Ropivacaine Mediates Mitochondrial Dysfunction and Ca2+ Oscillations Attenuation in OPCs Leading to Developmental Spinal Dysmyelination by Inhibiting Akt Signaling

Local anesthetics may induce spinal cord neurotoxicity. Our previous work demonstrated that intrathecal ropivacaine administration causes dysmyelination in the developing spinal cord. This study elucidates the underlying mechanisms. Following intrathecal injection of 2% ropivacaine in postnatal day 7 (PND7) rats, we observed: (1) impaired sensory function evidenced by significantly elevated mechanical and thermal pain thresholds at PND14, PND21, and PND28; and (2) dysmyelination characterized by myelin sheath thinning and increased g-ratio at PND14 and PND21. To explore the molecular mechanism, primary oligodendrocyte precursor cells (OPCs) were isolated and cultured from the spinal cord of neonatal rats. In vitro, ropivacaine dose-dependently suppressed OPCs maturation, manifested by decreased MBP expression, and inhibited spontaneous Ca²⁺ oscillations and Akt activation. These effects were ameliorated by either KCl-induced Ca²⁺ oscillation enhancement or SC79-mediated Akt activation. Notably, the protective effect of SC79 against ropivacaine-induced OPC dysmaturation was abolished by calcium chelation with EGTA, indicating Akt operates upstream of Ca²⁺ oscillations in this pathway. Mechanistically, we identified that ropivacaine-induced mitochondrial dysfunction—evidenced by morphological alterations and impaired respiratory function—stems from Akt suppression and subsequent Ca²⁺ oscillation attenuation. In vivo, SC79-mediated Akt activation mitigated both ropivacaine-induced spinal cord dysmyelination and sensory deficits of hindpaw. Collectively, our study revealed that ropivacaine mediates mitochondrial dysfunction and Ca²⁺ oscillations attenuation in OPCs leading to spinal dysmyelination during development by inhibiting Akt signaling, which may provide a target for preventing the developmental neurotoxicity of local anesthetics.