title: Acute exposures to p-xylene and toluene alter visual information processing.
abstract: Long-Evans hooded rats were exposed to single doses of toluene (PO) at 0, 250, 500 and 1000 mg/kg, to p-xylene (PO) at 0, 125, 250, 500, 1000 and 2000 mg/kg, and to inhalation of p-xylene for 4 hr at 0, 800 or 1600 ppm. The functional integrity of the visual system was evaluated using flash-evoked potentials (FEPs). The data indicated a significant depression in amplitude of FEP peak N3 at 250 mg/kg and higher dosages of toluene and p-xylene. A similar depression in peak N3 amplitude was observed following inhalation exposure to 1600 ppm p-xylene. The effects produced by oral administration of 500 mg/kg p-xylene or toluene lasted at least 8 hr, while the effect of inhaled p-xylene dissipated within 75 min of removal from the exposure. FEP peak N3 is presumed to be related to arousal, such that increases in arousal from a relaxed state should decrease amplitude. Rats administered amphetamine in dosages of 0.6, 1.2 and 2.5 mg/kg (known to increase arousal) also had reduced N3 amplitude. The effects of p-xylene and toluene on FEPs, while indicative of altered processing of visual information, may be secondary to changes in arousal or excitability.
authors.affiliation: Neurophysiology Branch, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711.
authors.forename: R S
authors.initials: RS
authors.lastname: Dyer
authors.forename: M S
authors.initials: MS
authors.lastname: Bercegeay
authors.forename: L M
authors.initials: LM
authors.lastname: Mayo
mesh_terms: D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005074:Evoked Potentials, Visual / Q000187:drug effects; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D014050:Toluene / Q000633:toxicity*; D014796:Visual Perception / Q000187:drug effects*; D014992:Xylenes / Q000633:toxicity*
chemical_list: D014992:Xylenes; D014050:Toluene; C031286:4-xylene; D000661:Amphetamine