Osborne J G, Kindy M S, Spruce B A, Hauser K F
Department of Anatomy and Neurobiology, University of Kentucky School of Medicine, Lexington 40517-0084.
Brain Res Dev Brain Res. 1993 Nov 19;76(1):1-12. doi: 10.1016/0165-3806(93)90117-s.
Proenkephalin mRNA and peptide products were examined in developing cells of the postnatal rat cerebellar cortex using in situ hybridization and immunocytochemistry. On day 7, proenkephalin mRNA was first detected as discrete cellular labeling in Golgi cells and as a diffuse hybridization signal over the Purkinje cell layer. On day 14, proenkephalin mRNA and peptide products primarily appeared in distinct subpopulations of Purkinje cells present in the posterior and lateral cerebellum. Similarly, in the external granular layer (EGL), enkephalin immunoreactivity was present only in the posterior and lateral portions of the cerebellum on day 14. However, proenkephalin mRNA was not detected in enkephalin-immunoreactive EGL cells. On day 21, the subset of Purkinje cells that expressed proenkephalin mRNA and peptides were distributed more uniformly throughout the cerebellum. On day 28, a few enkephalin-immunoreactive Purkinje cells were uniformly present throughout the cerebellum, but proenkephalin mRNA was not detected in most of these cells. The spatial gradients in proenkephalin mRNA expression evident in the Purkinje cells of younger rats were no longer present in 28-day-old rats. These findings are important, because endogenous opioids such as enkephalin have been previously shown to inhibit the growth of Purkinje cell dendrites and dendritic spines, and inhibit the rate of mitosis in EGL neuroblasts. Cells do not develop at uniform rates within the cerebellum. There are regional differences in the timing of the formation of the EGL, and in the morphogenesis of Purkinje cells. In conjunction with previous work, the present findings suggest that during development, the pattern of enkephalin immunoreactivity in Purkinje and EGL cells closely follows the spatial and temporal gradients of maturation in both these cell types. The emergence and disappearance of enkephalin immunoreactivity in Purkinje and EGL cells is spatially and temporally related, and coincides with proenkephalin mRNA expression in Purkinje cells. Thus, the transient and coordinated appearance of enkephalin in cerebellar Purkinje and EGL cells may contribute to regional differences in the rate of cerebellar maturation, and may help synchronize the developmental interactions between these two cell types.
利用原位杂交和免疫细胞化学技术，对出生后大鼠小脑皮质发育中的细胞中的脑啡肽原mRNA和肽产物进行了检测。在第7天，首次在高尔基细胞中检测到脑啡肽原mRNA呈离散的细胞标记，在浦肯野细胞层上呈弥漫性杂交信号。在第14天，脑啡肽原mRNA和肽产物主要出现在小脑后部和外侧的不同浦肯野细胞亚群中。同样，在第14天，在外部颗粒层（EGL）中，脑啡肽免疫反应性仅存在于小脑的后部和外侧部分。然而，在脑啡肽免疫反应性的EGL细胞中未检测到脑啡肽原mRNA。在第21天，表达脑啡肽原mRNA和肽的浦肯野细胞亚群在整个小脑中分布更为均匀。在第28天，少数脑啡肽免疫反应性浦肯野细胞均匀地分布在整个小脑中，但在这些细胞中的大多数中未检测到脑啡肽原mRNA。在幼鼠浦肯野细胞中明显的脑啡肽原mRNA表达的空间梯度在28日龄大鼠中不再存在。这些发现很重要，因为先前已证明内源性阿片类物质如脑啡肽可抑制浦肯野细胞树突和树突棘的生长，并抑制EGL神经母细胞的有丝分裂速率。小脑内细胞的发育速率并不一致。EGL形成的时间以及浦肯野细胞的形态发生存在区域差异。结合先前的研究工作，目前的发现表明，在发育过程中，浦肯野细胞和EGL细胞中脑啡肽免疫反应性的模式紧密跟随这两种细胞类型成熟的空间和时间梯度。浦肯野细胞和EGL细胞中脑啡肽免疫反应性的出现和消失在空间和时间上相关，并与浦肯野细胞中脑啡肽原mRNA的表达一致。因此，脑啡肽在小脑浦肯野细胞和EGL细胞中的短暂且协调的出现可能导致小脑成熟速率的区域差异，并可能有助于使这两种细胞类型之间的发育相互作用同步。
