Different roles for GABA(A) and GABA(B) receptors in visual processing in the rat superior colliculus
Different roles for GABA(A) and GABA(B) receptors in visual processing in the rat superior colliculus
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DOI：
10.1111/j.1469-7793.1997.629bd.x
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发表时间：
1997-11-01
影响因子：
5.5
通讯作者：
Salt, TE
中科院分区：
文献类型：
--
作者：
Binns, KE;Salt, TE
1. 上丘（SGS）的浅灰色层含有高比例的gaba能抑制神经元。我们研究了GABA受体在SGS视觉活动的突触传递中的作用，这可能是由周围抑制和反应习惯等抑制机制驱动的。采用多管玻璃离子电泳移液管记录氨基脲麻醉大鼠SGS单神经元活动。视觉刺激是通过放置在感受野的监视器上的移动的条状和固定的光点来提供的。GABA和GABA(B)激动剂巴氯芬的喷射均能降低对移动杆的反应（刺激间隔大于等于8秒）。GABA(A)拮抗剂双库兰可逆转GABA(A)的作用，而巴氯芬的作用可被GABA(B)拮抗剂CGP 35348.4拮抗。通过绘制对直径增加的闪点的响应来估计环绕抑制。在对照组中，将光斑直径扩大到超过er；刺激感受野引起了反应的减弱。这种抑制环被二胡兰可逆地减少，但CGP 35348没有作用。反应习惯化是在重复刺激呈现过程中视觉反应的逐渐减少。在对照组中，当刺激（移动条）出现5次，刺激间隔为0.5 s时，视觉反应降低到初始水平的44±3%。在CGP 35348喷射过程中，反应习惯化可逆地降低。双库林对反应习惯无影响。双球茎碱对上丘环绕抑制的作用与外膝状核的类似研究一致，表明GABA(A)受体介导了这种作用。GABA(B)受体在视觉系统中的作用研究较少。CGP 35348对反应习惯的降低表明，至少在SGS中，GABA(B)受体在视觉传递中具有不同于GABA(A)受体的重要作用。
1. The superficial grey layer of the superior colliculus (SGS) contains a high proportion of GABAergic inhibitory neurones. We have investigated the role of GABA receptors in synaptic transmission of aspects of visual activity in the SGS that may be driven by inhibitory mechanisms, such as surround inhibition and response habituation.2. Multi-barrel glass iontophoretic pipettes were used to record single neuronal activity in the SGS of urethane-anaesthetized rats. Visual stimulation was provided by the display of moving bars and stationary spots of light on a monitor placed in the receptive field.3. Both ejection of GABA and the GABA(B) agonist baclofen reduced responses to moving bars (interstimulus intervals greater than or equal to 8 s). The effects of GABA were reversed by the GABA(A) antagonist bicuculline, and the effects of baclofen were antagonized by the GABA(B) antagonist CGP 35348.4. Surround inhibition was estimated by plotting the response to flashed spots of increasing diameter. In controls, expanding the spot diameter beyond the er;citatory receptive field caused a decrease in the response. This inhibitory surround was reversibly reduced by bicuculline, but CGP 35348 had no effect.5. Response habituation is the progressive reduction in the visual response during repetitive stimulus presentation. In controls, the visual response was reduced to 44 +/- 3 % of its initial level when a stimulus (moving bar) was presented 5 times with an interstimulus interval of 0.5 s. During CGP 35348 ejection, response habituation was reversibly reduced. Bicuculline had no effect on response habituation.6. The effects of bicuculline on surround inhibition in the superior colliculus are consistent with similar studies in the lateral geniculate nucleus which indicate that GABA(A) receptors mediate this effect. The function of GABA(B) receptors in the visual system is less well researched. The reduction of response habituation with CGP 35348 demonstrates that, at least in the SGS, GABA(B) receptors have an important role in visual transmission which is distinct from that of GABA(A) receptors.