Liu Zhen, Liu Huaxiang, Li Zhenzhong
Department of Anatomy, Shandong University School of Medicine, 44 West Wenhua Road, Jinan, 250012, Shandong Province, China.
Cell Mol Neurobiol. 2008 Nov;28(7):939-47. doi: 10.1007/s10571-008-9268-z. Epub 2008 Mar 1.
The interactions between primary sensory neurons and cardiac myocytes are still unclear. In the present study, the co-culture model of dorsal root ganglion (DRG) explant and cardiac myocytes was used to characterize the morphological relationship between primary sensory nerve endings and cardiac myocytes and to investigate whether cardiac myocytes could induce substance P (SP) and calcitonin gene-related peptide (CGRP) synthesis in DRG neurons and release from DRG neurons in the neuromuscular co-cultures.
The formation of neuromuscular junctions was observed with scanning electron microscopy (SEM). SP and CGRP expression were detected by immunocytochemistry. Basal SP and CGRP release and capsaicin-evoked SP and CGRP release were analyzed by radioimmunoassay (RIA).
In this study, neuromuscular junctions were observed in the co-cultures of DRG explant and cardiac myocytes. SP-immunoreactive (IR) and CGRP-IR neurons were detected in both neuromuscular co-cultures and DRG explant cultures, but the number of SP-IR and CGRP-IR neurons migrating from DRG explant was significantly increased in neuromuscular co-cultures. Capsaicin-evoked SP and CGRP release but not basal SP and CGRP release in neuromuscular co-cultures increased significantly as compared with that in the cultures of DRG explant alone.
The results implicated that the morphological relationship between sensory nerve terminal and cardiac myocyte is much more close in vitro than it is in vivo. Cardiac myocytes may induce sensory neuropeptide synthesis and capsaicin-evoked neuropeptide release in neuromuscular co-cultures. Further experiment needs to be performed about the significance of neuropeptide synthesis and capsaicin-evoked neuropeptide release induced by target cardiac myocytes.
初级感觉神经元与心肌细胞之间的相互作用仍不清楚。在本研究中，采用背根神经节（DRG）外植体与心肌细胞的共培养模型来表征初级感觉神经末梢与心肌细胞之间的形态学关系，并研究在神经肌肉共培养中，心肌细胞是否能诱导DRG神经元中P物质（SP）和降钙素基因相关肽（CGRP）的合成以及从DRG神经元中释放。
用扫描电子显微镜（SEM）观察神经肌肉接头的形成。通过免疫细胞化学检测SP和CGRP的表达。采用放射免疫分析法（RIA）分析基础SP和CGRP释放以及辣椒素诱发的SP和CGRP释放。
在本研究中，在DRG外植体与心肌细胞的共培养物中观察到神经肌肉接头。在神经肌肉共培养物和DRG外植体培养物中均检测到SP免疫反应性（IR）和CGRP-IR神经元，但在神经肌肉共培养物中，从DRG外植体迁移的SP-IR和CGRP-IR神经元数量显著增加。与单独的DRG外植体培养物相比，神经肌肉共培养物中辣椒素诱发的SP和CGRP释放显著增加，但基础SP和CGRP释放无显著变化。
结果表明，感觉神经末梢与心肌细胞之间的形态学关系在体外比在体内更为密切。心肌细胞可能在神经肌肉共培养中诱导感觉神经肽的合成和辣椒素诱发的神经肽释放。关于靶心肌细胞诱导神经肽合成和辣椒素诱发神经肽释放的意义，还需要进一步实验。
