Prolonged attenuation of acetylcholine‐induced phosphorylation of extracellular signal‐regulated kinase 1/2 following sevoflurane exposure

BACKGROUND: Volatile anaesthetics are known to affect cholinergic receptors. Perturbation of cholinergic signalling can cause cognitive deficits. In this study, we wanted to evaluate acetylcholine-induced intracellular signalling following sevoflurane exposure. METHODS: Pheochromocytoma12 PC12 cells were exposed to 4.6% sevoflurane for 2 h. Subsequently, Western blotting was used to measure acetylcholine-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK) 1/2 and basal Protein kinase B (AKT) phosphorylation. RESULTS: After exposure, acetylcholine-induced ERK 1/2 phosphorylation was reduced to 58 ± 8% [95% confidence interval (CI): 38-77%, P = 0.003] compared with non-exposed controls. At 30 min after the end of sevoflurane administration [at 0.7% sevoflurane (0.102 mM)], ERK 1/2 phosphorylation remained reduced to 57 ± 7% (95% CI: 39-74%, P = 0.001) and was at 120 min [0.02% (0.003 mM] still reduced to 63 ± 10% (95% CI: 37-88%, P = 0.01), compared with control. At 360 min after exposure, acetylcholine-induced ERK 1/2 phosphorylation had recovered to 98 ± 16% (95% CI: 45-152%, P = 0.98) compared with control. In contrast, immediately after sevoflurane exposure, basal AKT phosphorylation was increased by 228 ± 37% (95% CI: 133-324%, P = 0.02) but had returned to control levels at 30 min after exposure, 172 ± 67% (95% CI: 0-356%, P = 0.34). CONCLUSION: Sevoflurane exposure has differential effects on different intracellular signalling pathways. On one hand, we observed a prolonged attenuation of acetylcholine-induced ERK 1/2 phosphorylation that persisted even when sevoflurane concentrations close to detection level. On the other hand, basal AKT phosphorylation was increased twofold during sevoflurane exposure, with a rapid return to baseline levels after exposure. We speculate that the effects on acetylcholine-induced intracellular signalling observed in our in vitro model could be of relevance also for cholinergic signalling in vivo following sevoflurane exposure.