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AGE-RELATED EFFECTS OF TOLUENE ON THE MOTOR ACTIVITY OF BROWN NORWAY RATS.
Citation:
MACPHAIL, R. C., J. D. FARMER, AND K. JAREMA. AGE-RELATED EFFECTS OF TOLUENE ON THE MOTOR ACTIVITY OF BROWN NORWAY RATS. Presented at Society of Toxicology, Charlotte, NC, March 26 - 29, 2007.
Description:
Senescence raises many uncertainties regarding susceptibility to environmental exposures. Compromises in reserve and repair mechanisms, and alterations in metabolic capacity, may make the aging population more susceptible to environmental contaminants. Additionally, increased variability between individuals might complicate accurate assessment of susceptibility in the aging population. This study was designed to assess the relative sensitivity of aging Brown Norway (BN) rats to the behavioral effects of toluene. BN rats have been used extensively in aging research, although little is known about how they respond to environmental chemicals. BN rats were supplied by the National Institute on Aging at 4, 12 and 24 months of age (N=8 per age). The rats were tested weekly in a commercial photocell device for measuring motor activity during 30-min sessions. Toluene was administered in corn oil by gavage, 30-min prior to testing, in doses of 0, 300, 650 and 1000 mg/kg. Weekly dosing and testing continued until all rats received each treatment. Following vehicle, horizontal activity was highest in the 4-month rats and lowest in the older rats; vertical activity also decreased with age. When expressed relative to vehicle-control values, toluene produced dose-related increases in horizontal activity and decreases vertical activity. Toluene effects were most pronounced in the oldest rats. The oldest rats were, however, the heaviest and therefore received a larger amount of toluene (as mg/kg) than the younger, lighter rats. To evaluate this potential confound, all rats were given the same amount of toluene regardless of body weight. Age-related differences in sensitivity were still obtained. These results indicate advancing age may increase susceptibility to toluene.