NEUROBEHAVIORAL AND NEUROCHEMICAL INVESTIGATION OF TOLUENE, MONOCHLOROBENZENE, AND STYRENE INHALATION IN THE RAT
Abstract
Inhalation exposures to toluene, monochlorobenzene, and styrene were conducted in an inhalation system designed for neurologic/behavior toxicologic investigation of gases and vapors. Neurobehavioral effects were determined with animals trained on a fixed interval (FI-120 sec) schedule. Behavioral measures were response rate, subinterval response rate, and quarter life with 6 replications per determination, whereby each animal served as its own control. Behavioral effects were determined following 1, 4, and 8 hours exposure to 100, 300, and 1000 parts per million (PPM) of all three chemicals. Neurochemical effects were determined following 8 hours exposure to 100, 300, and 1000 PPM of all three chemicals on whole brain levels of dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5HT). Response rate was significantly increased in all animals exposed to 1000 PPM of all three chemicals. Plots of successive subinterval response rate versus time indicated that low response rates were increased above control to a greater extent than high response rates. Significant increases in response rate were observed following toluene exposure, whereas both significant increases and decreases were observed following monochlorobenzene and styrene exposure in the 100-300 PPM range. Decreases in response rate were thought to be due to decreased inclination, rather than impaired physiologic capacity. Quarter life was characterized by a decreasing trend, with only monochlorobenzene resulting in a significant decrease in all animals. Significant increases were observed in DA levels, and decreases in NE levels, which may be correlated with the increase in response rate and decrease in quarter life. Monochlorobenzene resulted in the greatest number of significant increases in response rate and decreases in quarter life. Styrene resulted in significant increases in 5HT levels and toluene resulted in an increasing trend in 5HT levels, whereas monochlorobenzene did not affect 5HT levels. 5HT may be correlated with a slight disruptive effect on response rate with toluene and styrene, in comparison to monochlorobenzene.
Degree
Ph.D.
Subject Area
Public health
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