Anesthetics are widely used in medical practice and experimental
research, yet the neurobiological basis governing their effects remains
obscure. We have here used quantitative phosphoproteomics to investigate
the protein phosphorylation changes produced by a 30 min isoflurane
anesthesia in the adult mouse hippocampus. Altogether 318
phosphorylation alterations in total of 237 proteins between sham and
isoflurane anesthesia were identified. Many of the hit proteins
represent primary pharmacological targets of anesthetics. However,
findings also enlighten the role of several other proteins-implicated in
various biological processes including neuronal excitability, brain
energy homeostasis, synaptic plasticity and transmission, and
microtubule function-as putative (secondary) targets of anesthetics. In
particular, isoflurane increases glycogen synthase kinase-3β (GSK3β)
phosphorylation at the inhibitory Ser(9) residue and regulates the
phosphorylation of multiple proteins downstream and upstream of this
promiscuous kinase that regulate diverse biological functions. Along
with confirmatory Western blot data for GSK3β and p44/42-MAPK
(mitogen-activated protein kinase; reduced phosphorylation of the
activation loop), we observed increased phosphorylation of
microtubule-associated protein 2 (MAP2) on residues (Thr(1620,1623))
that have been shown to render its dissociation from microtubules and
alterations in microtubule stability. We further demonstrate that
diverse anesthetics (sevoflurane, urethane, ketamine) produce
essentially similar phosphorylation changes on GSK3β, p44/p42-MAPK, and
MAP2 as observed with isoflurane. Altogether our study demonstrates the
potential of quantitative phosphoproteomics to study the mechanisms of
anesthetics (and other drugs) in the mammalian brain and reveals how
already a relatively brief anesthesia produces pronounced
phosphorylation changes in multiple proteins in the central nervous
system.