Calpain‐2 plays a pivotal role in the inhibitory effects of propofol against TNF‐α‐induced autophagy in mouse hippocampal neurons

Abstract

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.

The Effects of Intraoperative Hypothermia on Postoperative Cognitive Function in the Rat Hippocampus and Its Possible Mechanisms

“…Although various pathological factors have been demonstrated to be responsible for POCD, evidence from experimental studies revealed that synaptic dysfunction in the central nervous system, particularly in the hippocampus, may be involved in POCD’s progression [ 47 , 48 ]. Furthermore, synaptic dysfunction is associated with the abnormal expression of proteins required for synaptic function [ 49 , 50 ]. Therefore, we measured the expression levels of synaptic plasticity-associated proteins, including Arc, CREB, p-CREB (S133), AMPAR1, and p-AMPAR1 (S831) by Western blotting to further explore the underlying molecular mechanism.…”

The Effects of Propofol on Hypoxia- and TNF-α-Mediated Brain-Derived Neurotrophic Factor/Tyrosine Kinase Receptor B Pathway Dysregulation in Primary Rat Hippocampal Neurons and Astrocytes

“…Nowadays, the neuro-protective property of propofol in the CNS and the underlying mechanism are of great interests. A large amount of in vitro studies revealed that propofol may improve BBB function [21], protect neuron apoptosis [18] and autophagy [17], and maintain microglia function [32]. In addition, animal studies demonstrated that propofol may improve brain function in rats with ischemia-reperfusion injury [33] and may ameliorate neuroin ammatory injury in rats [34,35].…”

“…Apart from its multiple anesthetic advantages, it has been reported to possess anti-oxidative and anti-in ammatory effects [14,15] as well as neuro-protective properties [16]. A number of in vitro studies revealed that propofol may protect mouse hippocampal neurons from in ammation-induced autophagy [17] and from in ammationand hypoxia-as well as oxidative stress-induced apoptosis [18][19][20]. In addition, propofol may protect hypoxia-and in ammation-impaired integrity of blood-brain barrier (BBB) in the in vitro model [17,[21][22][23].…”

The effect of propofol on hypoxia‐ and TNF‐α‐mediated BDNF/TrkB pathway dysregulation in primary rat hippocampal neurons

“…To examine the effect of propofol, cells were treated with different concentrations (1, 5, 10, 25, 50, and 100 μM) of propofol (Sigma‐Aldrich, St. Louis, MO, USA) or its solvent, 0.1% dimethyl sulfoxide (DMSO) for 1h, and then exposed to hypoxic or inflammation condition. These treatment conditions have been repeatedly used to induce vicious effects in hippocampal neurons 17,21 . We intended to identify the effect of hypoxia, inflammation, and propofol on the production of BDNF and the expression/truncation/phosphorylation of TrkB in hippocampal neurons and astrocytes.…”

“…Apart from its multiple anesthetic advantages, it has been reported to possess anti‐oxidative and anti‐inflammatory effect 14,15 as well as neuroprotective property 16 . A number of in vitro studies revealed that propofol may protect mouse hippocampal neurons from autophagy induced by inflammation 17 and from apoptosis induced by inflammation, hypoxia, or oxidative stress 18–20 . In addition, in vitro models indicated propofol may protect the integrity of blood‐brain barrier (BBB) from impairment by hypoxia and inflammation 17,21–23 .…”