Cholinergic responses in crossed tecto-reticular neurons of rat superior colliculus.
Cholinergic responses in crossed tecto-reticular neurons of rat superior colliculus.
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DOI：
10.1152/jn.90723.2008
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发表时间：
2008-11
影响因子：
2.5
通讯作者：
T. Sooksawate;K. Isa;T. Isa
中科院分区：
文献类型：
--
作者：
T. Sooksawate;K. Isa;T. Isa
哺乳动物上级丘（SC）的中间灰质层（SGI）神经元接受来自脑干臂旁区的胆碱能神经支配，该区域似乎调节SC的信号处理。为了阐明其在定向行为中的作用，我们研究了SGI的主要输出神经元群--交叉顶盖网状神经元（cTRNs），通过全细胞膜片钳技术从大鼠（PND 17-22）获得的SC切片中的对侧脑干凝视中心逆行标记来鉴定。氨甲酰胆碱浴浴可诱导1）烟碱内向（nIN）+毒蕈碱内向（mIN）（11/24）或2）nIN + mIN +毒蕈碱外向（mOUT）（13/24）电流反应。瞬时压力应用1 mM乙酰胆碱引起的nIN在所有测试的神经元（n = 58）。在这些神经元中的大多数（52/58），nIN完全抑制二氢-β-erythroidine，α 4 β 2烟碱受体亚型的特异性拮抗剂。其余6/58个神经元不仅表现出较慢的α 4 β 2受体介导的成分，但也有一个更快的成分，抑制了α 7烟碱受体，α-银环蛇毒素的特异性拮抗剂。表达α 7烟碱受体的cTRN往往比缺乏α 7受体的cTRN尺寸更小。浴用毒蕈碱诱导两种反应模式：仅mIN（17/38）和mIN+ mOUT（21/38）。mIN和mOUT分别由M3（加上M1）和M2毒蕈碱受体介导。这些结果表明，胆碱能输入cTRNs的主要反应是兴奋性的。这将表明脑干胆碱能系统在执行定向行为（包括扫视眼球运动）中的促进作用。
Neurons in the intermediate gray layer (SGI) of mammalian superior colliculus (SC) receive cholinergic innervation from the brain stem parabrachial region, which seems to modulate the signal processing in the SC. To clarify its role particularly in orienting behaviors, we studied cholinergic effects on the major output neuron group of the SGI, crossed tecto-reticular neurons (cTRNs), identified by retrograde labeling from the contralateral brain stem gaze center in SC slices obtained from rats (PND 17-22) by whole cell patch-clamp techniques. Bath application of carbachol induced either 1) nicotinic inward (nIN) + muscarinic inward (mIN) (11/24) or 2) nIN + mIN + muscarinic outward (mOUT) (13/24) current responses. Transient pressure application of 1 mM acetylcholine elicited nIN in all neurons tested (n = 58). In a majority of these neurons (52/58), the nIN was completely suppressed by dihydro-beta-erythroidine, a specific antagonist for alpha4beta2 nicotinic receptor subtype. The remaining 6/58 neurons exhibited not only the slower alpha4beta2 receptor-mediated component but also a faster component that was inhibited by a specific antagonist for alpha7 nicotinic receptor, alpha-bungarotoxin. cTRNs expressing alpha7 nicotinic receptors tended to be smaller in size than those lacking alpha7 receptors. Bath application of muscarine induced two response patterns: mIN only (17/38) and mIN+ mOUT (21/38). The mIN and mOUT were mediated by M3 (plus M1) and M2 muscarinic receptors, respectively. These results suggest that a major response to cholinergic inputs to cTRNs is excitatory. This would indicate the facilitatory role of the brain stem cholinergic system in the execution of orienting behaviors including saccadic eye movements.