Protoplasmic Astrocytes in CA1 Stratum Radiatum Occupy Separate Anatomical Domains

By E. Bushong, M. Martone, Y. Jones, Mark Ellisman. Journal of Neuroscience, 2002

1,526 citations recorded by the source corpus.

Protoplasmic astrocytes are increasingly thought to interact extensively with neuronal elements in the brain and to influence their activity. Recent reports have also begun to suggest that physiologically, and perhaps functionally, diverse forms of these cells may be present in the CNS. Our current understanding of astrocyte form and distribution is based predominately on studies that used the astrocytic marker glial fibrillary acidic protein (GFAP) and on studies using metal-impregnation techniques. The prevalent opinion, based on studies using these methods, is that astrocytic processes overlap extensively and primarily share the underlying neuropil. However, both of these techniques have serious shortcomings for visualizing the interactions among these structurally complex cells. In the present study, intracellular injection combined with immunohistochemistry for GFAP show that GFAP delineates only ∼15% of the total volume of the astrocyte. As a result, GFAP-based images have led to incorrect conclusions regarding the interaction of processes of neighboring astrocytes. To investigate these interactions in detail, groups of adjacent protoplasmic astrocytes in the CA1 stratum radiatum were injected with fluorescent intracellular tracers of distinctive emissive wavelengths and analyzed using three-dimensional (3D) confocal analysis and electron microscopy. Our findings show that protoplasmic astrocytes establish primarily exclusive territories. The knowledge of how the complex morphology of protoplasmic astrocytes affects their 3D relationships with other astrocytes, oligodendroglia, neurons, and vasculature of the brain should have important implications for our understanding of nervous system function.

Subfields: Cellular and Molecular Neuroscience, Neurology, Physiology

View Paper: https://www.semanticscholar.org/paper/d442b1665458949797297e3dd5c5d619068872b5

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Citations in the corpus

Pattern-specific loss of aquaporin-4 immunoreactivity distinguishes neuromyelitis optica from multiple sclerosis. (2007, background): “AQP4 is concentrated at the astrocytic endfeet, which are typically GFAP-negative (Frigeri et al., 1995; Bushong et al., 2002; Simard et al., 2003).”
Astrocytes are endogenous regulators of basal transmission at central synapses. (2011, neutral): “Astrocytes were identified as cells with extensive ramifications and a process associated with a blood vessel (Bushong et al., 2002).”
Astrocyte activation and reactive gliosis (2005, background): “The IF network becomes very prominent in particular in the main processes and the soma of astrocytes (Bushong et al., 2002, 2004) (Fig.”
The mystery and magic of glia: a perspective on their roles in health and disease. (2008, background): “A single astrocyte extends thousands of fine membranous processes that ensheath synapses and fine blood vessels and help fill the neuropil (Araque et al., 1999; Ventura and Harris, 1999; Bushong et al., 2002).”
Astrocytes: biology and pathology (2009, background): “In hippocampus or cortex many finely branching processes from a single astrocyte are estimated to contact several hundred dendrites from multiple neurons and to envelope 100,000 or more synapses [34, 91, 172].”
Glia and pain: Is chronic pain a gliopathy? (2013, background): “Glial cells in the CNS consist of 3 major groups: astrocytes, microglia, and oligodendrocytes [69].”
Physiology of Astroglia. (2018, neutral): “In the CA1 hippocampal region, fusiform, elongated, and spherical cells were distinguished (264, 1232); many more morphological appearances are observed throughout the brain (476, 1270).”
NG2 cells generate both oligodendrocytes and gray matter astrocytes (2007, background): “NG2+Cre+ cells generate protoplasmic but not fibrous astrocytes In addition to oligodendrocytes, we observed in NG2creBAC:Z/EG double tg mice numerous EGFP+NG2– cells with highly branched, fine, bushy processes resembling protoplasmic astrocytes (Bushong et al., 2002).”
Synaptic Islands Defined by the Territory of a Single Astrocyte (2007, background): “Dye filling of adjacent hippocampal astrocytes has shown that astrocytes are organized in a nonoverlapping tile-like manner and that one hippocampal astrocyte can contact in excess of 100,000 synapses (Bushong et al., 2002).”
Glial regulation of the cerebral microvasculature (2007, background): “One aspect of glial biology is that gray matter astrocytes extend over nonoverlapping spatial domain”