Moosmang S, Biel M, Hofmann F, Ludwig A
Institut für Pharmakologie und Toxikologie der Technischen Universität München, Germany.
Biol Chem. 1999 Jul-Aug;380(7-8):975-80. doi: 10.1515/BC.1999.121.
Hyperpolarization-activated cation currents, termed I(h), are observed in a variety of neurons. Four members of a gene family encoding hyperpolarization-activated cyclic-nucleotide-gated cation channels (HCN1-4) have been cloned. The regional expression and cellular localization of the four HCN channel types in mouse brain was investigated using in situ hybridization. The expression of HCN1 was restricted to the olfactory bulb, cerebral cortex, hippocampus, superior colliculus and cerebellum. In contrast, HCN2 transcripts were found at high levels nearly ubiquitously in the brain, and the strongest signals were seen in the olfactory bulb, hippocampus, thalamus and brain stem. HCN3 was uniformly expressed at very low levels throughout the brain. Finally, HCN4 transcripts were prominently expressed selectively in the thalamus and olfactory bulb. Some neurons expressed two or more HCN channel transcripts including hippocampal pyramidal neurons (HCN1, HCN2 and low levels of HCN 4) and thalamic relay neurons (HCN2 and HCN4). Our results demonstrate that each HCN channel transcript has a unique distribution in the brain. Furthermore, they suggest that the heterogeneity of neuronal I(h) may be, at least in part, due to the differential expression of HCN channel genes.
超极化激活的阳离子电流，称为I(h)，在多种神经元中都能观察到。编码超极化激活的环核苷酸门控阳离子通道（HCN1 - 4）的基因家族的四个成员已被克隆。利用原位杂交技术研究了小鼠脑中四种HCN通道类型的区域表达和细胞定位。HCN1的表达局限于嗅球、大脑皮层、海马体、上丘和小脑。相比之下，HCN2转录本在脑中几乎普遍高水平存在，在嗅球、海马体、丘脑和脑干中信号最强。HCN3在整个大脑中均以非常低的水平均匀表达。最后，HCN4转录本在丘脑和嗅球中选择性显著表达。一些神经元表达两种或更多种HCN通道转录本，包括海马锥体细胞（HCN1、HCN2和低水平的HCN4）和丘脑中继神经元（HCN2和HCN4）。我们的结果表明，每个HCN通道转录本在脑中都有独特的分布。此外，它们表明神经元I(h)的异质性可能至少部分归因于HCN通道基因的差异表达。
