title: A search for residual behavioral effects of trichloroethylene (TCE) in rats exposed as young adults.
abstract: Trichloroethylene (TCE) is an organic solvent with robust acute effects on the nervous system, but poorly documented long-term effects. This study employed a signal detection task (SDT) to assess the persistence of effects of repeated daily inhalation of TCE on sustained attention in rats. Adult male Long-Evans rats inhaled TCE at 0, 1600, or 2400 ppm, 6 h/day for 20 days (n=8/group) and began learning the SDT 3 weeks later. Rats earned food by pressing one retractable response lever in a signal trial and a second lever in a blank (no signal) trial. TCE did not affect acquisition of the response rule or performance of the SDT after the intertrial interval (ITI) was changed from a constant value to a variable one. Increasing the trial presentation rate reduced accuracy equivalently in all groups. Injections of ethanol (0, 0.5, 1.0, 1.5 g/kg ip) and d-amphetamine (0, 0.1, 0.3, 1.0 mg/kg sc) systematically impaired performance as functions of drug dose. d-Amphetamine (1.0 mg/kg) reduced P(hit) more in the 2400-ppm TCE group than in the other groups. All rats required remedial training to learn a reversal of the response contingencies, which TCE did not interfere with. Thus, a history of exposure to TCE did not significantly alter learning or sustained attention in the absence of drugs. Although ethanol did not differentially affect the TCE groups, the effect of d-amphetamine is consistent with solvent-induced changes in dopaminergic functions in the CNS. Calculations indicated power values of 0.5 to 0.8 to detect main effects of TCE for the three primary endpoints.
authors.affiliation: Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, B105-04, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Oshiro
authors.forename: Q Todd
authors.initials: QT
authors.lastname: Krantz
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Bushnell
mesh_terms: D018685:Anesthetics, Inhalation / Q000633:toxicity*; D000818:Animals; D001288:Attention / Q000187:drug effects*; D002492:Central Nervous System Depressants / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects; D003913:Dextroamphetamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D000431:Ethanol / Q000494:pharmacology; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D017603:Signal Detection, Psychological / Q000187:drug effects*; D013997:Time Factors; D014241:Trichloroethylene / Q000633:toxicity*
chemical_list: D018685:Anesthetics, Inhalation; D002492:Central Nervous System Depressants; D000697:Central Nervous System Stimulants; D014241:Trichloroethylene; D000431:Ethanol; D003913:Dextroamphetamine