Synaptic processing in the gustatory brainstem

味觉脑干的突触处理

• 批准号: 7006240
• 负责人: Cheng-Shu Li
• 金额: $ 16.44万
• 依托单位: SOUTHERN ILLINOIS UNIVERSITY CARBONDALE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7006240
• 关键词: afferent nerve; brain stem; chemoreceptors; chorda tympani; cranial nerves; electrodes; electrophysiology; endogenous opioid; hamsters; membrane potentials; neural information processing; neural transmission; neurons; neuropeptide receptor; neuropeptides; opioid receptor; potassium channel; single cell analysis; solitary tract nucleus; synapses; taste; taste buds; tissue /cell culture; tongue; voltage /patch clamp

DESCRIPTION (provided by applicant): Inhibitory modulation is an important aspect of taste processing in the nucleus of the solitary tract (NST). Numerous in vivo and in vitro studies have demonstrated gamma-aminobutyric acid (GABA) to be an inhibitory neurotransmitter in taste processing in the NST. Recently, the influence of met-enkaphalin on taste responsive neurons in the rostral NST has been demonstrated in an in vivo model. In the present application the mechanisms through which opioids act as inhibitory neuropeptides in taste information processing in the gustatory NST are investigated. These experiments involve an in vitro brainstem slice preparation in which the activity of NST neurons that have been retrogradely labeled from the taste responsive region of the parabrachial nuclei (PbN) is recorded. These experiments test the hypothesis that both presynaptic and postsynaptic mechanisms are involved in opioid-mediated inhibition of taste activity. Clinical studies show that patients with unilateral gustatory nerve damage often report no subjective change in taste experience. The mechanisms underlying this 'taste constancy' are thought to occur centrally, most likely in the NST. Several investigators have suggested that the loss of taste information from the chorda tympani (CT) nerve is compensated by a release of inhibition on IXth nerve input. However, the possibility of compensation by taste input from the other side of the tongue has never been investigated. The hypotheses in the present application are that NST neurons receive taste information from both the ipsilateral and contralateral sides of the tongue and that the ascending pathway from the contralateral side of the tongue involves glutamatergic projections from the contralateral NST. To address these hypotheses, the PI proposes to use both a whole-animal electrophysiological preparation, within which it is possible to investigate functionally how peripheral gustatory information is carried to the contralateral NST, and an in vitro slice preparation, in which the synaptic mechanisms involved in this bilateral communication can be studied in greater detail. These studies will provide new insights into the mechanisms by which neurons in the first central taste relay are involved in modulating and processing gustatory information.

描述(申请人提供)：抑制性调节是孤束核(NST)味觉处理的一个重要方面。大量的体内和体外研究表明，γ-氨基丁酸(GABA)在NST的味觉加工中是一种抑制性神经递质。最近，在活体模型中证实了甲硫氨酸对吻侧NST中的味觉反应神经元的影响。在目前的应用中，研究了阿片类物质作为抑制性神经肽在味觉NST的味觉信息处理中的作用机制。这些实验涉及体外脑干切片制备，其中记录了从臂旁核(PBN)的味觉响应区逆行标记的NST神经元的活动。这些实验验证了这一假设，即突触前和突触后机制都涉及阿片类药物介导的味觉活动抑制。 临床研究表明，单侧味觉神经受损的患者通常报告味觉体验没有主观变化。这种“味道恒定”背后的机制被认为是集中发生的，最有可能发生在NST。一些研究人员认为，鼓索(CT)神经味觉信息的丧失可以通过释放对IXth神经输入的抑制来补偿。然而，从舌头另一侧输入的味觉进行补偿的可能性从未被研究过。本研究假设NST神经元同时接受同侧和对侧舌的味觉信息，对侧舌的上行通路涉及对侧NST的谷氨酸能投射。为了解决这些假说，PI建议既使用全动物电生理准备，在其中可以从功能上研究外周味觉信息如何被携带到对侧NST，又使用体外切片准备，其中涉及这种双边通信的突触机制可以被更详细地研究。这些研究将为第一中枢味觉中继器中的神经元参与调制和处理味觉信息的机制提供新的见解。