摘要
高亲和性神经营养因子受体Trk ,广泛存在分布于哺乳动物神经组织。研究表明 :随着动物进化程度的降低 ,亚型Trk受体的类型有所减少 ;在低等动物 ,关于环节动物 (Annelida)Trk受体存在与否、分布如何尚未见报道。以我国环节动物门典型代表参环毛蚓 (Pheretimaaspergillum)为研究对象 ,运用免疫细胞化学染色技术 ,在光镜下观察TrkA、TrkB、TrkC和TrkE阳性细胞和纤维的形态与分布。发现Trk存在于参环毛蚓的神经系统和非神经组织。各亚型分布有所差异 ,TrkA阳性神经细胞存在于咽下神经节和肠神经系 ,阳性神经纤维存在于腹神经索和肠神经系 ;TrkB阳性细胞存在于非神经组织的肠上皮 ;TrkC阳性神经细胞存在于脑、咽下神经节和肠神经细胞 ,阳性神经纤维存在于围咽神经环、腹神经索和肠神经系 ;TrkE阳性神经细胞存在于脑、阳性神经纤维存在于咽下神经节和腹神经索。上述研究结果表明 :Trk存在于进化程度较低的环节动物 ,Trk在进化上具有悠久的历史。各亚型Trk受体的不同分布提示不同部位的神经细胞受不同神经营养因子的作用。
Neurotrophins and their Trk receptors play a crucial role in the development and maintenance of the vertebrate nervous system.The high-affinity signal-transducing TrkA,TrkB,TrkC and TrkE receptors of neurotrophin are distributed widely in neural tissues and non-neural tissues of vertebrate.Trk receptors also are discovered in Arthropoda,Mollusca.The previous research results show that the number of subtype of Trk receptors decreases with the fall of evolutionary rank.Are there TrkA,TrkB,TrkC and TrkE receptors in Annelida?Which subtype in nervous tissue? Which subtype in non-nervous tissue? All these questions remains unclear.The present study was undertaken to investigate the occurrence and distribution of TrkA,TrkB,TrkC and TrkE in the Chinese earthworm(Pheretima aspergillum).The Pheretima aspergillum was used as the experimental animal.All animals were fed with paper pulp and gelatin in order to discharge earth and sand.They were deeply anesthetized with 10% ethanol and dissected.The samples were fixed in fixative containing 4% paraformaldehyde and 2% picric acid in 0.01 mol/L PBS(pH 7.2) at 4℃for 6 hours,transferred to 30% sucrose-PBS until completely infiltrated, and then they were embedded in OCT compound (USA),frozen quickly in liquid nitrogen and sectioned in 20 μm thickness in Leica-1100 cryostat (Pharmacia).Alternate serial sections were stained with polyclonal antibodys against TrkA,TrkB,TrkC and TrkE by employing ABC immunocytochemistry technique.The immunostained consecutive sections were observed and the positive cells and fibers were examined under light microscope.It was found that Trk was distributed in not only neural tissues but also non-neural tissues,TrkA receptor existed in subpharyngeal ganglion,ventral nerve cord,enteric neurons,nervous fibers between muscle cells,but not in cerebroganglion,TrkB only existed in intestinal epithelium,TrkC existed in cerebroganglion,subpharyngeal ganglion,ventral nerve cord,enteric neurons,nervous fibers between muscle cells,and TrkE neurons existed in cerebroganglion,while TrkE nerve fibers in subpharyngeal ganglion and ventral nerve cord.The results indicated that TrkA,TrkB,TrkC and TrkE receptors were distributed in Annelida with low evolutionary rank, and the evolution of neurotrophic factors-Trk regulating system may be traced back with a long history.Each of the different Trk proteins binds and is responsive to different neurotrophic factors.TrkA,TrkB and TrkC served as the primary receptor for NGF,BDNF and NT-3 respectively.TrkE also was the primary ligand for NGF.The fact that TrkA, TrkB, TrkC and TrkE were distributed in neuron populations of different portions of the Earthworm suggested that these neurons were influenced by different neurotrophic factors.The Earthworm possesses stronger regeneration ability than vertebrates when injured.TrkA, TrkB, TrkC and TrkE may provide important insights into regeneration common to neural and non-neural tissues.
出处
《动物学报》
SCIE
CAS
CSCD
北大核心
2001年第4期394-397,共4页
ACTA ZOOLOGICA SINICA
