Thioredoxin-1 Protects Spinal Cord from Demyelination Induced by Methamphetamine through Suppressing Endoplasmic Reticulum Stress and Inflammation
Methamphetamine (METH) is a psychostimulant abused around the world. Emerging evidence indicates that METH causes brain damage. However, there are very few reports on METH-induced demyelination. Thioredoxin-1 (Trx-1) is a redox regulating protein and plays the roles in protecting neurons from various stresses. However, whether Trx-1 resists demyelination induced by METH has not been reported. In this study, we found that METH-induced thin myelin sheaths in spinal cord, whereas Trx-1 overexpression transgenic (TG) mice restored the myelin sheaths thickness. The expressions of myelin-associated glycoprotein, myelin basic protein, and cyclin-dependent kinase 5 were decreased by METH, whereas these alterations were blocked in Trx-1 TG mice. The expressions of procaspase-12 and procaspase-3 were decreased by METH, the expression of calpain1 was increased by METH, whereas the alterations were suppressed in Trx-1 TG mice. As same as, the expressions of the extracellular signal-regulated kinase, nuclear factor κB, tumor necrosis factor-alpha, and interleukin-1beta were induced by METH, which were suppressed in Trx-1 TG mice. These data suggest that Trx-1 may play a critical role in resisting the METH-mediated demyelination in spinal cord through regulating endoplasmic reticulum stress and inflammation pathways.Methamphetamine was obtained from Yunnan Province Public Security Department and dissolved in sterile water. Anti-mouse Trx-1 rabbit polyclonal antibody (14999-1-AP; 1:1,000) was purchased from ProteinTech (Wuhan, China). The antibodies MAG (sc-15324; 1:1,000), MBP (sc-376995; 1:1,000), procaspase-12 (sc-5627, 1:1,000), calpain1 (sc-13990; 1:1,000), phosphorylation extracellular signal-regulated kinase (p-ERK, sc-7383; 1:1,000), extracellular signal-regulated kinase (ERK, sc-94; 1:1,000), and β-actin (sc-47778; 1:1,000) were purchased from Santa Cruz Bio Technology (Santa Cruz, CA, USA). The antibodies procaspase-3 (19677-1-AP, 1:2,000) and nuclear factor κB (NF-κB) (10745-1-AP, 1:2,000) were purchased from Proteintech Group (Proteintech Group, Inc., Wuhan, Hubei, China). The antibody CDK5 (Ab-40773; 1:2,000) was purchased from Abcam (Abcam plc, Cambridge, UK). qRT-PCR primers [β-actin, interleukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α)] were purchased from Sangon Biotech Co., Ltd. (Shanghai, China).Associative learning between contextual cues and the rewarding effects of abused substances can result in CPP, a behavior observed in rodents (15). In this study, we determined METH-induced rewarding effect by using CPP in control group mice. The experimental schedule was described in Figure
1A. The result showed that the CPP was blocked in TG mice (Figure
1B). Two-way ANOVA showed a significant mice × drug interaction (F1, 20 = 22.59, P < 0.001) and significant influence of drug (F1, 20 = 34.07, P < 0.001) and mice (F1, 20 = 26.00, P < 0.001). Bonferroni post hoc test revealed significant difference between the control and METH group (P < 0.001), but no significant difference in TG mice and TG mice + METH group (P > 0.05).This work is supported by National Natural Science Foundation of China (grant numbers 81660222 and U1202227). The authors thank Dr. Zhizhou Shi and Henqian Wu of the Key Laboratory of Medical Neurobiology, Kunming University of Science and Technology for technical assistance with data collection.