Studies on Brain Histamine Neurons Using Gene-Targetted Mice

脑内的组胺能神经元系统由于与脑的多种功能有关而引起了神经科学家的兴趣。最近，已经开发出了H1和H2受体基因和组氨酸脱羧酶（HDC，一种组胺形成酶）基因被敲除的小鼠。本研究开展了组胺在睡眠-觉醒昼夜节律、自发行为、焦虑、学习记忆和惊厥中的作用的国际合作。到目前为止，事实证明，尽管没有HDC活性，但HDC-KO小鼠具有少量组胺水平，这表明存在另一种组胺来源。我们推测组胺是从肠道吸收的，因为用低组胺含量的饮食喂养KO小鼠降低了组织中的组胺水平。为了容易和可靠地比较野生和KO小鼠中获得的数据，产生了近交系129只小鼠。由于上述两个原因，小鼠的分配被推迟，但它们现在被送到合作者那里。2000年11月22日至25日，国际仙台组胺研讨会在仙台举行，本基金会全体成员参加了会议，并交流了信息和意见。

The histaminergic neuron system in the brain attracts interests of many neuroscientists, because it is related to various brain functions. Recently, mice with genes for H1 and H2 receptors and histidine decarboxylase (HDC, a histamine-forming enzyme) knocked out have been developed. In this research, international collaboration of functions of histamime in sleep-awakeness circadian rhythm, spontaneous behavior, anxiety, learning-memory and convulsions have been carried out. So far, it turned out that HDC-KO mice have a little level of histamine in spite of no HDC activity, suggesting that there is another source of histamine. We speculate that histamine is absorbed from the gut, because feeding the KO mice with a diet of low histamine content decreased the histamine levels in tissues. For easy and reliable comparison of data obtained in wild and KO mice, the inbred 129 mice were produced. By the two reqasons mentioned above, the distribution of the mice was delayed but they are now being sent to the collaborators. From November 22 to 25, 2000, International Sendai Histamine Symposium was held in Sendai, and all the members of this grant attended the Sympo sium and exchanged informations and ideas.