Effect of endoplasmic reticulum stress in the occurrence of Methotrexate-related neurotoxicity and cognitive impairment / 中华实用儿科临床杂志

ABSTRACT

Objective To investigate the relationship between Methotrexate (MTX) and its cognitive dysfunction,and to explore the possible mechanism of neurotoxicity induced by MTX.Methods Thirty healthy male SD rats weighting 180-220 g were divided into 3 groups using random number tablecontrol group,60 mg/kg MTX (MTX60) group and 100 mg/kg MTX (MTXt00) group,with 10 rats in each group.The rats in MTX60 group,MTX100 group received 60 mg/kg MTX and 100 mg/kg MTX,respectively.The rats in control group accepted the same volume of 9 g/L saline injection as MTX group.Spatial memory of rats was evaluated by using Morris water maze test at different time points after pretreatment with MTX.After the Morris water maze test,the hippocampus were harvested and the expressions of C/EBP homologous protein (CHOP),cysteinyl aspartate specific proteinase 12(caspase-12) and cleave cysteinyl aspartate specific proteinase 3 (cleaved caspase-3) were detected by using Western blot.Meanwhile,cell apoptosis and pathological change of hippocampal neurons were detected by terminal dexynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) assay and HE staining respectively.Results In the Morris water maze test,the time in platform quadrant of rats in MTX60 group and MTX100 group was shorter than that of rats in control group during probe training [(27.30 ±3.98) s and (21.63 ±4.22) s vs (33.30 ±6.31) s,F =13.94,P ＜0.05],and the time in target quadrant of MTX100 group was shorter than that of MTX60 group (P ＜ 0.05).Compared with the control group,there were degenerated neurons in hippocampus cornu ammonis 1 (CA1) area in MTX60 group and MTX100 group.The number of TUNEL-positive cells of the hippocampus CA1 area increased significantly in MTX60 group and MTX100 group rats [(4.72 ±0.12)％ and (9.12±0.12)％ vs (1.11 ±0.49)％,F=95.272,P ＜0.05],and the TUNEL-positive cells of rats in MTX100 group were more than those of MTX60 group (P ＜ 0.05).The expressions of CHOP,caspase-12 and cleaved caspase-3 also increased compared with the control group (CHOP2.98 ±0.31 and 4.15 ±0.61 vs 0.38 ±0.12,F =232.74,P ＜ 0.05;caspase-120.33 ±0.04 and 0.43 ±0.06 vs 0.14 ±0.02,F =120.70,P ＜ 0.05;cleaved caspase-30.35 ± 0.04 and 0.44 ± 0.06 vs 0.05 ± 0.03,F =198.64,P ＜ 0.05),and the protein expression levels of rats in MTX100 group were higher than MTX60 group (all P ＜ 0.05).Conclusions MTX can induce cognitive impairment in rats,and endoplasmic reticulum stress mediated hippocampal neurons apoptosis may play an important role in the mechanism of MTX-induced cognitive impairment in rats.