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Oxidative Medicine and Cellular Longevity
Volume 2019, Article ID 1896041, 14 pages
https://doi.org/10.1155/2019/1896041
Research Article

Verapamil Attenuated Prediabetic Neuropathy in High-Fat Diet-Fed Mice through Inhibiting TXNIP-Mediated Apoptosis and Inflammation

1Department of Endocrinology, Shenzhen Hospital, Southern Medical University, China
2Department of Huiqiao Building, Nanfang Hospital, Southern Medical University, China
3Department of Endocrinology, Nanfang Hospital, Southern Medical University, China

Correspondence should be addressed to Lingling Xu; moc.361@rotcodgnilgnilux

Received 19 June 2018; Revised 15 October 2018; Accepted 7 November 2018; Published 10 January 2019

Guest Editor: María L. Barreiro Arcos

Copyright © 2019 Lingling Xu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Diabetic neuropathy (DN) is a common and severe complication of diabetes mellitus. There is still a lack of an effective treatment to DN because of its complex pathogenesis. Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of thioredoxin, has been shown to be associated with diabetic retinopathy and nephropathy. Herein, we aim to investigate the role of TXNIP in prediabetic neuropathy and therapeutic potential of verapamil which has been shown to inhibit TXNIP expression. The effects of mediating TXNIP on prediabetic neuropathy and its exact mechanism were performed using high-fat diet- (HFD-) induced diabetic mice and palmitate-treated neurons. Our results showed that TXNIP upregulation is associated with prediabetic neuropathy in HFD-fed mice. TXNIP knockdown improved DN in HFD-induced prediabetic mice. Mechanistically, increased TXNIP in dorsal root ganglion is transferred into the cytoplasm and shuttled to the mitochondria. In cytoplasm, TXNIP binding to TRX1 results in the increased oxidative stress and inflammation. In mitochondria, TXNIP binding to TRX2 induced mitochondria dysfunction and apoptosis. TXNIP isolated from TRX2 then shuttles to the cytoplasm and binds to NLRP3, resulting in further increased TXNIP-NLRP3 complex, which induced the release of IL-1β and the development of inflammation. Thus, apoptosis and inflammation of dorsal root ganglion neuron eventually cause neural dysfunction. In addition, we also showed that verapamil, a known inhibitor of calcium channels, improved prediabetic neuropathy in the HFD-fed mice by inhibiting the upregulation of TXNIP. Our finding suggests that TXNIP might be a potential target for the treatment of neuropathy in prediabetic patients with dyslipidemia.