The Effects of Lavendustin‐A on Peripheral Nerve Degeneration in Hyperglycemic Danio rerio

Abstract

Diabetic peripheral neuropathy (DPN) results in degenerating peripheral nerves and affects over 50% of people with diabetes. Despite its high prevalence, DPN’s molecular pathways remain unknown, limiting treatment to pain management. The Clark lab has characterized two novel models of hyperglycemia in zebrafish in which DPN‐like phenotypes are recapitulated, including demyelination. In an attempt to elucidate the unknown molecular mechanisms of DPN, candidate small molecule drugs are currently being tested to accentuate or attenuate neurodegeneration. Lavendustin‐A, an EGFR tyrosine kinase inhibitor (TKI), was hypothesized to have a neuroprotective role, as overactivation of EGFR in hyperglycemic environments is associated with fibrosis and the inhibition of regeneration in various tissue types. Tg(mbp:gfpcaax) larval zebrafish were incubated in egg water (control 1) or 120mM glucose solution (control 2 and treatment) starting five days post‐fertilization (dpf) until 10dpf. From 10‐12dpf, control 1 remained in egg water + 1% DMSO, control 2 remained in glucose solution + 1% DMSO, and the treatment group remained in glucose solution + 1% DMSO + 65.5µM Lavendustin‐A. 12dpf, lateral images of myelinated (MBP+) peripheral motor nerves were taken on an EVOS imaging system. Fiji (NIH) software was used to measure the length and fluorescent intensity of the myelinated nerves. Both nerve length (*p=0.025) and MBP fluorescent intensity (**p=0.0013) were significantly greater in the treatment group compared to the hyperglycemic fish (control 2), and no significant difference was observed between the treatment group and control 1. To determine if function was impacted, a touch‐response assay was conducted before (10dpf) and after (12dpf) drug treatment. Escape response was significantly impaired in hyperglycemic fish (treatment and control 2) at 10dpf (***p=0.0007) and significantly improved in the treatment group by 12dpf (***p=0.0003), yet did not fully recover, as there was still a significant difference between the treatment group and control 1 (**p=0.0017). Our data suggests a possible role of EGFR in hyperglycemia‐induced neurodegeneration, getting us one step closer to identifying potential therapeutics for clinical application.