Myelin structure is unaltered in chemotherapy-induced peripheral neuropathy

PurposeAlterations in mRNA for myelin proteins are reported in animal models of chemotherapy-induced peripheral neuropathies (CIPN); however, ultrastructural changes in aldehyde-fixed and plastic-embedded myelin are not evident by electron microscopy. Therefore, we used X-ray diffraction (XRD) to investigate more subtle changes in myelin sheath structure from unfixed nerves.Experimental designWe used in vivo chronic animal models of CIPN in female Wistar rats, administering cisplatin (CDDP 2 mg/kg, i.p. twice/week), paclitaxel (PT 10 mg/kg, i.v. once/week) or bortezomib (0.20 mg/kg, i.v. three times/week) over a total period of 4 weeks. Animal weights were monitored, and tail nerve conduction velocity (NCV) was determined at the end of the treatments to assess the occurrence of peripheral neuropathy. Sciatic nerves were collected and the myelin structure was analyzed using electron microscopy (EM) and XRD.ResultsAll the rats treated with the chemotherapy agents developed peripheral neuropathy, as indicated by a decrease in NCV values; however, light and electron microscopy indicated no severe pathological alterations of the myelin morphology. XRD also did not demonstrate significant differences between sciatic nerves in treated vs. control rats with respect to myelin period, relative amount of myelin, membrane structure, and regularity of membrane packing.ConclusionsThese results indicate that experimental peripheral neuropathy caused by CDDP, PT, and bortezomib—which are among the most widely used chemotherapy agents—does not significantly affect the structure of internodal myelin in peripheral nerve.

► Chemotherapy-induced peripheral neuropathy (CIPN) may affect internodal myelin.
► We examine sciatic nerves in rat models of three commonly used anticancer agents.
► Electron microscopy shows no changes in morphology of fixed nerves in CIPN models.
► X-ray diffraction of unfixed nerves reveals unaltered myelin structure and amount.
► Internodal myelin is not the target of CIPN at the structural resolution used here.