Astrocytes have complex structures with numerous branches, and their morphology is related to the CNS functions. In our laboratory, we have previously showed that activation of α₂-adrenoceptor (AR) inhibits the process formation of cultured astrocytes. However, the effects of dexmedetomidine (DEX), an α₂-AR agonist, on the astrocyte morphology in vivo remain unclear. Therefore, we investigated the impact of DEX on astrocyte morphology in vivo.
Mice were intraperitoneally injected with α₂-AR agonist DEX (1-100 µg/kg) and/or α₂-AR antagonist atipamezole (ATIP) (1 mg/kg). GFAP was stained on brain slices, and morphological parameters were evaluated using SMorph. Additionally, lucifer yellow (LY) was injected into individual astrocytes using microelectrodes to evaluate astrocyte volume.
DEX decreased surface area of GFAP cytoskeleton, length, and thickness of astrocyte processes. Morphological analysis using LY similarly showed a reduction in astrocyte volume without changes in cell body size. ATIP partially inhibited astrocyte morphological changes by DEX.
This study showed that DEX induces morphological change of astrocyte, primarily mediated by α₂-AR. However, since ATIP did not completely inhibit the morphological changes induced by DEX, other pathways, including the receptors other than α₂-AR, may be involved in it.