Glutamine Synthetase in Oligodendrocytes and Astrocytes: New Biochemical and Immunocytochemical Evidence

Abstract

The results of recent immunocytochemical experiments suggest that glutamine synthetase (GS) in the rat CNS may not be confined to astrocytes. In the present study, GS activity was assayed in oligodendrocytes isolated from bovine brain and in oligodendrocytes, astrocytes, and neurons isolated from rat forebrain, and the results were compared with new immunochemical data. Among the cells isolated from rat brain, astrocytes had the highest specific activities of GS, followed by oligodendrocytes. Oligodendrocytes isolated from white matter of bovine brain had GS specific activities almost fivefold higher than those in white matter homogenates. Immunocytochemical staining also showed the presence of GS in both oligodendrocytes and astrocytes in bovine forebrain, in three white-matter regions of rat brain, and in Vibratome sections as well as paraffin sections.

Autophagy was activated in injured astrocytes and mildly decreased cell survival following glucose and oxygen deprivation and focal cerebral ischemia

“…62 High levels of the enzyme glutamine synthetase are found in astrocytes, which in conjunction with a specific glutamate transporter, remove and detoxify extracellular glutamate and provide the neuronal substrate glutamine, as part of the glutamate/glutamine cycle. 64,65 Astrocytes store glycogen and have the potential to provide lactate as an alternative aerobic energy substrate for neurons during recovery, as well as to maintain the osmotic environment. [67][68][69] Astrocytes produce a variety of cytokines and growth factors and function in the CNS as mediators of immune and inflammatory responses that may contribute to both neurotoxic and neuroprotective effects.…”

Chemoarchitecture of glial fibrillary acidic protein (GFAP) and glutamine synthetase in the rat optic nerve: An immunohistochemical study

“…However, GS immunoreactivity in oligodendrocytes was demonstrated in the rat central nervous system, including the optic tract, in the 1990s [50][51] . GS immunoreactivity in oligodendrocytes was subsequently reported in the optic nerve and optic chiasm.…”

Monoacylglycerol Lipase Limits the Duration of Endocannabinoid-Mediated Depolarization-Induced Suppression of Excitation in Autaptic Hippocampal Neurons

“…This ABHD6 staining may in fact be glial in nature. To test this, we costained with glutamine synthetase, a marker for some astrocytes and oligodendrocytes (Norenberg and Martinez-Hernandez, 1979;Fages et al, 1988;Tansey et al, 1991). However, we found that ABHD6 and glutamine synthetase staining were mutually exclusive (Fig.…”