大鼠骶髓后连合核的中枢联系及其机能分析——HRP法研究

THE CENTRAL CONNECTIONS AND FUNCTIONAL CONSIDERATIONS OF THE DORSAL COMMISSURAL NUCLEUS OF THE RAT——A HRP METHOD STUDY

分别向大鼠脊髓L_6、S_1后连合核(DCN),一侧脑桥吻侧以Barrington核为中心的背外侧被盖区(TLD)和臂旁外侧核(PBL)注入HRP溶液,发现DCN注射例在Barrington核出现密布的标记细胞和终末,PBL出现较密的标记终末。TLD注射例在L_6和骶髓DCN及中间带(IM)出现由标记细胞和终末形成的带状标记区。PBL注射例在L_6和骶髓DCN及IM仅出现标记细胞。后两组实验还在L_6和骶髓Ⅰ层发现少量标记细胞。本文对上述结果结合已往的研究进行了分析,提出下列几点认识:1.本文首次从形态学上证明了以Barrington核为中枢的排尿反射回路:膀胱初级传入神经元→DCN、IM(Ⅱ级)中继神经元→Barrington核→IM(以中间带外侧核IML为主)节前神经元→节后神经元。2.根据本文结果并结合以前的工作推断,盆腔内脏感觉经DCN、IM和Ⅰ层的神经元中继后,投射至PBL。3.发现L_6和骶髓DCN、IM是和盆腔脏器联系的复合体,暂命名为“内脏面”,它既与外周发生广泛的传出、传入联系,又有较多的中继神经元向Barrington核和PBL投射,并接受Barrington核的下行投射。此下行纤维同时投射于Onuf核。本文对“内脏面”提出了自己的见解和今后深入研究的目标。此外,比较系统地讨论了后连合核的机能。

HRP solution was injected into the dorsal commissural nucleus (DCN) of segment L_6 or S_1 of the spinal cord and laterodorsal tegmental area(TLD)——take the Barrington's nucleus as its center and lateral parabrachial nucleus (PBL) of the rostral pons in different individuals of the rats. After HRP was injected into the DCN, labelled neurons and dense terminals were found in Barrington's nucleus, and labelled terminals appeared in the PBL. When the unilateral TLD was injected the labelled cells and terminals were found in the DCN and bilateral intermediate zone (IM), and formed a band of labelled neurons and terminals. When the PBL was injected the labelled neurons were observed in the DCN and bilateral IM. A few labelled neurons were found in lamina Ⅰ in the latter two experimental groups.Based on the present and previous studies, the authors got the following understandings:1. Morphylogically, the present study for the first time demonstrated that, the micturition reflex arch through the pontine consists of following parts: the primary afferent neurons of the bladder→secondary relay neurons of DCN→Barrington's nucleus→IM (mainly IML) parasympathetic preganglionic neurons→parasympathetic postganglionic neurons.2. According to the present and previous researches, the authors conjecture that, the secondary fibers of visceral sensation of the pelvic organs originate from the neurons of DCN, IM and lamina I and project into the PBL.3. According to the facts mentioned above, we presume that the DCN and bilateral IM constitute a complex and named it the 'visceral field', and which is closely associated with the pelvic organs. This field has widespread connections with the peripheral efferent and afferent nerves. On the other hand, i t contains a lot of relay neurons projecting into Barrington's nucleus and PBL and receives the terminals of descending fibers of the neurons of the Barrington's nucleus. The descending fibers also project into the Onuf's nucleus.In addition, the present study disscussed the complicated functions of the DCN systematically.