Broussard D L, Lynn R B, Wiedner E B, Altschuler S M
Division of Gastroenterology and Nutrition, Children's Hospital of Philadelphia, Pennsylvania, USA.
Gastroenterology. 1998 Jun;114(6):1268-75. doi: 10.1016/s0016-5085(98)70433-0.
BACKGROUND & AIMS: The buccopharyngeal and esophageal phases of swallowing are controlled by distinct networks of premotor neurons localized in the nucleus tractus solitarius. The neuronal circuitry coordinating the two phases was investigated using a combination of central and peripheral tracing techniques.
Using pseudorabies virus, a transsynaptic tracer, in anesthetized rats, third-order esophageal neurons (neurons projecting to premotor neurons) were identified. In a separate protocol that combined transsynaptic and retrograde fluorescent tracing, third-order esophageal neurons projecting to pharyngeal motoneurons (buccopharyngeal premotor neurons) were then identified.
Third-order esophageal neurons were identified in the interstitial and intermediate subnuclei of the nucleus tractus solitarius and in other medullary, pontine, midbrain, and forebrain nuclei. A subpopulation of these neurons (double labeled) in the interstitial and intermediate subnuclei were found to project to pharyngeal motoneurons (buccopharyngeal premotor neurons) and to be linked synaptically to esophageal premotor neurons.
The synaptic link between buccopharyngeal and esophageal premotor neurons provides an anatomic pathway for the central initiation of esophageal peristalsis and its coordination with the pharyngeal phase of swallowing. This neural circuitry within the nucleus tractus solitarius is consistent with a complex central control mechanism for the swallowing motor sequence that can function independently of afferent feedback.
吞咽的口咽期和食管期由位于孤束核的不同运动前神经元网络控制。使用中枢和外周追踪技术相结合的方法，研究了协调这两个阶段的神经回路。
在麻醉大鼠中使用伪狂犬病病毒（一种跨突触示踪剂）来识别三级食管神经元（投射到运动前神经元的神经元）。在另一个结合了跨突触和逆行荧光追踪的实验方案中，随后识别出投射到咽运动神经元（口咽运动前神经元）的三级食管神经元。
在孤束核的中间和中间亚核以及其他延髓、脑桥、中脑和前脑核中识别出三级食管神经元。发现这些位于中间和中间亚核的神经元亚群（双重标记）投射到咽运动神经元（口咽运动前神经元），并与食管运动前神经元形成突触连接。
口咽和食管运动前神经元之间的突触连接为食管蠕动的中枢启动及其与吞咽咽期的协调提供了解剖学途径。孤束核内的这种神经回路与吞咽运动序列的复杂中枢控制机制一致，该机制可独立于传入反馈发挥作用。
