Odor detection in rats with 3-methylindole-induced reduction of sensory input

Rats were tested on odor-detection tasks after treatment with 400 mg/kg of 3-methylindole. As revealed by anterograde transport of horseradish peroxid ase from the olfactory epithelium to the olfactory bulb glomeruli, treatmen t produced a severe (>97%) loss in sensory input relative to untreated cont rols. In almost all cases, only glomeruli in a restricted ventromedial segm ent of the bulb contained control levels of reaction product. In Experiment 1, five of nine experimental rats were anosmic or severely hyposmic, but t he remaining four rats were able to detect amyl acetate vapor. In Experimen t 2, four of seven experimental rats were anosmic, but the remaining three were able to detect each of four different odors. Among all experimental ra ts, those that were anosmic bad significantly fewer glomeruli with dense an terograde transport than did those that could smell. Among rats that could smell, performance accuracy was related to the number of glomeruli with rea ction product. (C) 1998 Elsevier Science Inc.