Sevoflurane Inhibits Glutamate-Aspartate Transporter and Glial Fibrillary Acidic Protein Expression in Hippocampal Astrocytes of Neonatal Rats Through the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) Pathway.

BACKGROUND: The mechanisms underlying general anesthesia-induced neurotoxicity are unclear. Astrocytes have been recognized as important contributors to neuronal development. Until now, the response of the astrocytes to neonatal general anesthetic exposure has been unreported.

METHODS: Postnatal day 7 rats received 2.5% sevoflurane for 6 hours. Expressions of glial fibrillary acidic protein (GFAP) and glutamate-aspartate transporter (GLAST) and phosphorylation of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway were detected on days 1, 3, 7, and 14 after sevoflurane inhalation. In addition, cultured astrocytes were exposed to 2.5% sevoflurane for 2 hours and GFAP, GLAST expressions, and JAK/STAT phosphorylation were evaluated. Furthermore, we pharmacologically disrupted JAK/STAT signaling in vivo by treatment with the JAK/STAT inhibitor AG490 and in vitro by treatment with JAK inhibitor I to detect the consequent expression of GFAP and GLAST.

RESULTS: Sevoflurane induced a robust decrease of GFAP and GLAST expression in hippocampal tissue compared with sham control groups at 1 to 14 days after sevoflurane exposure. Immunohistochemistry showed colocalization of GFAP, GLAST, and pSTAT3 in the hippocampal CA1 region. Western blot analysis also revealed a significant decrease of pJAK1, pJAK2, and pSTAT3 in the sevoflurane group. In vitro study showed that GFAP, GLAST, pJAK1, pJAK2, and pSTAT3 expressions in cultured astrocytes were remarkably decreased at 24 to 48 hours after sevoflurane treatment. Either AG490 or JAK inhibitor I significantly decreased expressions of GFAP and GLAST in hippocampus or cultured astrocytes.

CONCLUSIONS: Astrocytic GLAST was inhibited by sevoflurane in the hippocampus of neonatal rats. Inactivation of the JAK/STAT pathway possibly contributes to this effect of sevoflurane. Astrocytic dysfunction induced by sevoflurane may contribute to its neurotoxicity in the developing brain.