DESCENDING MODULATION OF SPINAL SUBSTANTIA GELATINOSA

许多研究表明，脑干区域，如中缝核 大、中脑导水管周围灰质可控制感觉神经元的流入 信息传递到脊髓。 最近发现， 镇痛作用可能是由刺激这些大脑中枢引起的， 镇痛作用可以通过相同的机制介导。 涉及的途径 这种"下行控制"从脑啡肽的神经元延伸到大脑皮层， 中脑中央灰质，投射到大脑中的多巴胺能神经元。 中缝大核又投射到脊髓边缘 带（MZ）（I层）、胶状质（SG）（II层）和核 固有层（V层）。 然而，许多问题仍然没有答案， 包括：1）中枢神经递质的类型 神经系统（CNS）水平和2）形态和生理 这些下行通路发挥作用的底物。 的 本研究的目的是通过以下研究来探讨这些问题：1） MZ和SG神经元的形态，并确定投射神经元， 通过局灶性脑干刺激调制; 2）突触传导 局灶性脑干刺激引起的变化; 3） 脑干神经元释放的神经递质 传统一体 细胞外和细胞内的记录将用于生理学上的 识别中间神经元和投射神经元。 离子导入 细胞内标记将用于识别记录的神经元， 检查光和EM水平。 微离子导入和加压 注射将用于局部应用特异性拮抗剂至假定的 神经递质，最后，免疫细胞化学结合 将使用解剖示踪剂来建立 下行连接和各种假定的神经递质发现， 脊柱SG。 这些研究的结果应该导致一个基本的 了解中枢神经系统调节躯体感觉的机制 脊柱水平的信息。

Many studies have shown that brain stem regions such as the nucleus raphe magnus and periaqueductal gray can control the inflow of sensory information to the spinal cord. It has recently been found that selective analgesia may result from stimulating these brain centers and that morphine analgesia may be mediated by the same mechanisms. Pathways implicated in this "descending control" extend from enkephalin-containing neurons in the mesencephalic central gray which project to serotonergic neurons in the nucleus raphe magnus, which in turn project to the spinal cord marginal zone (MZ) (lamina I), substantia gelatinosa (SG) (lamina II), and nucleus proprius (lamina V). However, many questions still remain unanswered, including: 1) the types of neurotransmitters involved at the central nervous system (CNS) level and 2) the morphological and physiological substrates by which these descending pathways produce their effects. The aim of this research proposal is to explore these issues by studying: 1) the morphology of MZ and SG neurons and identified projection neurons that are modulated by focal brainstem stimulation; 2) the synaptic conductance changes evoked by focal brainstem stimulation; 3) the types of neurotransmitters released by brainstem neurons. Conventional single unit recordings, both extra and intracellular, will be used to physiologically identify interneurons and projection neurons. Iontophoresis of intracellular labels will be used to identify the recorded neurons for examination at light and EM levels. Microiontophoresis and pressure injection will be used to locally apply specific antagonists to putative neurotransmitters, and finally, immunocytochemistry combined with anatomical tracers will be used to establish the relationship between descending connections and the various putative neurotransmitters found in the spinal SG. The results of these studies should lead to a basic understanding of the mechanisms whereby the CNS can modulate somatosensory information at the spinal level.