Oxytocinergic input to the sympathetic preganglionic neurons in the rat. A light and electron microscopic study using immunocytochemical technique.

用霍乱毒素B亚单位(CTB)或辣根过氧化物酶标记的CTB逆行标记脊髓内的交感节前神经元(SPN)，用逆行胞体标记和免疫组织化学相结合的方法研究催产素能纤维与交感节前神经元的联系。催产素免疫反应纤维位于中间带，包括交感神经节前亚核。在中央自主神经核和间质核内，常可见棕染的催产素阳性突起或终末，以标记黑染的SPN树突。电子显微镜观察显示，催产素免疫反应终末与交感节前神经元的树突或胞体形成突触。终末含有许多透明的小圆形小泡和少数大的核心小泡。这些结果清楚地表明SPN的很大一部分是由含有催产素的纤维支配的。对这些纤维的来源进行了讨论，认为它们可能是来自下丘脑室旁核的下行纤维。

A combination of retrograde cell body labeling and immunohistochemistry was employed to elucidate how oxytocinergic fibers make contact with sympathetic preganglionic neurons (SPNs) in the rat spinal cord from T_1 to T_4. SPNs were labeled retrogradely using cholera toxin subunit B (CTb) or horseradish peroxidase conjugated CTb. Oxytocin immunoreactive (ir) fibers were found in the intermediate zone including the sympathetic preganglionic subnuclei. In the central autonomic nucleus and the intercalated nucleus, brown-stained oxytocin-ir varicosities or terminals were frequently observed to stud black-stained dendrites of SPNs. Electron microscopical observations showed that oxytocin-ir terminals form synapses with dendrites or soma of the sympathetic preganglionic neurons. The terminals contained numerous small clear round vesicles and a few large cored vesicles. These results clearly show that a large part of SPNs is innervated by oxytocin containing fibers. The origin of these fibers is discussed, and it is concluded that they are probably descending fibers from the paraventricular nucleus of the hypothalamus.