Behavioral and neurochemical effects induced by subchronic exposure to 40 ppm toluene in rats.
Chronic toluene inhalation at concentrations above occupational exposure limits (e.g., 100 ppm; NIOSH) has been repeatedly shown to induce neurotoxic effects. In contrast, although few clinical and experimental data are available on the effects of toluene exposure at concentrations below occupational exposure standards, some of these data may support adverse effects of long-term exposure to low toluene concentrations. To test this hypothesis, we investigated the neurobehavioral and neurochemical effects of 40 ppm inhaled toluene in a rat model of 16-week subchronic exposure, examining locomotor and rearing activities; adaptation/sensitization to narcosis produced by acute exposure to toluene at high concentration; and tyrosine hydroxylase and tryptophan hydroxylase activities, and dopamine (DA) and serotonin (5-HT) turnovers in the caudate-putamen, nucleus accumbens, hippocampus, prefrontal cortex, and cerebellum. Our results mainly show that subchronic exposure to 40 ppm toluene significantly resulted in a sensitization to toluene-induced narcosis, a decrease in rearing activity, and alterations in DA and 5-HT transmissions. This demonstrates that subchronic toluene exposure at a low concentration may lead to adverse changes in neurobehavioral and neurochemical functioning, and further questions in a public health perspective the actual neurotoxic potential of toluene and other organic compounds, because deficits in functioning are generally viewed as precursors of more serious adverse effects.
Berenguer
Patrick
P
UMR CNRS 6551, Mort Neuronale, Neuroprotection et Neurotransmission, Centre CYCERON, Boulevard Henri Becquerel, BP 5229, Caen Cedex 14074, France.
Soulage
Christophe
C
Perrin
David
D
Pequignot
Jean-Marc
JM
Abraini
Jacques H
JH
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D004781:Environmental Exposure; D005260:Female; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013997:Time Factors; D014050:Toluene / Q000008:administration & dosage*
D012701:Serotonin; D014050:Toluene; D004298:Dopamine