Alakuijala Anniina, Palgi Mari, Wegelius Katri, Schmidt Matthias, Enz Ralf, Paulin Lars, Saarma Mart, Pasternack Michael
Institute of Biotechnology, P.O. Box 56, FI-00014 University of Helsinki, Finland.
Brain Res Dev Brain Res. 2005 Jan 1;154(1):15-23. doi: 10.1016/j.devbrainres.2004.09.010.
Ionotropic GABA(C) receptors are composed of rho1, rho2 and rho3 subunits. Although the distribution of rho subunit mRNAs in the adult brain has been studied, information on the developmental regulation of different rho subunits in the brain is scattered and incomplete. Here, GABA(C) receptor rho subunit expression was studied in the developing rat brain. In situ hybridization on postnatal brain slices showed rho2 mRNA expression from newborn in superficial gray layer (SGL) of superior colliculus (SuC), and from the first postnatal week in the hippocampal CA1 region and pretectal nucleus of the optic tract. rho2 mRNA was also expressed in the adult dorsal lateral geniculate nucleus. Quantitative RT-PCR revealed expression of all three rho subunits in the hippocampus and superior colliculus from the first postnatal day. In the hippocampus, rho2 mRNA expression clearly dominated over rho1 and rho3, whereas in the superior colliculus, rho1 mRNA expression levels were similar to rho2. In both areas, a clear up-modulation of rho2 and rho3 mRNA during the first postnatal week was detected. GABA(C) receptor protein expression was confirmed in adult hippocampus, superior colliculus and dorsal lateral geniculate nucleus by immunohistochemistry. Our results demonstrate for the first time the expression of all three rho subunit mRNAs in several regions of the developing and adult rat brain. Our quantitative data allows assessment of putative subunit combinations in the superior colliculus and hippocampus. From the selective distribution of rho subunits, it may be hypothesized that GABA(C) receptors are specifically involved in aspects of visual image motion processing in the rat brain.
离子型GABA(C)受体由rho1、rho2和rho3亚基组成。尽管已对成体脑中rho亚基mRNA的分布进行了研究，但关于脑中不同rho亚基发育调控的信息零散且不完整。在此，我们研究了发育中大鼠脑内GABA(C)受体rho亚基的表达。对出生后脑切片进行原位杂交显示，rho2 mRNA在出生时即在上丘浅层灰质层（SGL）表达，出生后第一周开始在海马CA1区和视束前顶盖核表达。rho2 mRNA在成年背外侧膝状核也有表达。定量逆转录聚合酶链反应显示，出生后第一天起海马和上丘中所有三种rho亚基均有表达。在海马中，rho2 mRNA的表达明显高于rho1和rho3，而在上丘中，rho1 mRNA的表达水平与rho2相似。在这两个区域，均检测到出生后第一周rho2和rho3 mRNA明显上调。通过免疫组织化学证实了成年海马、上丘和背外侧膝状核中有GABA(C)受体蛋白表达。我们的结果首次证明了所有三种rho亚基mRNA在发育中和成年大鼠脑的几个区域中的表达。我们的定量数据有助于评估上丘和海马中假定的亚基组合。根据rho亚基的选择性分布，可以推测GABA(C)受体在大鼠脑视觉图像运动处理方面具有特定作用。
