Western diet‐induced insulin resistance impairs recovery after experimental spinal cord injury
Authors: Kim Ha Neui , Yoon Hyesook , Langley Monica , Kleppe Laurel , Scarisbrick Isobel Ann 
Published: June 2021

The cardinal signs of systemic metabolic dysfunction, including insulin resistance, hypertension and a systemic pro‐inflammatory state are risk factors for the development of cardiovascular disease, type 2 diabetes, and neurodegenerative conditions, but there is limited information regarding the impact on recovery after spinal cord injury (SCI). To address this gap, we investigated the impact of systemic insulin resistance generated by consumption of a diet high in fat and sucrose, often referred to as a Western Diet, on neuropathophysiological outcomes in a murine compression model of incomplete SCI. Ten‐week‐old female C57BL6 mice were provided a regular diet (RD) or a diet high in fat and sucrose (HFHS) for 7 weeks prior to experimental compression SCI.Mice consuming a Western Diet showed signs of systemic insulin resistance such as evaluated blood glucose. In addition, signs of insulin resistance within the substance of the spinal cord were also observed, including reductions in the abundance of insulin‐like growth factor 1 receptor (IGF‐1R). Impairments in motor recovery evaluated by BMS score and subscore were present in mice consuming HFHS at 14 and 30 days post injury (dpi). Consumption of a diet rich in fat and sucrose also impaired the mean maximal angle achieved on the inclined plane test and resulted in significant impairments in bladder release. Immunochemical analysis of the spinal cord revealed a number of differences in markers of neural injury between the two groups. First, mice consuming HFHS exhibited significant increases in astrogliosis measured by glial fibrillary acidic protein (GFAP) prior to injury, compared to mice consuming a RD. In fact, the prominent increases in GFAP observed in the intact spinal cord of mice consuming HFHS were equivalent to those observed after SCI in mice consuming a regular chow. In the subacute period, markers of microglial/monocyte activation were elevated in all mice with SCI; however, the increase was substantially greater in the spinal cords of mice consuming HFHS. The spinal cord white matter of mice consuming HFHS also showed reductions in the number of oligodendrocyte progenitor and mature myelinating cells prior to SCI and HFHS‐associated reductions in myelin producing cells persisted at 14 and 30 dpi. In addition, loss of serotonergic axons in the spinal cord after SCI was exacerbated in mice consuming HFHS. Growth associated protein 43 (GAP43), a marker of axonal growth cones was elevated after SCI in the spinal cords of mice consuming a RD or a HFHS diet; however, the magnitude of the increase in growth cones was severely impaired in mice consuming HFHS.These findings suggest that consumption of a Western Diet increases the risk of insulin resistance within the central nervous system and impairs neurobehavioral recovery after SCI. These studies highlight insulin resistance as a new mechanism that limits nervous system repair after SCI and as a potential target for intervention to improve functional outcomes.Support or Funding InformationNIH R01 NS052741 and The Minnesota State SCI and TBI Research Grant Program.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.