Abstract
BACKGROUND: General anesthetics induce neuronal apoptosis in the immature brain. Regional anesthesia using local anesthetics can be an alternative to general anesthesia. Therefore, this study investigated the possible effect of lidocaine on neuronal apoptosis. METHODS: Fifty-one 7-day-old C57BL6 mice were allocated into control (group C), lidocaine (group L), lidocaine plus midazolam (group LM) and isoflurane (group I) groups. Group C received normal saline administration. Groups L and LM were injected with lidocaine (4 mg/kg, subcutaneously) only and the same dose of lidocaine plus midazolam (9 mg/kg, subcutaneously). Group I was exposed to 0.75 vol% isoflurane for 6 h. After 6 h, apoptotic neurodegeneration was assessed using caspase-3 immunostaining and terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining. RESULTS: For the entire brain section, neuronal cells exhibiting caspase-3 activation were observed more frequently in group I than in group C (P < 0.001). In the thalamus, apoptosis of group L was more frequent than that of group C (P < 0.001), but less freqent than that of groups LM and I (P = 0.0075 and P < 0.001, respectively). In the cortex, group I experienced more apoptosis than group L and C (all Ps < 0.001). On TUNEL staining, the difference in apoptosis between the lidocaine and control groups was marginal (P = 0.05). CONCLUSIONS: Lidocaine induced minimal apoptosis in the developing brain compared with isoflurane and lidocaine plus midazolam. However, we cannot fully exclude the possible adverse effect of subcutaneously administered lidocaine on the developing brain.