Horackova M, Slavikova J, Byczko Z
Department of Physiology and Biophysics, Faculty of Medicine, Dalhouise University, Halifax, Nova Scotia, Canada.
Tissue Cell. 2000 Oct;32(5):377-88. doi: 10.1054/tice.2000.0126.
We used confocal laser scanning microscopy and fluorescent immunohistochemistry to study the developmental pattern and distribution of specific neuronal phenotypes within the intrinsic cardiac nervous system in whole-mount atrial preparations from newborn to 5 week old rats. Individual ganglia and neuronal cell bodies were localized by means of two general neuronal markers: protein gene product 9.5 (PGP) and microtubule-associated protein two (MAP). In rats < or =2 weeks old there were two main subpopulations of intrinsic neurons located in the intraatrial septum and around the origin of the superior vena cava. The more abundant was a population of strongly tyrosine hydroxylase (TH) immunoreactive (IR) neurons (10-40 microm in diameter) most of which were also PGP-IR. The second, less numerous (approximately 60-70% than the TH-IR group) type of neurons exhibited ChAT-IR which colocalized with MAP-IR. Towards the end of the second postnatal week and during the third, the ganglia containing these neurons became more numerous and their localization also included tissues around the origins of the inferior vena cava and the pulmonary veins, as well as both atrial walls close to the AV junction. During the second and third postnatal weeks, when the extrinsic innervation of the adrenergic and cholinergic phenotypes largely increases, the intrinsic innervation also changed greatly, and around the 21st postnatal day it appeared to acquire mature characteristics. The TH-IR neurons changed their characteristics and formed two types of ganglia. The larger ganglia containing large cells (20-40 microm in diameter) expressed TH-IR mostly close to their inner body surface (approximately 80-90% of identified neurons). Most of these neurons also expressed neuropeptide Y (NPY)-IR, specifically around their nuclei. The second type of small strongly TH-IR neurons (approximately 10% of all identified neurons) were contained in smaller groups (20-50 cells) which were usually embedded into much larger ganglia (100-400 cells), containing large (20-50 microm) neurons. Unlike all other intrinsic neurons, these small TH-IR cells did not exhibit any PGP-IR or MAP-IR. The number of ChAT-IR neurons increased at this stage, reaching approximately 90% of the neurons identified by the general neuronal markers. These neurons were surrounded by a rich network of cholinergic varicose nerve fibers, some of which were likely of an extrinsic origin. We have also identified relatively small ganglia expressing immunoreactivity to vasoactive intestinal polypeptide (VIP), and to substance P (SP). The presented data indicate that the phenotypes of intrinsic neurons in the rat heart change greatly during the first month of postnatal development. This may be at least partially related to the development and maturation of functional extrinsic nervous control of the heart.
我们使用共聚焦激光扫描显微镜和荧光免疫组织化学技术，研究了新生至5周龄大鼠全层心房标本中心脏固有神经系统内特定神经元表型的发育模式和分布。通过两种通用神经元标记物：蛋白基因产物9.5（PGP）和微管相关蛋白2（MAP）对单个神经节和神经元细胞体进行定位。在2周龄及以下的大鼠中，有两个主要的固有神经元亚群，位于房间隔和上腔静脉起始部周围。数量较多的是一群强酪氨酸羟化酶（TH）免疫反应性（IR）神经元（直径10 - 40微米），其中大多数也是PGP-IR。第二种神经元数量较少（约为TH-IR组的60 - 70%），表现出ChAT-IR，且与MAP-IR共定位。在出生后第二周结束时及第三周期间，含有这些神经元的神经节数量增多，其定位还包括下腔静脉和肺静脉起始部周围的组织，以及靠近房室交界处的两个心房壁。在出生后第二周和第三周，当肾上腺素能和胆碱能表型的外在神经支配大量增加时，固有神经支配也发生了很大变化，在出生后第21天左右，它似乎获得了成熟特征。TH-IR神经元改变了其特征，形成了两种类型的神经节。较大的神经节含有大细胞（直径20 - 40微米），TH-IR主要在其内部体表附近表达（约80 - 90%的已鉴定神经元）。这些神经元中的大多数还表达神经肽Y（NPY）-IR，特别是在其细胞核周围。第二种类型的小而强TH-IR神经元（约占所有已鉴定神经元的10%）包含在较小的群体中（20 - 50个细胞），这些群体通常嵌入到大得多的神经节（100 - 400个细胞）中，大神经节含有大（20 - 50微米）神经元。与所有其他固有神经元不同，这些小的TH-IR细胞不表现出任何PGP-IR或MAP-IR。在此阶段，ChAT-IR神经元数量增加，达到由通用神经元标记物鉴定的神经元的约90%。这些神经元被丰富的胆碱能曲张神经纤维网络包围，其中一些可能起源于外在神经。我们还鉴定出了对血管活性肠肽（VIP）和P物质（SP）有免疫反应性的相对较小的神经节。所呈现的数据表明，大鼠心脏固有神经元的表型在出生后发育的第一个月内发生了很大变化。这可能至少部分与心脏功能性外在神经控制的发育和成熟有关。
