Wang Qi, Li Yuan, Tan Hong, Wang Yingwei
Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China.
Front Mol Neurosci. 2022 Apr 8;15:873658. doi: 10.3389/fnmol.2022.873658. eCollection 2022.
General anesthetics are capable of inducing neuronal apoptosis during the rapid synaptogenesis of immature mammalian brains. In this vulnerable time window, physiological apoptosis also occurs to eliminate excess and inappropriately integrated neurons. We previously showed that physiological and ketamine-induced apoptosis in mouse primary somatosensory cortex (S1) followed similar developmental patterns. However, since sevoflurane is more widely used in pediatric anesthesia, and targets mainly on different receptors, as compared with ketamine, it is important to determine whether sevoflurane-induced apoptosis also follows similar developmental patterns as physiological apoptosis or not. Mice at postnatal days 5 (P5) and P9 were anesthetized with 1.5% sevoflurane for 4 h, and the apoptotic neurons in S1 were quantitated by immunohistochemistry. The results showed that sevoflurane raised the levels of apoptosis in S1 without interfering with the developmental patterns of physiological apoptosis. The cells more vulnerable to both physiological and sevoflurane-induced apoptosis shifted from layer V pyramidal neurons at P5 to layers II-IV GABAergic neurons by P9. The magnitude of both sevoflurane-induced and physiological apoptosis was more attenuated at P9 than P5. To determine whether the Akt-FoxO1-PUMA pathway contributes to the developmental decrease in magnitude of both physiological and sevoflurane-induced apoptosis, Western blot was used to measure the levels of related proteins in S1 of P5 and P9 mice. We observed higher levels of antiapoptotic phosphorylated Akt (p-Akt) and phosphorylated FoxO1 (p-FoxO1), and lower levels of the downstream proapoptotic factor PUMA in control and anesthetized mice at P9 than P5. In addition, the Akt-FoxO1-PUMA pathway may also be responsible for sevoflurane-induced apoptosis. Together, these results suggest that magnitude, lamination pattern and cell-type specificity to sevoflurane-induced apoptosis are age-dependent and follow physiological apoptosis pattern. Moreover, The Akt-FoxO1-PUMA pathway may mediate the developmental decreases in magnitude of both physiological and sevoflurane-induced apoptosis in neonatal mouse S1.
全身麻醉药能够在未成熟哺乳动物脑快速突触形成期间诱导神经元凋亡。在这个易损的时间窗内，生理性凋亡也会发生以清除多余的和整合不当的神经元。我们之前表明，小鼠初级体感皮层（S1）中生理性和氯胺酮诱导的凋亡遵循相似的发育模式。然而，由于七氟醚在儿科麻醉中应用更为广泛，并且与氯胺酮相比主要作用于不同的受体，因此确定七氟醚诱导的凋亡是否也遵循与生理性凋亡相似的发育模式很重要。出生后第5天（P5）和第9天（P9）的小鼠用1.5%七氟醚麻醉4小时，通过免疫组织化学对S1中的凋亡神经元进行定量。结果表明，七氟醚提高了S1中的凋亡水平，但不干扰生理性凋亡的发育模式。对生理性和七氟醚诱导的凋亡均更敏感的细胞从P5时的V层锥体神经元转变为P9时的II-IV层γ-氨基丁酸能神经元。七氟醚诱导的凋亡和生理性凋亡的程度在P9时比P5时更弱。为了确定Akt-FoxO1-PUMA通路是否导致生理性和七氟醚诱导的凋亡程度在发育过程中的降低，采用蛋白质免疫印迹法检测P5和P9小鼠S1中相关蛋白的水平。我们观察到，与P5相比，P9时对照和麻醉小鼠中抗凋亡的磷酸化Akt（p-Akt）和磷酸化FoxO1（p-FoxO1）水平更高，下游促凋亡因子PUMA水平更低。此外，Akt-FoxO1-PUMA通路可能也参与七氟醚诱导的凋亡。总之，这些结果表明，七氟醚诱导凋亡的程度、分层模式和细胞类型特异性具有年龄依赖性，并遵循生理性凋亡模式。此外，Akt-FoxO1-PUMA通路可能介导新生小鼠S1中生理性和七氟醚诱导的凋亡程度在发育过程中的降低。
