It is known that preconditional treatment with volatile
anesthetics can induce tolerance of the brain to
stroke. A previous study demonstrated that the involvement of
TREK-1, a two-pore domain K+ channel, in
sevoflurane preconditioning induced neuroprotection against focal
cerebral ischemia in rats. The present study testified whether TREK-2, another
anesthetic-target K+ channel, is also associated with volatile
anesthetic-induced neuroprotection, and further explored its potential mechanism. Rats preconditioned with
isoflurane were subjected to 1.4vol%
isoflurane plus 98% O2 (1.5 L/min) inhalation for 1 hour daily and continuing for 5 consecutive days. Then, these rats were subjected to
middle cerebral artery occlusion (MCAO) as focal
cerebral ischemia model. The expression of TWIK-related K+ channel 2 (TREK-2) was analyzed by western blotting and quantitative real-time RT-PCR, and its downstream signaling molecules,
protein kinase C (PKC) alpha,
extracellular signal-regulated kinase 1/2 (ERK1/2), and pERK1/2 were detected by western blotting also. Subsequently, the expression of TREK-2 was regulated by
siRNA transfection in the brain to clarify its role in the neuroprotection of
isoflurane preconditioning. Neurological scores,
infarction volume, and TdT-mediated dUTP Nick-End Labeling (TUNEL) staining were examined to evaluate the outcomes. The impact of TREK-2 on the expression of its downstream signaling molecules was also examined for preliminary analysis of the possible mechanisms.
Isoflurane preconditioning reduced the
infarct volume, inhibited the cell apoptosis, and improved the neurological outcome in rats subjected to MCAO. These effects were parallel with the increase in TREK-2
protein and inhibition of the ERK1/2 phosphorylation. The downregulation of TREK-2 through
siRNA could significantly attenuate the
isoflurane preconditioning-induced
neuroprotective effects.
Isoflurane preconditioning-induced
neuroprotective effects against
ischemia-reperfusion injury are associated with the increase in TREK-2 channel activation. These effects depend on the attenuation of PKC alpha and inhibition of ERK1/2 phosphorylation. Results enrich our understanding on the mechanism of two-pore domain K+ channel in preconditioning-induced tolerance to focal
cerebral ischemia.