Department of Psychology and Neuroscience Program, University of Michigan, Ann Arbor, Michigan 48109-1043, USA.
J Neurosci. 2010 Mar 3;30(9):3518-30. doi: 10.1523/JNEUROSCI.5712-09.2010.
One-second-long increases in prefrontal cholinergic activity ("transients") were demonstrated previously to be necessary for the incorporation of cues into ongoing cognitive processes ("cue detection"). Nicotine and, more robustly, selective agonists at alpha4beta2* nicotinic acetylcholine receptors (nAChRs) enhance cue detection and attentional performance by augmenting prefrontal cholinergic activity. The present experiments determined the role of beta2-containing and alpha7 nAChRs in the generation of prefrontal cholinergic and glutamatergic transients in vivo. Transients were evoked by nicotine, the alpha4beta2* nAChR agonist ABT-089 [2-methyl-3-(2-(S)-pyrrolindinylmethoxy) pyridine dihydrochloride], or the alpha7 nAChR agonist A-582941 [2-methyl-5-(6-phenyl-pyridazin-3-yl)-octahydro-pyrrolo[3,4-c]pyrrole]. Transients were recorded in mice lacking beta2 or alpha7 nAChRs and in rats after removal of thalamic glutamatergic or midbrain dopaminergic inputs to prefrontal cortex. The main results indicate that stimulation of alpha4beta2* nAChRs evokes glutamate release and that the presence of thalamic afferents is necessary for the generation of cholinergic transients. ABT-089-evoked transients were completely abolished in mice lacking beta2* nAChRs. The amplitude, but not the decay rate, of nicotine-evoked transients was reduced by beta2* knock-out. Conversely, in mice lacking the alpha7 nAChR, the decay rate, but not the amplitude, of nicotine-evoked cholinergic and glutamatergic transients was attenuated. Substantiating the role of alpha7 nAChR in controlling the duration of release events, stimulation of alpha7 nAChR produced cholinergic transients that lasted 10- to 15-fold longer than those evoked by nicotine. alpha7 nAChR-evoked cholinergic transients are mediated in part by dopaminergic activity. Prefrontal alpha4beta2* nAChRs play a key role in evoking and facilitating the transient glutamatergic-cholinergic interactions that are necessary for cue detection and attentional performance.
一秒钟的前额叶胆碱能活动增加(“瞬变”)之前被证明是将线索整合到正在进行的认知过程中(“线索检测”)所必需的。尼古丁和更有效的α4β2烟碱型乙酰胆碱受体(nAChR)选择性激动剂通过增强前额叶胆碱能活性增强线索检测和注意力表现。本实验确定了β2 包含和α7 nAChR 在体内产生前额叶胆碱能和谷氨酸能瞬变中的作用。瞬变由尼古丁、α4β2 nAChR 激动剂 ABT-089 [2-甲基-3-(2-(S)-吡咯烷二氧基)吡啶二盐酸盐]或α7 nAChR 激动剂 A-582941 [2-甲基-5-(6-苯基-哒嗪-3-基)-八氢-吡咯[3,4-c]吡咯]诱发。在缺乏β2 或α7 nAChR 的小鼠和去除丘脑谷氨酸能或中脑多巴胺能传入到前额叶皮质的大鼠中记录瞬变。主要结果表明,α4β2* nAChR 的刺激会引发谷氨酸释放,并且丘脑传入是产生胆碱能瞬变所必需的。在缺乏β2* nAChR 的小鼠中,ABT-089 诱发的瞬变完全被消除。尼古丁诱发的瞬变的幅度,但不是衰减率,在β2敲除小鼠中降低。相反,在缺乏α7 nAChR 的小鼠中,尼古丁诱发的胆碱能和谷氨酸能瞬变的衰减率,但不是幅度,被减弱。证实了α7 nAChR 在控制释放事件持续时间中的作用,刺激α7 nAChR 产生的胆碱能瞬变持续时间比尼古丁诱发的瞬变长 10 到 15 倍。α7 nAChR 诱发的胆碱能瞬变部分由多巴胺能活动介导。前额叶α4β2 nAChR 在引发和促进检测和注意力表现所必需的瞬态谷氨酸-胆碱能相互作用中起着关键作用。