
[1] Dept Vet Affairs, Med Res Serv, Denver, CO USA
[2] Univ Colorado, Hlth Sci Ctr, Neurosci Program, Denver, CO USA
[3] Univ Colorado, Hlth Sci Ctr, Dept Pharmacol, Denver, CO 80262 USA
关键词
alpha-bungarotoxin; GABA; acetylcholinesterase; theta rhythm; desensitization; synaptic;
D O I
10.1016/S0306-4522(01)00257-3
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
GABAergic interneurons have been shown to be a major target of cholinergic inputs to the hippocampus. Because these interneurons project to pyramidal neurons as well as other interneurons, activation of the cholinergic system is likely to produce a complex modulation of local inhibitory activity. To better understand the role of postsynaptic alpha7 nicotinic acetylcholine receptors in the hippocampus, we have characterized the effects of nicotinic agents on local interneurons of the rat CAI stratum oriens in terms of activation, desensitization, and region of axonal termination. Fast application of acetylcholine onto stratum oriens interneurons during whole-cell recordings from hippocampal slices activated the majority of cells tested, and these responses were mediated almost entirely by alpha7 nicotinic acetylcholine receptors. Anatomical reconstructions showed no clear relationship between the acetylcholine responsivity of interneurons and the regions to which their axons project. Currents mediated by a7 receptors declined markedly during repetitive activation in the theta rhythm range (4-12 Hz) when activated by either pressure application or synaptic release of acetylcholine. However, the decay of alpha7 receptor-mediated currents was unaffected by treatment with the cholinesterase, inhibitor neostigmine (10 nM-10 muM), suggesting that hydrolysis of acetylcholine is not a rate-limiting step in the termination of these responses. From these findings we suggest that nicotinic receptor activity in this region has an extensive and complex impact on local inhibitory circuits that is mediated by activation of several classes of intrinsic GABAergic cells. In addition, desensitization of the a7 nicotinic acetylcholine receptor is likely to contribute to the decay of individual responses to pressure application of agonist, and may also act in a cumulative fashion to impair the ability of these receptors to support repetitive activity during trains of activation. If applicable to alpha7 receptor responses in vivo, we suggest it may be difficult to enhance these responses for therapeutic purposes with cholinesterase inhibitors. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserved.
引用
收藏
页码:55 / 67
页数:13
相关论文
共 52 条
[1]   NICOTINIC RECEPTOR FUNCTION IN THE MAMMALIAN CENTRAL-NERVOUS-SYSTEM [J].
ALBUQUERQUE, EX ;
PEREIRA, EFR ;
CASTRO, NG ;
ALKONDON, M ;
REINHARDT, S ;
SCHRODER, H ;
MAELICKE, A .
DIVERSITY OF INTERACTING RECEPTORS, 1995, 757 :48-72
[2]   Choline is a selective agonist of α7 nicotnic acetylcholine receptors in the rat brain neurons [J].
Alkondon, M ;
Pereira, EFR ;
Cortes, WS ;
Maelicke, A ;
Albuquerque, EX .
EUROPEAN JOURNAL OF NEUROSCIENCE, 1997, 9 (12) :2734-2742
[3]  
Alkondon M, 1999, J NEUROSCI, V19, P2693
[4]   α-Bungarotoxin- and methyllycaconitine-sensitive nicotinic receptors mediate fast synaptic transmission in interneurons of rat hippocampal slices [J].
Alkondon, M ;
Pereira, EFR ;
Albuquerque, EX .
BRAIN RESEARCH, 1998, 810 (1-2) :257-263
[5]  
ALKONDON M, 1993, J PHARMACOL EXP THER, V265, P1455
[6]   Desensitization of mouse nicotinic acetylcholine receptor channels -: A two-gate mechanism [J].
Auerbach, A ;
Akk, G .
JOURNAL OF GENERAL PHYSIOLOGY, 1998, 112 (02) :181-197
[7]   Intracellular recordings from medial septal neurons during hippocampal theta rhythm [J].
Brazhnik, ES ;
Fox, SE .
EXPERIMENTAL BRAIN RESEARCH, 1997, 114 (03) :442-453
[8]  
Buckmaster PS, 1996, HIPPOCAMPUS, V6, P330, DOI 10.1002/(SICI)1098-1063(1996)6:3<330::AID-HIPO9>3.0.CO
[9]  
2-Q
[10]  
BUHLER AV, 2000, SOC NEUR ABSTR, V26, P1914