Effect on the peripheral nervous system of systemically administered dimethylsulfoxide in the rat: a neurophysiological and pathological study

The issue of dimethylsulfoxide (DMSO) neurotoxicity is an important one, gi ven its wide use in experimental toxicology as a solvent for hydrophobic su bstances. We examined the effect of the intraperitoneal administration of d ifferent DMSO solutions (1.8-7.2%) on the peripheral nervous system of Wist er rats treated for 10 consecutive days and followed-up for an additional 4 5 days. DMSO administration induced a dose-dependent reduction in nerve con duction velocity, with complete recovery occurring in the follow-up. No str uctural changes were found in the sciatic nerve at 1.8%, and 3.6% DMSO conc entrations, suggesting that the mechanism of action of DMSO involves a func tional impairment (i.e. conduction block) similar to that already described for this substance in isolated systems. However, when DMSO was administere d at the 7.2% concentration, evident structural changes were observed in th e sciatic nerve, with myelin disruption and uncompacted myelin lamalle. The neurophysiological and pathological changes observed in our study are seve re enough to merit careful consideration in the course of experimental stud ies involving DMSO as a solvent for drugs which are under evaluation For th eir potential neurotoxicity. (C) 2000 Elsevier Science Ireland Ltd. All rig hts reserved.