Burstein R, Cliffer K D, Giesler G J
Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455.
J Comp Neurol. 1990 Jan 15;291(3):329-44. doi: 10.1002/cne.902910302.
We recently demonstrated that large numbers of neurons in the spinal cord of rats project directly to the hypothalamus. In the present study, we used the retrograde tracer Fluoro-Gold (FG) to examine this projection more completely. In the first series of studies, we attempted to label the entire population of spinal cord neurons that project to the hypothalamus. Injections that virtually filled the hypothalamus on one side without spreading into any other diencephalic area labeled a large number of neurons (estimated to be more than 9,000 in the case with the most neurons labeled) bilaterally at all levels of the spinal cord. Approximately 60% of the labeled neurons were contralateral to the injection. The greatest number of labeled neurons was found within the deep dorsal horn. Many were also found within the lateral spinal nucleus, the superficial dorsal horn, and the gray matter surrounding the central canal. A small number of labeled cells was located in the intermediate zone and ventral horn of the spinal gray matter. Labeled neurons were distributed bilaterally within the sacral parasympathetic nucleus and trigeminal nucleus caudalis. Injections of FG restricted to the medial hypothalamus labeled neurons within the spinal cord in a distribution similar to that produced by injections that filled the hypothalamus. However, fewer neurons were labeled in the spinal cord (estimated to be more than 6,200) and trigeminal nucleus caudalis. Injections of FG restricted to the lateral hypothalamus also labeled fewer neurons (approximately 3,300) than did injections that filled the hypothalamus. In these cases, also, the pattern of labeled neurons within the spinal cord was similar to that produced by injections within either medial or both medial and lateral hypothalamus. However, few neurons were labeled in the sacral parasympathetic nucleus following injections into the lateral hypothalamus. These findings show the distribution of a large number of spinal cord neurons that project directly to medial or lateral hypothalamic regions that are involved in autonomic, neuroendocrine, and emotional responses to somatosensory stimulation, including painful stimuli.
我们最近证实，大鼠脊髓中的大量神经元可直接投射至下丘脑。在本研究中，我们使用逆行示踪剂荧光金（FG）更全面地研究这一投射。在第一组研究中，我们试图标记投射至下丘脑的整个脊髓神经元群体。在一侧几乎填满下丘脑而未扩散至任何其他间脑区域的注射，在脊髓的所有节段双侧标记了大量神经元（在标记神经元最多的情况下估计超过9000个）。约60%的标记神经元位于注射对侧。标记神经元数量最多的位于深背角。在外侧脊髓核、浅背角和中央管周围的灰质中也发现了许多标记神经元。少量标记细胞位于脊髓灰质的中间带和腹角。标记神经元双侧分布于骶副交感核和三叉神经尾侧核。将FG注射局限于下丘脑内侧时，脊髓内标记的神经元分布与填满下丘脑的注射所产生的分布相似。然而，脊髓（估计超过6200个）和三叉神经尾侧核中标记的神经元较少。将FG注射局限于下丘脑外侧时，标记的神经元也比填满下丘脑的注射少（约3300个）。在这些情况下，脊髓内标记神经元的模式也与在下丘脑内侧或内侧和外侧注射所产生的模式相似。然而，向下丘脑外侧注射后，骶副交感核中标记的神经元很少。这些发现显示了大量直接投射至下丘脑内侧或外侧区域的脊髓神经元的分布，这些区域参与对躯体感觉刺激（包括疼痛刺激）的自主、神经内分泌和情感反应。
