Optimal attention performance requires cholinergic modulation of corticothalamic neurons in the prefrontal cortex. These pyramidal cells express specialized nicotinic acetylcholine receptors containing the α5 subunit encoded by Chrna5. Disruption of this gene impairs attention, but the advantage α5 confers on endogenous cholinergic signaling is unknown. To ascertain this underlying mechanism, we used optogenetics to stimulate cholinergic afferents in prefrontal cortex brain slices from compound-transgenic wild-type and Chrna5 knock-out mice of both sexes. These electrophysiological experiments identify that Chrna5 is critical for the rapid onset of the postsynaptic cholinergic response. Loss of α5 slows cholinergic excitation and delays its peak, and these effects are observed in two different optogenetic mouse lines. Disruption of Chrna5 does not otherwise perturb the magnitude of the response, which remains strongly mediated by nicotinic receptors and tightly controlled by autoinhibition via muscarinic M2 receptors. However, when conditions are altered to promote sustained cholinergic receptor stimulation, it becomes evident that α5 also works to protect nicotinic responses against desensitization. Rescuing Chrna5 disruption thus presents the double challenge of improving the onset of nicotinic signaling without triggering desensitization. Here, we identify that an agonist for the unorthodox α-α nicotinic binding site can allosterically enhance the cholinergic pathway considered vital for attention. Treatment with NS9283 restores the rapid onset of the postsynaptic cholinergic response without triggering desensitization. Together, this work demonstrates the advantages of speed and resilience that Chrna5 confers on endogenous cholinergic signaling, defining a critical window of interest for cue detection and attentional processing.

SIGNIFICANCE STATEMENT The α5 nicotinic receptor subunit (Chrna5) is important for attention, but its advantage in detecting endogenous cholinergic signals is unknown. Here, we show that α5 subunits permit rapid cholinergic responses in prefrontal cortex and protect these responses from desensitization. Our findings clarify why Chrna5 is required for optimal attentional performance under demanding conditions. To treat the deficit arising from Chrna5 disruption without triggering desensitization, we enhanced nicotinic receptor affinity using NS9283 stimulation at the unorthodox α-α nicotinic binding site. This approach successfully restored the rapid-onset kinetics of endogenous cholinergic neurotransmission. In summary, we reveal a previously unknown role of Chrna5 as well as an effective approach to compensate for genetic disruption and permit fast cholinergic excitation of prefrontal attention circuits.

最佳的注意力表现需要前额叶皮层中的皮层丘脑神经元的胆碱能调节。这些锥体细胞表达含有Chrna5编码的α5亚基的专门的烟碱型乙酰胆碱受体。该基因的破坏削弱了注意力，但α5赋予内源胆碱能信号的优势尚不清楚。为了确定这种潜在机制，我们使用光遗传学来刺激来自复合转基因野生型和Chrna5敲除小鼠的前额叶皮层脑切片中的胆碱能传入。这些电生理实验确定Chrna5对于突触后胆碱能反应的快速发作至关重要。α5的丢失减慢了胆碱能的激发并延迟了其峰值，并且在两种不同的光遗传学小鼠品系中观察到了这些作用。Chrna5的破坏不会以其他方式干扰反应的程度，该反应的程度仍然由烟碱受体强烈介导，并通过毒蕈碱M2受体的自抑制作用受到严格控制。然而，当改变条件以促进持续的胆碱能受体刺激时，很明显α5也起着保护烟碱反应免于脱敏的作用。救援CHRNA5因此，破坏存在双重挑战，即在不触发脱敏的情况下改善烟碱信号的发生。在这里，我们确定了非正统的α-α烟碱结合位点的激动剂可以变构地增强被认为至关重要的胆碱能途径。NS9283的治疗可恢复突触后胆碱能反应的快速发作，而不会引起脱敏。在一起，这项工作证明了Chrna5赋予内源胆碱能信号传递的速度和弹性的优势，为线索检测和注意处理定义了一个重要的关注窗口。

意义声明α5烟碱样受体亚基（Chrna5）对于引起注意很重要，但在检测内源胆碱能信号方面的优势尚不清楚。在这里，我们显示α5亚基允许前额叶皮层中快速的胆碱能反应，并保护这些反应免于脱敏。我们的发现阐明了为什么在要求苛刻的条件下，Chrna5才能获得最佳注意力表现。治疗Chrna5引起的赤字在不触发脱敏的情况下，我们通过在非正统的α-α烟碱结合位点使用NS9283刺激增强了烟碱受体的亲和力。这种方法成功地恢复了内源胆碱能神经传递的快速发作动力学。总而言之，我们揭示了Chrna5以前未知的作用以及一种有效的方法来补偿基因破坏并允许前额叶注意回路的快速胆碱能激发。