Distribution of type 1 cannabinoid receptor (CB1)‐immunoreactive axons in the mouse hypothalamus
Distribution of type 1 cannabinoid receptor (CB1)‐immunoreactive axons in the mouse hypothalamus
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DOI：
10.1002/cne.21383
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发表时间：
2007-04
影响因子：
2.5
通讯作者：
G. Wittmann;L. Deli;I. Kalló;E. Hrabovszky;Masahiko Watanabe;Zsolt Liposits;C. Fekete
中科院分区：
文献类型：
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作者：
G. Wittmann;L. Deli;I. Kalló;E. Hrabovszky;Masahiko Watanabe;Zsolt Liposits;C. Fekete
1型大麻素受体（CB1）是脑内源性大麻素的主要受体；它主要发生在前末/终轴突，介导逆行神经元信号机制。大量的生理和电生理证据表明CB1在调节下丘脑功能中的关键作用。相反，含有CB1的轴突在下丘脑的分布基本上是未知的。因此，我们利用针对小鼠CB1 C末端31个氨基酸的抗血清，分析了小鼠下丘脑CB1免疫反应（IR）轴突的分布和超微结构特征。我们发现CB1‐IR轴突密集地支配着下丘脑的大部分核，除了视交叉上核和外侧乳头核，其中只有分散的CB1‐IR纤维。弓形核、腹内侧核、背内侧核、室旁核和正中隆起外区的CB1‐IR神经支配证实了CB1在调节能量稳态和神经内分泌功能中的重要作用。表征CB1 - IR纤维表型的超微结构研究证实，大多数CB1免疫反应出现在轴突的前端和末端部分。CB1‐IR钮扣形成轴突突触、轴突突触和轴体突触。对室旁核和弓形核中标记突触的分析发现，对称和非对称特化的数量大致相等。总之，本研究揭示了小鼠大脑大多数下丘脑核和正中隆起的密集和差异的CB1 - IR神经支配。在超微结构水平上，CB1‐IR轴突通过对称和非对称突触与下丘脑神经元建立通信，表明内源性大麻素在下丘脑神经元网络中发生逆行信号传导。[j] .中华神经医学杂志，2001,23(3):379 - 379。©2007 Wiley‐Liss, Inc。
Type 1 cannabinoid receptor (CB1) is the principal receptor for endocannabinoids in the brain; it mainly occurs in preterminal/terminal axons and mediates retrograde neuronal signaling mechanisms. A large body of physiological and electrophysiological evidence indicates the critical role of CB1 in the regulation of hypothalamic functions. Conversely, the distribution of CB1‐containing axons in the hypothalamus is essentially unknown. Therefore, we have analyzed the distribution and the ultrastructural characteristics of the CB1‐immunoreactive (IR) axons in the mouse hypothalamus by using an antiserum against the C‐terminal 31 amino acids of the mouse CB1. We found that CB1‐IR axons innervated densely the majority of hypothalamic nuclei, except for the suprachiasmatic and lateral mammillary nuclei, in which only scattered CB1‐IR fibers occurred. CB1‐IR innervation of the arcuate, ventromedial, dorsomedial, and paraventricular nuclei and the external zone of the median eminence corroborated the important role of CB1 in the regulation of energy homeostasis and neuroendocrine functions. Ultrastructural studies to characterize the phenotype of CB1‐IR fibers established that most CB1 immunoreactivity appeared in the preterminal and terminal portions of axons. The CB1‐IR boutons formed axospinous, axodendritic, and axosomatic synapses. Analysis of labeled synapses in the paraventricular and arcuate nuclei detected approximately equal numbers of symmetric and asymmetric specializations. In conclusion, the study revealed the dense and differential CB1‐IR innervation of most hypothalamic nuclei and the median eminence of the mouse brain. At the ultrastructural level, CB1‐IR axons established communication with hypothalamic neurons via symmetric and asymmetric synapses indicating the occurrence of retrograde signaling by endocannabinoids in hypothalamic neuronal networks. J. Comp. Neurol. 503:270–279, 2007. © 2007 Wiley‐Liss, Inc.