Quartu Marina, Serra Maria Pina, Boi Marianna, Ibba Viviana, Melis Tiziana, Del Fiacco Marina
Department of Cytomorphology, University of Cagliari, Cittadella Universitaria di Monserrato, Monserrato (Cagliari), Italy.
BMC Neurosci. 2008 Nov 6;9:108. doi: 10.1186/1471-2202-9-108.
The polysialylated neuronal cell adhesion molecule (PSA-NCAM) is considered a marker of developing and migrating neurons and of synaptogenesis in the immature vertebrate nervous system. However, it persists in the mature normal brain in some regions which retain a capability for morphofunctional reorganization throughout life. With the aim of providing information relevant to the potential for dynamic changes of specific neuronal populations in man, this study analyses the immunohistochemical occurrence of PSA-NCAM in the human trigeminal ganglion (TG) and brainstem neuronal populations at prenatal and adult age.
Western blot analysis in human and rat hippocampus supports the specificity of the anti-PSA-NCAM antibody and the immunodetectability of the molecule in postmortem tissue. Immunohistochemical staining for PSA-NCAM occurs in TG and several brainstem regions during prenatal life and in adulthood. As a general rule, it appears as a surface staining suggestive of membrane labelling on neuronal perikarya and proximal processes, and as filamentous and dot-like elements in the neuropil. In the TG, PSA-NCAM is localized to neuronal perikarya, nerve fibres, pericellular networks, and satellite and Schwann cells; further, cytoplasmic perikaryal staining and positive pericellular fibre networks are detectable with higher frequency in adult than in newborn tissue. In the adult tissue, positive neurons are mostly small- and medium-sized, and amount to about 6% of the total ganglionic population. In the brainstem, PSA-NCAM is mainly distributed at the level of the medulla oblongata and pons and appears scarce in the mesencephalon. Immunoreactivity also occurs in discretely localized glial structures. At all ages examined, PSA-NCAM occurs in the spinal trigeminal nucleus, solitary nuclear complex, vestibular and cochlear nuclei, reticular formation nuclei, and most of the precerebellar nuclei. In specimens of different age, the distribution pattern remains fairly steady, whereas the density of immunoreactive structures and the staining intensity may change and are usually higher in newborn than in adult specimens.
The results obtained show that, in man, the expression of PSA-NCAM in selective populations of central and peripheral neurons occurs not only during prenatal life, but also in adulthood. They support the concept of an involvement of this molecule in the structural and functional neural plasticity throughout life. In particular, the localization of PSA-NCAM in TG primary sensory neurons likely to be involved in the transmission of protopathic stimuli suggests the possible participation of this molecule in the processing of the relevant sensory neurotransmission.
多唾液酸神经细胞黏附分子（PSA-NCAM）被认为是未成熟脊椎动物神经系统中发育、迁移的神经元以及突触形成的标志物。然而，它在成熟正常大脑的某些区域持续存在，这些区域在整个生命过程中都保留着形态功能重组的能力。为了提供与人类特定神经元群体动态变化潜力相关的信息，本研究分析了产前和成年期人类三叉神经节（TG）和脑干神经元群体中PSA-NCAM的免疫组织化学出现情况。
对人类和大鼠海马体的蛋白质印迹分析支持了抗PSA-NCAM抗体的特异性以及该分子在死后组织中的免疫可检测性。PSA-NCAM的免疫组织化学染色在产前和成年期的TG和几个脑干区域均有出现。一般来说，它表现为一种表面染色，提示在神经元胞体和近端突起上的膜标记，以及在神经毡中呈丝状和点状元素。在TG中，PSA-NCAM定位于神经元胞体、神经纤维、细胞周围网络以及卫星细胞和施万细胞；此外，与新生组织相比，在成年组织中可更频繁地检测到胞体细胞质染色和阳性细胞周围纤维网络。在成年组织中，阳性神经元大多为中小型，约占神经节细胞总数的6%。在脑干中，PSA-NCAM主要分布在延髓和脑桥水平，在中脑则很少见。免疫反应性也出现在离散定位的神经胶质结构中。在所有检查的年龄段，PSA-NCAM都出现在三叉神经脊束核、孤束核复合体、前庭和蜗神经核、网状结构核以及大多数小脑前核中。在不同年龄的标本中，分布模式保持相当稳定，而免疫反应性结构的密度和染色强度可能会发生变化，通常在新生标本中比成年标本中更高。
获得的结果表明，在人类中，PSA-NCAM在中枢和外周神经元的选择性群体中的表达不仅发生在产前，也发生在成年期。它们支持了该分子在整个生命过程中参与神经结构和功能可塑性的概念。特别是，PSA-NCAM在可能参与原始性刺激传递的TG初级感觉神经元中的定位表明该分子可能参与相关感觉神经传递的处理。
