Neuroprotective effects of glutathione on rainbow trout olfactory receptor neurons during exposure to copper sulfate

In this study glutathione (GSH) provided in vivo neuroprotection for olfactory receptor neurons (ORN) from copper sulfate, a toxicant that accessed the olfactory epithelium directly from the environment into the nasal cavity. When copper sulfate (50 mu g/l) was added to the water in trout holding tanks, ORN with elevated GSH were abundant after 1.5 hr. These later diminished, and membranous material accumulated in the mucociliary complex. After 3 hr, vacuoles formed in the olfactory epithelium and ORN appeared constricted and distorted. This damage was accelerated and potentiated when diethyl maleate was injected to deplete GSH levels. When fish that were pretreated with N-acetylcysteine to augment GSH were exposed to copper sulfate for 3 hr, ORN with elevated GSH remained prominent and histopathological changes were averted. The fact that ORN with elevated GSH preceded histopathological changes in the olfactory epithelium and that depletion of GSH hastened these changes supports the view that elevated GSH localizes in ORN that are challenged by toxic compounds and that GSH provides protection from degenerative changes. (C) 1997 Elsevier Science Inc.