The Expression Of The Homeobox Gene Islet-1 In The Development Rat Striatum

Homeobox genes play fundamental roles in the development ofnervous system. They can be divided into several subfamilies, one ofwhich is the LIM homeobox subfamily.The LIM homeobox gene play crucial roles in determining diverseaspects of neuronal development both in vertebrates and invertebrates.The islet-1 gene is a member of the LIM homeobox gene family. In thepresent investigation, we studied the expression pattern of islet-1 protein,a member of the LIM homeodomain protein family, in the rat striatumduring development. The developmental expression of islet-1 in thestriatum is highly dynamic and complex in terms of spatial and temporalregulation.In our study, experimenting animals are divided into seven groups: E13-day,E15-day, E18-day, P0-day, P3-day, P6-day, and adult control group. We observeevery period in growing telencephalon especially ventral telencephalon bycommon histological method. In order to discuss islet-1 gene expression in therat striatum,We use immunohistochemistry method to further research. Ourpresent study indicts LIM homeobox gene islet-1 expressing in the rat forebrain,starting from the 13th day. During the stage, islet-1 positive cells exist in theventral telencephalon, but not in the fundament of cerebral cortex, that is thedorsal telencephalon. Following further development of central nerve system,islet-1 positive cells spread widely, and become more and more before boring,but decrease sharply after boring.Meanwhile, islet-1 protein expression differentiates in different parts ofstriatum. Most islet-1 positive cells exist in the place of striatum near to theventricle. The count of islet-1 positive cells taper from the center to periphery,so there is few in the periphery. The regional distinction of expression isespecially notably between the 18th embryo and delivery, and vanishes until the6th day after birth. Although the expression of the islet-1 gene decreases widely,there are still few positive cells in adult rats.Our study suggests islet-1 protein expresses widespreadly in the differentstriatum neurons early, including the precursor cells of cholinergic neurons andnon-cholinergic neurons. However, that expression limits in a few neurons ofstriatum ,accompanied by further nerve system differentiation, which possiblydemonstrates the later expression limited in cholinergic neurons. The expressionstyle is important for maintaining cholinergic neuron phenotype. On thecontrary, the down regulation of its expression is also significant fornon-cholinergic neuron phenotype.On the whole, we can know: first, islet-1 protein can express in the wholedeveloping course of the rat striatum;the second, the count of islet-1 positivecells are correlated much with its location and developing stage then;finally,islet-1 gene is much impossibly responsible for the formation and maintenanceof the rat striatum neuron phenotype.