Modulation Of Neuronal Channels and Receptors in the Brain

大脑神经元通道和受体的调节

• 批准号: 9550096
• 负责人: JERREL L YAKEL
• 金额: $ 243.59万
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/9550096
• 关键词: Acetylcholine; Acute; Address; Agonist; Alzheimer' s Disease; Amygdaloid structure; Animals; Area; Back; Binding; Binding Sites; Biophysics; Biosensor; Brain; Brain Injuries; Brain region; Calcium; Cells; Chelating Agents; Choline; Chronic; Cognition Disorders; Cognitive; Cognitive deficits; Communication; Corpus striatum structure; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Data; Development; Diffuse; Disinhibition; Dopamine; Electrophysiology (science); Epilepsy; Exposure to; Fiber; Fluorescence Resonance Energy Transfer; Functional disorder; Galanin; Gated Ion Channel; Generations; Glutamates; Hippocampus (Brain); Human; Hypertrophy; Impaired cognition; Impairment; In Vitro; Insecticides; Interneurons; Ion Channel Gating; Lead; Learning; Ligands; Light; Link; Location; Maps; Measures; Medial; Mediating; Memory; Modeling; Molecular; Muscarinic Acetylcholine Receptor; Mutation; Nature; Nervous system structure; Neurodegenerative Disorders; Neurons; Neuropeptides; Nicotine; Nicotinic Receptors; Parkinson Disease; Patients; Periodicity; Phosphorylation; Physiological; Physiological Processes; Play; Postsynaptic Membrane; Pregnant Women; Presynaptic Terminals; Rattus; Regulation; Reporting; Research; Reverse Transcriptase Polymerase Chain Reaction; Role; Rotenone; Schizophrenia; Signal Pathway; Signal Transduction; Site; Slice; Small Interfering RNA; Smoke; Substantia nigra structure; Symptoms; Synapses; Synapsins; Synaptic Cleft; Synaptic Transmission; System; Techniques; Tetrodotoxin; Therapeutic; Theta Rhythm; Tobacco Dependence; Work; amyloid peptide; basal forebrain; base; cholinergic; cholinergic neuron; cognitive development; cognitive process; disorder risk; dopaminergic neuron; entorhinal cortex; environmental agent; gamma-Aminobutyric Acid; improved; in utero; inhibitor/antagonist; live cell imaging; mind control; motor disorder; neurotransmitter release; optogenetics; overexpression; patch clamp; positive allosteric modulator; prevent; receptor; therapeutic development; therapy development; voltage clamp

There have been several major accomplishments within the past fiscal year. The activation of 7 nAChRs has been shown to improve hippocampal-dependent learning and memory. However, the molecular mechanism of 7 nAChRs' action remains elusive. We previously reported that activation of 7 nAChRs induced a prolonged enhancement of glutamatergic synaptic transmission in a PKA-dependent manner. Here, we investigated any connection between the activation of the 7 nAChR and cAMP signaling in hippocampal neurons. To address this question, we employed a FRET-based biosensor to measure the intracellular cAMP levels directly via live cell imaging. We found that application of the 7 nAChR-selective agonist choline, in the presence of the 7 nAChR positive allosteric modulator PNU-120596, induced a significant change in emission ratio of F535/F470, which indicated an increase in intracellular cAMP levels. This choline-induced increase was abolished by the 7 nAChR antagonist MLA and the calcium chelator BAPTA, suggesting that the cAMP increase depends on the 7 nAChR activation and subsequent intracellular calcium rise. The selective AC1 inhibitor CB-6673567 and siRNA-mediated deletion of AC1 both blocked the choline-induced cAMP increase, suggesting that calcium-dependent AC1 is required for choline's action. Furthermore, 7 nAChR activation stimulated the phosphorylation of synapsin, which serves as a downstream effector to regulate neurotransmitter release. Our findings provide the first direct evidence to link activation of 7 nAChRs to a cAMP rise via AC1, which defines a new signaling pathway employed by 7 nAChRs. Our study sheds light into potential molecular mechanisms of the positive cognitive actions of 7 nAChR agonists and development of therapeutic treatments for cognitive impairments. Second, the hippocampal theta rhythm emerges as rhythmic and synchronized activities among the hippocampus and hippocampus-associated brain regions during active exploration, providing a potential means for inter-regional communication. However, after decades of research, the origins of the theta rhythm remain elusive, at least partly due to the difficulty in recording from all three essential regions for theta generation, namely the hippocampus itself, the septum, and the entorhinal cortex. For this reason, we established an in vitro theta model in a septo-entorhinal-hippocampal brain slice tri-culture system by pairing septal cholinergic inputs with hippocampal local activities. Our study shows that the local entorhinal cortical circuit may play an active and critical role in hippocampal theta rhythm generation. Our study also reveals a potential mechanism for theta rhythms to emerge as the functional results of dynamic interactions among the septum, hippocampus, and the entorhinal cortex, in the absence of clear pace makers. Lastly, the basal forebrain (BF) is an important regulator of hippocampal and cortical activity. In Alzheimer's disease (AD), there is a significant loss and dysfunction of cholinergic neurons within the BF, and also a hypertrophy of fibers containing the neuropeptide galanin. Understanding how galanin interacts with BF circuitry is critical in determining what role galanin overexpression plays in the progression of AD. Here, we examined the location and function of galanin in the medial septum/diagonal band (MS/DBB) region of the BF. We show that galanin fibers are located throughout the MS/DBB and intermingled with both cholinergic and GABAergic neurons. Whole-cell patch clamp recordings from MS/DBB neurons in acute slices reveal that galanin decreases tetrodotoxin-sensitive spontaneous GABA release and dampens muscarinic receptor-mediated increases in GABA release in the MS/DBB. These effects are not blocked by pre-exposure to -amyloid peptide (A1-42). Optogenetic activation of cholinergic neurons in the MS/DBB increases GABA release back onto cholinergic neurons, forming a functional circuit within the MS/DBB. Galanin disrupts this cholinergic-GABAergic circuit by blocking the cholinergic-induced increase in GABA release. These data suggest that galanin works in the BF to reduce inhibitory input onto cholinergic neurons and to prevent cholinergic-induced increase in inhibitory tone. This disinhibition of cholinergic neurons could serve as a compensatory mechanism to counteract the loss of cholinergic signaling that occurs during the progression of AD.

上一财年取得了几项重大成就。 7 个 nAChR 的激活已被证明可以改善海马依赖性学习和记忆。然而，7 个 nAChR 作用的分子机制仍不清楚。我们之前报道过，7 个 nAChR 的激活以 PKA 依赖性方式诱导谷氨酸能突触传递的长期增强。在这里，我们研究了海马神经元中 7 nAChR 激活和 cAMP 信号传导之间的联系。为了解决这个问题，我们采用基于 FRET 的生物传感器通过活细胞成像直接测量细胞内 cAMP 水平。我们发现，在 7 nAChR 正变构调节剂 PNU-120596 存在的情况下，应用 7 nAChR 选择性激动剂胆碱会引起 F535/F470 发射比的显着变化，这表明细胞内 cAMP 水平增加。这种胆碱诱导的增加被 7 nAChR 拮抗剂 MLA 和钙螯合剂 BAPTA 消除，表明 cAMP 增加取决于 7 nAChR 激活和随后的细胞内钙升高。选择性 AC1 抑制剂 CB-6673567 和 siRNA 介导的 AC1 缺失均能阻断胆碱诱导的 cAMP 增加，表明钙依赖性 AC1 是胆碱作用所必需的。此外，7 nAChR 激活刺激突触蛋白的磷酸化，突触蛋白作为调节神经递质释放的下游效应器。我们的研究结果提供了第一个直接证据，将 7 个 nAChR 的激活与通过 AC1 的 cAMP 升高联系起来，这定义了 7 个 nAChR 所采用的新信号传导途径。我们的研究揭示了 7 种 nAChR 激动剂积极认知作用的潜在分子机制以及认知障碍治疗方法的开发。 其次，海马θ节律在主动探索过程中作为海马和海马相关大脑区域之间有节奏和同步的活动而出现，为区域间交流提供了潜在的手段。然而，经过数十年的研究，theta 节律的起源仍然难以捉摸，至少部分原因是难以记录 theta 产生的所有三个重要区域，即海马体本身、隔膜和内嗅皮层。为此，我们通过将间隔胆碱能输入与海马局部活动配对，在间隔-内嗅-海马脑切片三培养系统中建立了体外 theta 模型。我们的研究表明，局部内嗅皮质回路可能在海马θ节律的产生中发挥积极和关键的作用。我们的研究还揭示了在缺乏明确起搏器的情况下，θ节律作为隔膜、海马和内嗅皮层之间动态相互作用的功能结果而出现的潜在机制。 最后，基底前脑（BF）是海马和皮质活动的重要调节器。在阿尔茨海默病 (AD) 中，BF 内的胆碱能神经元显着丧失和功能障碍，并且含有神经肽甘丙肽的纤维肥大。了解甘丙肽如何与 BF 电路相互作用对于确定甘丙肽过度表达在 AD 进展中所起的作用至关重要。在这里，我们检查了甘丙肽在 BF 内侧隔膜/对角带 (MS/DBB) 区域的位置和功能。我们发现甘丙肽纤维遍布整个 MS/DBB，并与胆碱能和 GABA 能神经元混合。急性切片中 MS/DBB 神经元的全细胞膜片钳记录表明，甘丙肽可减少河豚毒素敏感的自发 GABA 释放，并抑制 MS/DBB 中毒蕈碱受体介导的 GABA 释放增加。这些作用不会因预先暴露于β-淀粉样肽(A1-42)而被阻断。 MS/DBB 中胆碱能神经元的光遗传学激活会增加 GABA 释放回胆碱能神经元，从而在 MS/DBB 内形成功能回路。甘丙肽通过阻断胆碱能诱导的 GABA 释放增加来破坏这种胆碱能-GABA 能回路。这些数据表明，甘丙肽在 BF 中发挥作用，减少对胆碱能神经元的抑制输入，并防止胆碱能诱导的抑制音调增加。这种胆碱能神经元的去抑制可以作为一种补偿机制，以抵消 AD 进展过程中发生的胆碱能信号丧失。