A search for residual behavioral effects of trichloroethylene (TCE) in rats exposed as young adults.
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.
Oshiro
Wendy M
WM
Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, B105-04, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
Krantz
Q Todd
QT
Bushnell
Philip J
PJ
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*
D018685:Anesthetics, Inhalation; D002492:Central Nervous System Depressants; D000697:Central Nervous System Stimulants; D014241:Trichloroethylene; D000431:Ethanol; D003913:Dextroamphetamine