Select ionotropic glutamate AMPA/kainate receptors are expressed at the astrocyte-vessel interface

Ionotropic AMPA/kainate (KA) glutamate receptors are important for vasculature-astrocyte interaction in the central nervous system (CNS). To date, little is known about the expression of AMPA/KA receptors in the perivascular environment. Using double labeling immunohistochemistry on mouse and rat spinal cord sections, we show first evidence that perivascular astrocytic processes express specifically GluR4 (AMPA) and GluR5 (KA) subunits in both species. In contrast, astrocytes display GluR2/3 and GluR6/7 immunoreactivity throughout the cell but not limited to vascular profiles. Interestingly, KA2 immunoreactivity appears perivascular only in rats but not in mice. No perivascular labeling for any of the probed subunits was found in peripheral sciatic nerve. These data suggest that, in both mice and rats, few and select AMPA/KA subunits are uniquely positioned to mediate the effects of glutamate on astrocyte-vessel interactions.