Bupivacaine reduces GlyT1 expression by potentiating the p-AMPKα/BDNF signalling pathway in spinal astrocytes of rats

Abstract

Bupivacaine, a local anaesthetic, is widely applied in the epidural or subarachnoid space to clinically manage acute and chronic pain. However, the underlying mechanisms are complex and unclear. Glycine transporter 1 (GlyT1) in the spinal cord plays a critical role in various pathologic pain conditions. Therefore, we sought to determine whether bupivacaine exerts its analgesic effect by regulating GlyT1 expression and to determine the underlying mechanisms of regulation. Primary astrocytes prepared from the spinal cord of rats were treated with bupivacaine. The protein levels of GlyT1, brain-derived neurotrophic factor (BDNF) and phosphorylated adenosine 5′-monophosphate (AMP)-activated protein kinase α (p-AMPKα) were measured by western blotting or immunofluorescence. In addition, 7,8-dihydroxyflavone (7,8-DHF, BDNF receptor agonist) and AMPK shRNA were applied to verify the relationship between the regulation of GlyT1 by bupivacaine and the p-AMPKα/BDNF signalling pathway. After treatment with bupivacaine, GlyT1 expression was diminished in a concentration-dependent manner, while the expression of BDNF and p-AMPK was increased. Moreover, 7,8-DHF decreased GlyT1 expression, and AMPK knockdown suppressed the upregulation of BDNF expression by bupivacaine. Finally, we concluded that bupivacaine reduced GlyT1 expression in spinal astrocytes by activating the p-AMPKα/BDNF signalling pathway. These results provide a new mechanism for the analgesic effect of intrathecal bupivacaine in the treatment of acute and chronic pain.

Synergistic Control of Transmitter Turnover at Glycinergic Synapses by GlyT1, GlyT2, and ASC-1

“…Newer studies suggest that GlyT1 is also downregulated in cultured astrocytes by the activation of the protein kinase AMPK in a most likely BDNF-dependent pathway [ 83 ]. In addition to these signaling pathways that regulate the expression of GlyT1 in the plasma membrane, it was shown that there is also a microRNA- (miR) dependent mechanism that regulates the translation of GlyT1 mRNA and thereby, indirectly, the number of GlyT1 molecules within the plasma membrane [ 84 ].…”

NEDD4L-Sp1 ubiquitination inhibits GlyT1 to promote prominent hippocampal neuronal damage and apoptosis, leading to cognitive dysfunction in diabetic rats

“…However, there are still similarities in the regulatory effect of GlyT1 on neuronal synapses and apoptosis. The Glycine transporter protein 1 (GlyT1) inhibitor SSR504734 and the PDE4 inhibitor crotlipram improve hippocampal synaptic plasticity by increasing glycine concentrations in synapses near NMDA receptors [71].Lu et al [72]demonstrated that GlyT1 inhibition not only increases glycine concentrations in synaptic gaps but also decreases the expression of N-methyl-D-aspartate receptors (NMDARs) in synapses, thereby ameliorating neuropathic pain. In addition, persistently increased glycine concentrations near NMDARs may lead to apoptosis.…”

Protective Effect of Ginsenoside Rg5 on Hypoxia/Reoxygenation- Induced H9c2 Cardiomyocytes by Correcting Free Fatty Acids β- oxidation

“…Some studies have indicated that NR4A1 knockdown improves cardiac function [67,71,72]. AMPK is a crucial regulator of fatty acid metabolism that can promote FFA β-oxidation by activating and improving the transcriptional activity of PPAR-α and the phosphorylation of PGC1-α[73,74]. p-AMPK can regulate lipid metabolism through multiple pathways, including increasing fatty acid intake by promoting CD36 and LPL transport[75].…”