Agnati L F, Cortelli P, Pettersson R, Fuxe K
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Prog Neurobiol. 1995 Aug;46(6):561-74. doi: 10.1016/0301-0082(95)00017-p.
The present paper proposes that trophic interplay among cells may represent the final common pathway for both genetic and environmental influences, and hence new criteria for the understanding of central nervous system (CNS) connectivity can be suggested. In particular, trophic signals may make up the common "language" through which genetic and epigenetic influences mold the CNS during development and the adult life. Furthermore, it will put forward the hypothesis that the developmental trophic interplay among cells leads to the formation of trophic units in the adult brain. A trophic unit is defined as the smallest set of cells, within the CNS, which act in a complementary way to support each other's trophism. The trophic units consist of neurons, glial cells, blood vessels, extracellular matrix (ECM). In particular, ECM gives support to the thin elongated cell processes and gives rise to selective chemical bridges between cell surfaces or between cell surfaces and the extracellular milieu. The trophic unit is a plastic device that not only assures neuronal survival, but also operates to adapt neuronal networks to new tasks by controlling extension of neuronal processes, synapse turnover and ECM characteristics. These plastic responses depend on the interplay of all the elements that constitute the trophic units. The concept of trophic unit may help to understand some features of neurodegenerative diseases, for example, the clustering of tangles in the neocortex and in the entorhinal cortex of Alzheimer's patients [corrected].
本文提出，细胞间的营养相互作用可能代表了遗传和环境影响的最终共同途径，因此可以提出理解中枢神经系统（CNS）连接性的新标准。特别是，营养信号可能构成了一种通用的“语言”，通过这种语言，遗传和表观遗传影响在发育和成年期塑造中枢神经系统。此外，本文还将提出一个假设，即细胞间的发育性营养相互作用会导致成年大脑中营养单位的形成。营养单位被定义为中枢神经系统内最小的一组细胞，它们以互补的方式相互作用以支持彼此的营养作用。营养单位由神经元、神经胶质细胞、血管、细胞外基质（ECM）组成。特别是，细胞外基质为细长的细胞突起提供支持，并在细胞表面之间或细胞表面与细胞外环境之间形成选择性化学桥梁。营养单位是一种可塑性装置，它不仅确保神经元的存活，还通过控制神经元突起的延伸、突触更新和细胞外基质特性来使神经元网络适应新任务。这些可塑性反应取决于构成营养单位的所有元素之间的相互作用。营养单位的概念可能有助于理解神经退行性疾病的一些特征，例如，阿尔茨海默病患者新皮层和内嗅皮层中缠结的聚集[已修正]。
