Hyperglycemia magnifies bupivacaine‐induced cell apoptosis triggered by mitochondria dysfunction and endoplasmic reticulum stress

Abstract

Nerve cell injury associated with apoptosis plays an important role in the development of diabetic peripheral neuropathy (DPN). However, it remains unclear whether preexisting or potential neurocyte damage induced by hyperglycemia increases sensitivity to local anesthetics. SH-SY5Y cells were pretreated with a high concentration of glucose in vitro, to imitate DPN prior to administration of bupivacaine or placebo. Cell viability and apoptosis were investigated with a CCK-8 assay and flow cytometry, respectively. In addition, mitochondrial membrane potential, reactive oxygen species (ROS), mitochondrially generated ROS, and activity of mitochondrial complexes I and III were studied to explore the molecular mechanism of bupivacaine-induced mitochondrial injury. Grp78 and caspase-12 expression were measured by qRT-PCR and Western blot, representing endoplasmic reticulum (ER) stress. Cell structure was also assessed via transmission electron microscopy. Incubation with bupivacaine decreased the activity of mitochondrial complexes I and III; increased ROS production at cell and mitochondrial levels, mitochondrial potential depolarization, and Grp78 and caspase-12 expression at both transcription and translation levels; and affected cell structure, which could be enhanced by glucose pretreatment. These findings indicate that mitochondrial dysfunction and ER stress related to ROS are involved in bupivacaine-induced apoptosis and may be enhanced by glucose administration.

CHOP/ORP150 Ratio in Endoplasmic Reticulum Stress: A New Mechanism for Diabetic Peripheral Neuropathy

“…Considering the fact that ER stress plays a critical role in nerve injury, we decided to continue our investigation from this perspective. To this end, we first determined if the redox state in sciatic nerves was adversely altered in diabetes, as oxidative stress is a key factor for ER stress [10,11,12]. As illustrated in Figure 3A, the level of basal H 2 O 2 production in sciatic nerves was relative low in control animals, but it was robustly increased in PD rats and slightly increased in ED rats (Fig.…”

“…ER stress is an important biochemical mechanism for protein quality control and cell death as well [10,11,12,46]. A number of signalling pathways are activated during ER stress, which either mediate survival or apoptotic signal.…”

“…Upregulation and activation of ER stress proteins is an adaptive mechanism for protein quality control in response to adverse stimuli, but in the face of inducing metabolic disturbances, deregulation of gene expression, and apoptotic cell death after a prolonged period. The apoptotic mechanism is initiated when functions of the ER are severely impaired, to protect the organism by eliminating the damaged cells, with at least three apoptosis pathways being involved in this process [10,11,12]. The first of these three among the diverse array of proteins induced by ER stress is transcriptional activation of the gene for CCAAT-enhancer-binding protein homologous protein (CHOP) that mediates apoptosis.…”

“…Vulnerability of neuronal cells to environmental stress contributes to pathogenesis of neurodegenerative disorders. Recently, a growing body of evidence suggested that endoplasmic reticulum (ER) stress plays a key role in the pathogenesis of diabetes mellitus and the associated diabetic peripheral neuropathy as well [10,11,12]. ER stress is a condition resulting from abnormal folding of newly synthesized proteins in response to a variety of adverse stimulation, particularly production and accumulation of ROS.…”

Activation of p47phox as a Mechanism of Bupivacaine‐Induced Burst Production of Reactive Oxygen Species and Neural Toxicity

“…Studies in mouse N2a cells have shown that bupivacaine induced burst production of reactive oxygen species (ROS), leakage of lactate dehydrogenase (LDH), decline mitochondrial potential, nuclear condensation, and cell apoptosis that were associated with inhibition of the AKT/PI3K pathway [9, 10]. Our previous study also showed that bupivacaine induced human SH-SY5Y cell ROS burst, DNA damage, mitochondrial dysfunction, ER stress (endoplasmic reticulum stress) [5, 11, 12]. These pathways were all involved with ROS burst.…”