Jöhren O, Inagami T, Saavedra J M
Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD 20982, USA.
Brain Res Mol Brain Res. 1996 Apr;37(1-2):192-200. doi: 10.1016/0169-328x(95)00309-g.
To localize the gene expression of AT2 angiotensin II receptors in rat brain we performed in situ hybridization histochemistry using 35S-labeled antisense riboprobes. The AT2 receptor mRNA expression pattern was compared in consecutive brain sections, from 2 week old rats, with the receptor expression by means of [125I]Sar1-ANG II binding and displacement with AT2 selective ligands followed by autoradiography. Expression of AT2 receptor mRNA was found in several thalamic nuclei (ventral posterolateral, mediodorsal, central medial, paracentral, and paraventricular), the medial geniculate nuclei, the nucleus of the optic tract, the subthalamic nucleus, the interposed nucleus of the cerebellum, and in the inferior olive. In these areas the AT2 receptor gene expression corresponds well with [125I]Sar1-ANG II binding. In addition, AT2 receptor mRNA expression was found in the red nucleus where no [125I]Sar1-ANG II binding was present. No significant hybridization of the AT2 receptor antisense probe was found in septal nuclei, the locus coeruleus, the dorsolateral geniculate nucleus, or the cerebellar cortex, areas rich in [125I]Sar1-ANG II binding. Our results indicate that some brain regions may be involved in AT2 receptor formation, transporting the receptor protein to other brain areas. However, in most structures, both the formation and expression of receptors occur, suggesting the existence of local AT2 receptor circuits, or that of AT2 autoreceptors. Other structures express only the receptor protein, indicating that these AT2 receptors are produced elsewhere. Our present data are the basis for further studies on the clarification of AT2 receptor pathways in the brain.
为了定位大鼠脑中血管紧张素 II 2 型（AT2）受体的基因表达，我们使用 35S 标记的反义核糖探针进行了原位杂交组织化学实验。我们比较了 2 周龄大鼠连续脑切片中 AT2 受体 mRNA 的表达模式，以及通过 [125I]Sar1-ANG II 结合和用 AT2 选择性配体置换后进行放射自显影得到的受体表达情况。在几个丘脑核（腹后外侧核、背内侧核、中央内侧核、中央旁核和室旁核）、内侧膝状体核、视束核、丘脑底核、小脑间位核以及下橄榄核中发现了 AT2 受体 mRNA 的表达。在这些区域，AT2 受体基因表达与 [125I]Sar1-ANG II 结合情况良好对应。此外，在没有 [125I]Sar1-ANG II 结合的红核中也发现了 AT2 受体 mRNA 的表达。在富含 [125I]Sar1-ANG II 结合的隔核、蓝斑核、背外侧膝状体核或小脑皮质中，未发现 AT2 受体反义探针的显著杂交信号。我们的结果表明，一些脑区可能参与了 AT2 受体的形成，并将受体蛋白转运到其他脑区。然而，在大多数结构中，受体的形成和表达都存在，这表明存在局部 AT2 受体回路或 AT2 自身受体。其他结构仅表达受体蛋白，这表明这些 AT2 受体是在其他地方产生的。我们目前的数据为进一步阐明脑中 AT2 受体途径的研究奠定了基础。
