Dopaminergic Input to the Inferior Colliculus in Mice.
Dopaminergic Input to the Inferior Colliculus in Mice.
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DOI：
10.3389/fnana.2015.00168
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发表时间：
2015
影响因子：
2.9
通讯作者：
Portfors CV
中科院分区：
文献类型：
--
作者：
Nevue AA;Elde CJ;Perkel DJ;Portfors CV
感觉神经元对刺激的反应可以受到多种因素的调节，包括注意力、情绪、行为背景和涉及神经调节系统的疾病。例如，帕金森病（PD）患者的语音处理功能紊乱，这表明多巴胺改变了这些突出声音的正常表达。因此，了解多巴胺调节听觉处理的机制是一个重要的目标。主要的听觉中脑核，下丘（IC），是一个可能的位置多巴胺能调制的听觉处理，因为它包含多巴胺受体和神经末梢的酪氨酸羟化酶（TH），多巴胺合成的限速酶免疫反应。然而，多巴胺能输入到IC的来源是未知的。在这项研究中，我们将一种逆行示踪剂注入小鼠的IC，然后对组织进行TH染色。我们还对多巴胺β-羟化酶（DBH）进行了免疫染色，DBH是一种将多巴胺转化为去甲肾上腺素的关键酶，以区分多巴胺能和去甲肾上腺素能输入。在丘脑束旁核（SPF）中，TH阳性的逆行标记神经元在双侧可见，同侧优势明显。我们在其他脑区观察到的所有逆行标记的神经元都是TH阴性的。使用顺行示踪剂证实了来自SPF的投射，揭示了IC中TH阳性和DBH阴性顺行标记的纤维和终末。虽然这种多巴胺能输入到IC的功能作用尚不清楚，但它为听觉处理的上下文依赖性调制提供了潜在的机制。
The response of sensory neurons to stimuli can be modulated by a variety of factors including attention, emotion, behavioral context, and disorders involving neuromodulatory systems. For example, patients with Parkinson’s disease (PD) have disordered speech processing, suggesting that dopamine alters normal representation of these salient sounds. Understanding the mechanisms by which dopamine modulates auditory processing is thus an important goal. The principal auditory midbrain nucleus, the inferior colliculus (IC), is a likely location for dopaminergic modulation of auditory processing because it contains dopamine receptors and nerve terminals immunoreactive for tyrosine hydroxylase (TH), the rate-limiting enzyme in dopamine synthesis. However, the sources of dopaminergic input to the IC are unknown. In this study, we iontophoretically injected a retrograde tracer into the IC of mice and then stained the tissue for TH. We also immunostained for dopamine beta-hydroxylase (DBH), an enzyme critical for the conversion of dopamine to norepinephrine, to differentiate between dopaminergic and noradrenergic inputs. Retrogradely labeled neurons that were positive for TH were seen bilaterally, with strong ipsilateral dominance, in the subparafascicular thalamic nucleus (SPF). All retrogradely labeled neurons that we observed in other brain regions were TH-negative. Projections from the SPF were confirmed using an anterograde tracer, revealing TH-positive and DBH-negative anterogradely labeled fibers and terminals in the IC. While the functional role of this dopaminergic input to the IC is not yet known, it provides a potential mechanism for context dependent modulation of auditory processing.