Hippocampal CA3 and CA2 have distinct bilateral innervation patterns to CA1 in rodents
Hippocampal CA3 and CA2 have distinct bilateral innervation patterns to CA1 in rodents
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DOI：
10.1111/j.1460-9568.2012.07993.x
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发表时间：
2012-03-01
影响因子：
3.4
通讯作者：
Hirase, Hajime
中科院分区：
文献类型：
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作者：
Shinohara, Yoshiaki;Hosoya, Aki;Hirase, Hajime
用逆行示踪法研究成年雄性LongEvans大鼠同侧和对侧海马CA3CA1和CA2CA1的投射。将逆行示踪剂霍乱毒素B亚单位注入背侧CA1层和放射层，可在同侧和对侧CA3和CA2标记以锥体细胞为主的标记细胞。CA3神经支配CA1的对侧和同侧前后神经分布相似。产生CA1层神经支配的海马体固有细胞中有15%~20%是CA2锥体细胞，而CA1辐射层神经支配的CA2细胞仅占3%。在CACNG5启动子控制下表达GFP的转基因小鼠中，CA2锥体细胞优先投射到CA1层，其中CA2细胞高表达GFP。比较同侧与对侧的投射比。对于CA3CA1连接，我们发现CA1背侧放射层接受更多的同侧投射，而CA1层东侧接受更多的对侧神经支配。有趣的是，CA2CA1东方层和CA2CA1放射层均以同侧联系为主。这些结果表明，CA2锥体细胞在海马内的主要靶点是同侧CA1层，而CA3细胞投射到双侧CA1区的差异更大。这种神经支配模式可能提示CA1锥体细胞顶端树突和基底部树突的不同树突信息处理。
Ipsilateral and contralateral hippocampal CA3CA1 and CA2CA1 projections were investigated in adult male LongEvans rats by retrograde tracing. Injection of the retrograde tracer cholera toxin subunit B in the strata oriens and radiatum of dorsal CA1 resulted in labeling of predominantly pyramidal cells in ipsilateral and contralateral CA3 and CA2. The contralateral and ipsilateral anteriorposterior extents of CA3 innervation to CA1 were similar. Fifteen to twenty per cent of the hippocampus proper cells that give rise to CA1 stratum oriens innervation were CA2 pyramidal cells, whereas CA2 cells were a mere 3% for CA1 stratum radiatum innervation. The preferred projection of CA2 pyramidal cells to the CA1 stratum oriens was also manifested in transgenic mice that express GFP under the control of the CACNG5 promoter, in which CA2 cells express high amounts of GFP. The ratios of ipsilateral to contralateral projections were compared. For the CA3CA1 connection, we found that dorsal CA1 stratum radiatum received more ipsilateral projections whereas CA1 stratum oriens received more contralateral innervation. Interestingly, ipsilateral connections dominated for both CA2CA1 stratum oriens and CA2CA1 stratum radiatum. These results demonstrate that the primary intrahippocampal target of CA2 pyramidal cells is the ipsilateral CA1 stratum oriens, in contrast to CA3 cells which project more diversely to bilateral CA1 regions. Such innervation patterns may suggest differential dendritic information processing in apical and basal dendrites of CA1 pyramidal cells.