CARBON-DISULFIDE NEUROTOXICITY IN RATS - VII - BEHAVIORAL-EVALUATIONSUSING A FUNCTIONAL OBSERVATIONAL BATTERY

The neurobehavioral consequences of inhalational exposure to carbon di sulfide (CS2) were evaluated as part of a joint project between the Na tional Institute of Environmental Health Sciences and the U.S. Environ mental Protection Agency. Behavioral changes in rats were measured usi ng a functional observational battery (FOB), which is a series of obse rvations and manipulations designed to assess the neuronal integrity o f autonomic, motor, sensory, and integrative functions. Young adult ma le and female Fischer-344 rats were exposed to one of four CS2 concent rations (0, 50, 500, or 800 ppm, six hours/day, five days/week) and te sted at the end of one of several exposure durations (two, four, eight , or 13 weeks). All rats were also tested before exposure began to obt ain baseline values. Neuromuscular deficits which were more pronounced in the hindlimbs, e.g., decreased strength and gait alterations, were detected in rats of both sexes. These changes were closely related to CS2 concentration and exposure duration, with mild gait changes evide nt after only two weeks of exposure. Other effects, mostly observed at 13 weeks, included decreased responsiveness to a visual stimulus and mild tremors. Reactivity in response to handling was generally increas ed, and excitability in the open field was decreased, in rats tested a fter the shorter exposures (two and four weeks). Thus, the exposure-co ncentration and -duration characteristics of the neuromotor syndrome p roduced by CS2 were detected and defined using the FOB. These studies provide a more complete evaluation of rats under these CS2 exposure co nditions, which can then be used to compare with other mechanistic-rel ated endpoints from this collaborative study. (C) 1998 Intox Press, In c.