Role of NORAD in ketamine-induced neurotoxicity in mouse hippocampal neurons: association with endoplasmic reticulum stress / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the role of long non-coding RNA (lncRNA) NORAD in ketamine-induced neurotoxicity in mouse hippocampal neurons and the relationship with endoplasmic reticulum stress.Methods:Primary mouse hippocampal neurons were isolated and cultured and then divided into 5 groups ( n=36 each) using a random number table method: control group (group C), ketamine group (group K), ketamine+ pcDNA3.1-NORAD plasmid group (group K+ NORAD), ketamine+ control plasmid group (group K+ NC), and ketamine+ NORAD+ tunicamycin group (group K+ NORAD+ TM). Group C was cultured with normal medium for 24 h. Group K was cultured with 40 μmol/L ketamine for 24 h. Group K+ NORAD was transfected with pcDNA3.1-NORAD overexpressing plasmid for 48 h, followed by treatment with 40 μmol/L ketamine for 24 h. Group K+ NC was transfected with pcDNA3.1 (+ ) plasmid for 48 h, followed by treatment with 40 μmol/L ketamine for 24 h. Group K+ NORAD+ TM was transfected with pcDNA3.1-NORAD overexpressing plasmid, 24 h later endoplasmic reticulum stress activator tunicamycin 1 μg/ml was added and the neurons were cultured for 24 h, and then ketamine 40 μmol/L was added and the neurons were cultured for another 24 h. Cell viability was detected by CCK-8 assay. The amount of lactate dehydrogenase (LDH) released was analyzed. Cell apoptosis was determined by TUNEL and flow cytometry methods. The NORAD expression was detected by real-time polymerase chain reaction. The expression of endoplasmic reticulum stress-related proteins protein kinase R-like ER kinase (PERK), phosphorylated PERK (p-PERK) and C/EBP homologous protein (CHOP) was detected by Western blot. Results:Compared with group C, the cell viability was significantly decreased, the amount of LDH released, percentage of apoptotic neurons and apoptosis rate were increased, NORAD expression was down-regulated, CHOP expression was up-regulated, and p-PERK/PERK was increased in group K ( P<0.05). Compared with group K, the cell viability was significantly increased, the amount of LDH released, percentage of apoptotic neurons and apoptosis rate were decreased, NORAD expression was up-regulated, CHOP expression was down-regulated, and p-PERK/PERK was decreased in group K+ NORAD ( P<0.05), and no significant change was found in the parameters mentioned above in group K+ NC ( P>0.05). Compared with group K+ NORAD, the cell viability was significantly decreased, the amount of LDH released, percentage of apoptotic neurons and apoptosis rate were increased, CHOP expression was up-regulated, and p-PERK/PERK was increased ( P<0.05), and no significant change was found in the NORAD expression in group K+ NORAD+ TM ( P>0.05). Conclusions:Over-expressed NORAD can alleviate ketamine-induced neurotoxicity in mouse hippocampal neurons via inhibition of the endoplasmic reticulum stress.