Distinct roles for glycine and GABA in shaping the response properties of neurons in the superior paraolivary nucleus of the rat
Distinct roles for glycine and GABA in shaping the response properties of neurons in the superior paraolivary nucleus of the rat
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DOI：
10.1152/jn.00613.2006
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发表时间：
2007-02-01
影响因子：
2.5
通讯作者：
Berrebi, Albert S.
中科院分区：
文献类型：
--
作者：
Kulesza, Randy J., Jr.;Kadner, Alexander;Berrebi, Albert S.
上级橄榄旁核（SPON）是上级橄榄复合体中的一个重要的橄榄周细胞群。SPON神经元使用γ-氨基丁酸（GABA）作为它们的神经递质，并且被大量的甘氨酸能和GABA能点状分布接触，分别代表来自斜方体内侧核（MNTB）和来自SPON轴突的侧支的密集抑制性神经支配。SPON神经元的自发活动率较低，优先对纯音的偏移做出反应，并对调幅音进行锁相。为了确定甘氨酸和GABA在形成SPON反应中的作用，我们记录了在麻醉大鼠的SPON中的单个单位之前，期间和之后应用甘氨酸受体拮抗剂士的宁，GABA A受体拮抗剂荷包牡丹碱，或同时应用这两种药物。士的宁引起的刺激呈现过程中的尖峰计数的主要增加，随后由偏移尖峰消失。在一半的记录单位，荷包牡丹碱引起适度增加发射过程中的刺激。然而，在86%的单位荷包牡丹碱也引起了大幅度增加的偏移响应。应用药物鸡尾酒引起自发活动增加，刺激呈现过程中的尖峰计数显著增加，并消除了大多数单位的偏移反应。我们得出结论，甘氨酸能抑制MNTB抑制SPON尖峰在声音刺激，是必不可少的产生偏移响应。GABA能抑制，可能来自内在SPON侧支，起着微妙的作用，在一些细胞中有助于抑制刺激期间的放电，在大多数细胞中有助于限制刺激抵消后的放电。
The superior paraolivary nucleus (SPON) is a prominent periolivary cell group of the superior olivary complex. SPON neurons use gamma-aminobutyric acid ( GABA) as their neurotransmitter and are contacted by large numbers of glycinergic and GABAergic punctate profiles, representing a dense inhibitory innervation from the medial nucleus of the trapezoid body (MNTB) and from collaterals of SPON axons, respectively. SPON neurons have low rates of spontaneous activity, respond preferentially to the offset of pure tones, and phase-lock to amplitude-modulated tones. To determine the roles of glycine and GABA in shaping SPON responses, we recorded from single units in the SPON of anesthetized rats before, during, and after application of the glycine receptor antagonist strychnine, the GABA A receptor antagonist bicuculline, or both drugs applied simultaneously. Strychnine caused a major increase in spike counts during the stimulus presentation, followed by the disappearance of offset spikes. In half of the recorded units, bicuculline caused moderately increased firing during the stimulus. However, in 86% of units bicuculline also caused a large increase in the magnitude of the offset response. Application of the drug cocktail caused increased spontaneous activity, dramatically increased spike counts during the stimulus presentation, and eliminated the offset response in most units. We conclude that glycinergic inhibition from the MNTB suppresses SPON spiking during sound stimulation and is essential in generating offset responses. GABAergic inhibition, presumably from intrinsic SPON collaterals, plays a subtler role, contributing in some cells to suppression of firing during the stimulus and in most cells to restrict firing after stimulus offset.