Naus C C, Miller F D, Morrison J H, Bloom F E
Division of Preclinical Neuroscience and Endocrinology, Scripps Clinic, La Jolla, California 92037.
J Comp Neurol. 1988 Mar 15;269(3):448-63. doi: 10.1002/cne.902690311.
The chemical differentiation of somatostatin (SS) neurons in rat neocortex was characterized by molecular biochemical and morphological methods. Northern (RNA) blotting indicates that regional distribution of SS mRNA correlates with the known distribution patterns of SS-containing neurons in the adult, while similar analysis of poly (A)+ RNA isolated from telencephalon at various times postnatally shows an increase between P9 and P15, with a slight decrease in the adult. In situ hybridization with a probe specific to SS mRNA, and immunohistochemistry using antisera specific for the N-terminally extended form of SS, SS28, and SS28(1-12), were used to detect neocortical neurons containing this mRNA or its translation product. The appearance of SS mRNA is coincident with detectable immunoreactivity for SS peptides. The expression of the SS gene by cortical neurons occurs in two waves. From P1 to P11, hybridizing neurons are predominant below the cortical plate in the developing infragranular layers. Immunohistochemical analysis of immunoreactivity to SS28 reveals a significant development of this neocortical system by late gestation (E20). At this point SS28(1-12), the predominant SS form detected, is mainly in neurons of the subplate, with less detectable immunoreactivity in the intermediate zone and cortical plate. By P2, neurons in the subplate exhibit detectable SS28 and SS28(1-12). Although immunoreactive perikarya are no longer detectable at P2 in the cortical plate or marginal zone, a very dense plexus of SS28(1-12) fibers is seen in the subplate, marginal zone, and intermediate zone; relatively few immunoreactive fibers are found in the cortical plate. By P12, a dramatic shift occurs; a large supragranular population of these SS neurons is observed by both mRNA and antibody methods, as is a subsequent decrease in number in the adult. The shift in immunoreactivity occurs with supragranular SS28-containing neurons now prominent, and SS28(1-12)-containing neurons and fibers greatly diminished. The number of neurons containing SS mRNA or SS28 immunoreactivity decreases from P12 to adult, when these neurons exhibit a bilaminar distribution. Neurons immunoreactive for SS28(1-12) are now sparsely distributed throughout the cortex, while SS28(1-12) fibers densely innervate layers I and V/VI.
采用分子生化和形态学方法对大鼠新皮质中生长抑素（SS）神经元的化学分化进行了表征。Northern（RNA）印迹分析表明，SS mRNA的区域分布与成年大鼠中含SS神经元的已知分布模式相关，而对出生后不同时间从端脑分离的多聚腺苷酸（poly(A)+）RNA进行的类似分析显示，在出生后第9天（P9）至第15天之间有所增加，成年后略有下降。使用针对SS mRNA的特异性探针进行原位杂交，以及使用针对N端延伸形式的SS、SS28和SS28(1 - 12)的抗血清进行免疫组织化学，以检测含有这种mRNA或其翻译产物的新皮质神经元。SS mRNA的出现与SS肽可检测到的免疫反应性同时发生。皮质神经元中SS基因的表达分两个阶段。从P1到P11，杂交神经元在发育中的颗粒下层皮质板下方占主导地位。对SS28免疫反应性的免疫组织化学分析显示，到妊娠晚期（E20），这个新皮质系统有显著发育。此时检测到的主要SS形式SS28(1 - 12)主要存在于板下层神经元中，在中间带和皮质板中可检测到的免疫反应性较少。到P2时，板下层神经元表现出可检测到的SS28和SS28(1 - 12)。尽管在P2时皮质板或边缘带中不再能检测到免疫反应性胞体，但在板下层、边缘带和中间带可见非常密集的SS28(1 - 12)纤维丛；在皮质板中发现的免疫反应性纤维相对较少。到P12时，发生了显著变化；通过mRNA和抗体方法均观察到大量这些SS神经元位于颗粒上层，随后在成年期数量减少。免疫反应性的变化发生时，含SS28的颗粒上层神经元变得突出，而含SS28(1 - 12)的神经元和纤维大大减少。从P12到成年期，含有SS mRNA或SS28免疫反应性的神经元数量减少，此时这些神经元呈现双分层分布。对SS28(1 - 12)免疫反应性的神经元现在稀疏分布于整个皮质，而SS28(1 - 12)纤维密集支配I层和V/VI层。
