Schindler M, Humphrey P P, Löhrke S, Friauf E
Glaxo Institute of Applied Pharmacology, Department of Pharmacology, University of Cambridge, UK.
Neuroscience. 1999 Mar;90(3):859-74. doi: 10.1016/s0306-4522(98)00483-7.
Somatostatin is a neuromodulator in the mammalian CNS. To date, genes for at least five different somatotrophin release inhibiting factor receptors, termed sst1-sst5, have been cloned. The rat sst2 receptor exists in two splice variants, sst(alpha)a) and sst2(b), which differ in their carboxy-termini. When heterologously expressed in Chinese hamster ovary-K1 cells, these splice variants show little difference in their operational characteristics. Recently, the distribution of the sst2(a) receptor was documented, yet at present no data are available about the distribution of the sst2(b) receptor in the CNS. Here, we present the characterization of a novel polyclonal anti-peptide antibody that is selective for the sst2(b) receptor splice variant. The antibody was raised against the unique intracellular carboxy-terminal portion of the receptor protein. Using this affinity-purified antibody in western blotting experiments, the sst2(b) receptor expressed in Chinese hamster ovary-K1 cells was shown to be a glycoprotein with a molecular weight centred at about 85,000. The antibody showed no cross-reactivity to any of the recombinant human sst1-5 receptors, the rat sst2(a) receptor or wild-type Chinese hamster ovary-K1 cells. Employing immunohistochemistry, we investigated the distribution of the sst2(b) receptor in the brain and spinal cord of adult rats. A distinct distribution was found throughout the rostrocaudal axis of the CNS. Somatodendritic as well as axonal staining was observed. Somatodendritic labelling was particularly obvious in the olfactory bulb, cerebral cortex, hippocampal formation, mesencephalic trigeminal nucleus and cerebellum, as well as in cranial and spinal motor areas. The results show that the distribution of the sst2(b) receptor partially overlaps with that of the sst2(b) receptor, although there were differences in a number of brain areas. The location of the sst2(b) receptor implies that it may mediate a modulatory role of somatostatin inhibitory releasing factor on sensory as well as motor functions.
生长抑素是哺乳动物中枢神经系统中的一种神经调质。迄今为止，至少已克隆出五种不同的生长激素释放抑制因子受体基因，分别称为sst1 - sst5。大鼠sst2受体存在两种剪接变体，sst2(a)和sst2(b)，它们的羧基末端不同。当在中国仓鼠卵巢 - K1细胞中异源表达时，这些剪接变体在其操作特性上几乎没有差异。最近，已记录了sst2(a)受体的分布，但目前尚无关于sst2(b)受体在中枢神经系统中分布的数据。在此，我们展示了一种对sst2(b)受体剪接变体具有选择性的新型多克隆抗肽抗体的特性。该抗体是针对受体蛋白独特的细胞内羧基末端部分产生的。在蛋白质印迹实验中使用这种亲和纯化的抗体，结果表明在中国仓鼠卵巢 - K1细胞中表达的sst2(b)受体是一种糖蛋白，其分子量集中在约85,000。该抗体对任何重组人sst1 - 5受体、大鼠sst2(a)受体或野生型中国仓鼠卵巢 - K1细胞均无交叉反应。利用免疫组织化学，我们研究了成年大鼠脑和脊髓中sst2(b)受体的分布。在中枢神经系统的前后轴上发现了明显的分布。观察到了树突体和轴突染色。树突体标记在嗅球、大脑皮层、海马结构、中脑三叉神经核和小脑中以及在颅神经和脊髓运动区域特别明显。结果表明，sst2(b)受体的分布与sst2(a)受体的分布部分重叠，尽管在一些脑区存在差异。sst2(b)受体的定位表明它可能介导生长抑素抑制释放因子对感觉和运动功能的调节作用。
