Wang Q P, Guan J L, Shioda S
Department of Anatomy, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, 142-8555, Tokyo, Japan.
Neuroscience. 2000;97(3):553-63. doi: 10.1016/s0306-4522(99)00605-3.
We examined synaptic connectivity between cholinergic and serotonergic neurons in the dorsal raphe nucleus and the laterodorsal tegmental nucleus of the rat. To this purpose we employed two variations (the combination of pre-embedding immunogold-silver intensification with avidin-biotin-peroxidase complex technique and the combination of avidin-biotin-peroxidase/3, 3'-diaminobenzidine/silver-gold intensification with avidin-biotin-peroxidase/3,3'-diaminobenzidine reaction) of a double pre-embedding immunoelectron procedure, using primary antibodies against vesicular acetylcholine transporter and serotonin. At the light-microscopic level, serotonin-like immunoreactive neurons in the dorsal raphe nucleus appeared as reddish black and vesicular acetylcholine transporter-like immunoreactive axon terminals were brown colored using a combination of pre-embedding immunogold-silver technique and avidin-biotin-peroxidase complex technique. Serotonin-like immunoreactive fibers projected to the laterodorsal tegmental nucleus. At the electron microscopy level, with both methods we observed in the dorsal raphe nucleus vesicular acetylcholine transporter-immunopositive axon terminals in synaptic contact with serotonin-like immunoreactive dendrites and, to a lesser degree, with serotonin-like immunoreactive cell bodies. These synapses usually were of the symmetrical type. Occasionally we noted, next to vesicular acetylcholine transporter-immunopositive axon terminals, also immunonegative terminals synapsing with the serotonin-like immunoreactive dendrites. In the laterodorsal tegmental nucleus we found serotonin-like immunoreactive axon terminals and immunonegative terminals forming synapses with vesicular acetylcholine transporter-immunoreactive dendrites. Most synapses formed by the serotonin-like immunopositive terminals were of the asymmetrical type. Our results suggest that serotonergic neurons in the dorsal raphe nucleus and cholinergic neurons in the laterodorsal tegmental nucleus may reciprocally influence each other by means of synaptic connectivity. Such connectivity may serve to regulate pain sensation, or be involved in the regulation of the sleeping-waking cycle.
我们研究了大鼠中缝背核和外侧背盖核中胆碱能神经元与5-羟色胺能神经元之间的突触连接。为此，我们采用了双重包埋前免疫电子程序的两种变体（包埋前免疫金银增强与抗生物素蛋白-生物素-过氧化物酶复合物技术相结合，以及抗生物素蛋白-生物素-过氧化物酶/3,3'-二氨基联苯胺/银金增强与抗生物素蛋白-生物素-过氧化物酶/3,3'-二氨基联苯胺反应相结合），使用针对囊泡乙酰胆碱转运体和5-羟色胺的一抗。在光学显微镜水平，采用包埋前免疫金银技术和抗生物素蛋白-生物素-过氧化物酶复合物技术相结合的方法，中缝背核中5-羟色胺样免疫反应性神经元呈红黑色，囊泡乙酰胆碱转运体样免疫反应性轴突终末呈棕色。5-羟色胺样免疫反应性纤维投射到外侧背盖核。在电子显微镜水平，使用这两种方法，我们在中缝背核中观察到囊泡乙酰胆碱转运体免疫阳性轴突终末与5-羟色胺样免疫反应性树突以及程度较轻地与5-羟色胺样免疫反应性细胞体形成突触接触。这些突触通常是对称型的。偶尔我们注意到，在囊泡乙酰胆碱转运体免疫阳性轴突终末旁边，也有免疫阴性终末与5-羟色胺样免疫反应性树突形成突触。在外侧背盖核中，我们发现5-羟色胺样免疫反应性轴突终末和免疫阴性终末与囊泡乙酰胆碱转运体免疫反应性树突形成突触。由5-羟色胺样免疫阳性终末形成的大多数突触是不对称型的。我们的结果表明，中缝背核中的5-羟色胺能神经元和外侧背盖核中的胆碱能神经元可能通过突触连接相互影响。这种连接可能有助于调节痛觉，或参与睡眠-觉醒周期的调节。
