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CARDIOVASCULAR AND THERMOREGULATORY RESPONSE TO ORAL TOLUENE IN THE RAT.
Citation:
Gordon, C J., W M. Oshiro, T E. Samsam, P Becker, AND P J. Bushnell. CARDIOVASCULAR AND THERMOREGULATORY RESPONSE TO ORAL TOLUENE IN THE RAT. Presented at Society of Toxicology, New Orleans, LA, March 06 - 10, 2005.
Description:
Toluene and other volatile organic compounds have often been shown to affect behavior in animals when given by inhalation, and less effective when given orally. Previous work showed that toluene increased heart rate (HR) and motor activity (MA), and reduced core temperature (Tc) in rats inhaling toluene for 1 hour while performing an operant task. It is important to assess the effect of oral toluene on autonomic and motor conditions under resting conditions. To this end, the effects of oral toluene on HR, Tc, and MA in resting, unrestrained rats were determined. Adult rats (male, Long-Evans) were surgically implanted with radiotransmitters to monitor HR, Tc, and MA. Toluene was administered by gavage in corn oil at doses of 0, 0.4, 0.8, and 1.2 g/kg at 11:30 hr while the telemetry data were monitored over 48 hours at 22 oC. Dosing with corn oil led to transient elevations in HR, Tc, and MA, a response attributed to the stress of handling, that recovered within 2 hr. All doses of toluene led to transient increases in HR that exceeded the control response during the first 0.5 hr after dosing. The higher doses of toluene elevated HR for more than 6 hr after dosing. HR remained elevated above controls by approximately 25 and 50 b/min in the 0.8 and 1.2 g/kg groups, respectively. Tc increased above controls for several hours after 0.8 g/kg toluene. There was a transient reduction in Tc below controls following 1.2 g/kg toluene during the first hour followed by a progressive elevation for 4 hr after dosing. MA of the 0.8 and 1.2 g/kg groups increased transiently above controls then recovered. There was a secondary rise in MA in the 1.2 g/kg group persisting for several hours after dosing. Overall, toluene at doses of 0.8 and 1.2 g/kg induced a marked tachycardia, hyperactivity, and hyperthermia. These autonomic effects developed in spite of a lack of effect of the same oral doses of toluene on operant behavior. It will be important to compare oral and inhaled toluene exposure in rats maintained under rest and working (i.e., operant behavior) conditions. This abstract does not reflect EPA policy.