BIOLOGY OF DIFFERENT TYPES OF CELL DEATH IN CHICK EMBRYO SPINAL CORD

神经元存活所必需的神经营养因子通过突触传递。在这方面，促进突触形成和维持的机制对于理解神经元死亡的机制至关重要。研究表明，生物胺促进发育和成年动物中枢神经系统突触的形成和维持，而5-羟色胺（5-HT）2A受体介导5-HT的功能，如果是这样的话，5-HT 2A受体可能在单个突触水平上分布于脑的不同区域。传统的放射自显影和原位杂交技术不能准确定位5 HT 2A受体的分布。为了克服这一缺点，我们提出了针对5 HT 2A受体蛋白的抗体，并利用它们进行免疫组织化学。在大鼠大脑皮质几乎所有神经元都有5 HT_（2A）受体的免疫反应性。虽然传统的技术未能定位5 HT 2A受体，但生理学研究表明小脑中存在5 HT 2A受体。通过使用抗体浦肯野细胞强烈标记，即使在树突的最远端部分。我们在超微结构水平上的免疫组化研究表明，5 HT 2A受体位于单个突触的突触后结构的膜增厚之下。5-HT 2A受体在脑的各个部位都有表达，并介导5-HT维持突触结构的功能。

Neurotrophic factors necessary for survival of neurons are transferredacross synapses. In this connection the mechanism to facilitate formation and maintenance of synapses is crucial to understand the mechanism of neuronal death. We have shown that biogenic amines faciliteta synapse formation and maintenance in the central nervous system in developing and adult animals, and that serotonin (5HT)2A receptor mediates the function of 5HT.If it is the case, 5HT2A receptor could be located in a diverse region of brain at the level of single synapses. The conventional techniques such as autoradiography and in situ hybridization are not sensitive enough to locate the detailed distribution pattern of 5HT2A receptor. To overwhelm this drawback we raised antibodies against 5HT2A receptor protein, and utilized them for immunohistochemistry. In rat cerebral cortex virtually all the neurons have immunoreactivity of 5HT2A receptor. Although conventional technique have failed to locate 5HT2A receptor, physiological studies have suggested the presence of 5HT2A receptor in the cerebellum. By using the antibodies Purkinje cells were strongly labelled even in the most distal part of dendrites. Our immunohistochemical study at the ultrastructural level has shown that 5HT2A receptor was located just beneath the membrane thichnings of postsynaptic structure in single synapses. All the informations together 5HT2A receptor are expressed in all the region of brain even at the ultrastructural level, aand mediate the function of 5HT to maintain synaptic structures.