Nervous system

About: Nervous system is a research topic. Over the lifetime, 16729 publications have been published within this topic receiving 847181 citations.

Ecto-nucleotidases--molecular structures, catalytic properties, and functional roles in the nervous system.

Abstract: Publisher Summary This chapter discusses the molecular structures, catalytic properties, and functional roles of ecto-nucleotidases in the nervous system. Only one ecto-5’-nucleotidase gene is known in vertebrates. Ecto-5’-nucleotidase plays a critical role in the extracellular hydrolysis cascade of nucleotides and in neural development. Several families of ectonucleotidases function in the nervous system. They differ in their catalytic and other functional properties and consist of several members each. The chapter presents that nucleotidergic signaling pathways are widely distributed in the nervous system and that the ecto-nucleotidases play a significant part in it. The functional properties of the presently known ecto-nucleotidases and also of the sequenced but uncharacterized potential ecto-nucleotidases need to be investigated. An evaluation of their role in defined signaling pathways requires that the cellular location of the enzymes is determined. Knock-out mice in which individual ecto-nucleotidases have been deleted from the germline promise to be important tools to unravel their functional roles in the nervous system and also in other tissues.

Expression of neurofilament subunits in neurons of the central and peripheral nervous system: an immunohistochemical study with monoclonal antibodies.

Abstract: The extent to which all neurofilament (NF) subunits (NF68, NF150, NF200) are expressed by different populations of mature CNS and PNS neurons is controversial. We addressed this issue in immunohistochemical studies of mature bovine tissues using monoclonal antibodies specific for each bovine NF subunit. All three NF subunits were detected in the perikarya and neurites of both CNS and PNS neurons; they were seen in nearly all PNS neuronal perikarya, and in all identifiable CNS and PNS axons. Most, but not all, CNS neuronal perikarya contained each of these NF antigens. CNS neurons devoid of immunodetectable NF antigens were generally small. The presence of low levels of NF antigens in neurons with scant perikaryal cytoplasm may account for the apparent absence of NF immunoreactivity in some classes of neurons, although other explanations, such as microheterogeneity among NF proteins, could account for this finding. NF antigens were also seen in some cells of the diffuse neuroendocrine system (adrenal chromaffin cells and cells of the pars distalis and pars intermedia), but not in other cell types. We suggest that the expression of all three NF subunits is a common feature of CNS and PNS neurons and their processes, and of some cells of the diffuse neuroendocrine system. These findings have implications for hypotheses concerning the structure and function of the intermediate filaments of neurons, and for hypotheses concerning neurodegenerative diseases involving NF proteins.

Understanding axon guidance: are we nearly there yet?

Abstract: During nervous system development, neurons extend axons to reach their targets and form functional circuits. The faulty assembly or disintegration of such circuits results in disorders of the nervous system. Thus, understanding the molecular mechanisms that guide axons and lead to neural circuit formation is of interest not only to developmental neuroscientists but also for a better comprehension of neural disorders. Recent studies have demonstrated how crosstalk between different families of guidance receptors can regulate axonal navigation at choice points, and how changes in growth cone behaviour at intermediate targets require changes in the surface expression of receptors. These changes can be achieved by a variety of mechanisms, including transcription, translation, protein-protein interactions, and the specific trafficking of proteins and mRNAs. Here, I review these axon guidance mechanisms, highlighting the most recent advances in the field that challenge the textbook model of axon guidance.