Calpains are calcium‐dependent proteases and play critical roles in neuronal autophagy induced by inflammation. Propofol has been reported to exert anti‐inflammatory effects in neurons. We aimed to identify whether and how propofol‐modulated calpain activity and neuron autophagy in response to tumour necrosis factor‐α (TNF‐α). Mouse hippocampal neurons were pre‐treated with propofol and exposed to TNF‐α. Autophagy was evaluated by fluorescent autophagy assay and by measuring LC3I and LC3II expression. Intracellular calcium concentration was measured by fluorescent assay. Calpain activation was measured by calpain activity assay. The protein expression of intracellular signalling molecules was detected by Western blot analysis. Compared with untreated control neurons, 40 ng/mL TNF‐α treatment for 2 hours induced neuron autophagy, which was attenuated by 25 μmol/L propofol. TNF‐α induced intracellular calcium accumulation, the phosphorylation of calcium/calmodulin‐dependent protein kinase II (CAMK II) and calpain‐2, calpain activation and lysosomal cathepsin B release as well as tyrosine kinase receptor B (TrkB) truncation. These effects were alleviated by propofol, calcium chelator, CAMK II inhibitor, calpain‐2 inhibitor, calpain‐2 siRNA transfection and N‐Methyl‐d ‐aspartic acid (NMDA) receptor antagonist. Propofol, via NMDA receptor, inhibited TNF‐α‐mediated hippocampal neuron autophagy. The mechanism may involve calcium and calcium‐dependent signalling pathway, especially CAMK II and calpain‐2.

中文翻译：

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Calpain-2 在丙泊酚对 TNF-α 诱导的小鼠海马神经元自噬的抑制作用中起关键作用。

钙蛋白酶是钙依赖性蛋白酶，在炎症诱导的神经元自噬中起关键作用。据报道，丙泊酚对神经元具有抗炎作用。我们旨在确定丙泊酚是否以及如何调节钙蛋白酶活性和神经元自噬以响应肿瘤坏死因子-α（TNF-α）。小鼠海马神经元用丙泊酚预处理并暴露于 TNF-α。自噬通过荧光自噬测定和测量 LC3I 和 LC3II 表达来评估。通过荧光测定法测量细胞内钙浓度。钙蛋白酶活化通过钙蛋白酶活性测定来测量。通过蛋白质印迹分析检测细胞内信号分子的蛋白质表达。与未处理的对照神经元相比，40 ng/mL TNF-α 处理 2 小时诱导神经元自噬，25 μmol/L 丙泊酚减弱。TNF-α 诱导细胞内钙积累、钙/钙调蛋白依赖性蛋白激酶 II (CAMK II) 和钙蛋白酶-2 的磷酸化、钙蛋白酶激活和溶酶体组织蛋白酶 B 释放以及酪氨酸激酶受体 B (TrkB) 截断。丙泊酚、钙螯合剂、CAMK II 抑制剂、钙蛋白酶-2 抑制剂、钙蛋白酶-2 siRNA 转染和 N-甲基-d-天冬氨酸（NMDA）受体拮抗剂。丙泊酚通过 NMDA 受体抑制 TNF-α 介导的海马神经元自噬。该机制可能涉及钙和钙依赖性信号通路，尤其是CAMK II和钙蛋白酶2。