Region-specific localization of glutamine synthetase immunoreactivity in the mouse olfactory bulb: implications for neuron-glia interaction in bulbar synaptic plasticity.

Glutamine synthetase (GS) critically regulates the metabolism of glutamate and gamma-amino butyric acid (GABA), which mediate synaptic plasticity in the olfactory bulb. In this study, GS immunolocalization in the mouse olfactory bulb was examined. The main and accessory subdivisions of the olfactory bulb possess GS-positive cells and processes in the plexiform-, the mitral- and the granule cell layers. GS has been demonstrated to show a predominantly astrocytic localization; its presence in the cell layers implicated in glutamatergic and GABAergic function therefore suggests that bulbar synaptic plasticity in mice may be regulated by astroglia and, together with other lines of evidence, point to the possibility of a functional astroglia-neuron system in the mouse olfactory bulb.