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Susceptibility of the aging Brown Norway rat to carbaryl, an anti-cholinesterase-based insecticide: Thermoregulatory and cardiovascular responses.
Citation:
GORDON, C. J. Susceptibility of the aging Brown Norway rat to carbaryl, an anti-cholinesterase-based insecticide: Thermoregulatory and cardiovascular responses. Presented at Experimental Biology Conference, San Diego, CA, April 05 - 09, 2008.
Impact/Purpose:
The thermoregulatory and cardiovascular responses of young adult, mature adult, and aged Brown Norway (BN) rats were used to assess susceptibility to carbaryl, an anticholinesterase insecticide.
Description:
The proportion of aged in the United States is projected to expand markedly for the next several decades. Hence, the U.S.EPA is assessing if the aged are more susceptible to environmental toxicants. The thermoregulatory and cardiovascular responses of young adult, mature adult, and aged Brown Norway (BN) rats were used to assess susceptibility to carbaryl, an anticholinesterase insecticide. BN rats acquired from the National Institutes of Aging at 4, 12, and 24 m of age were implanted with transmitters to monitor heart rate (HR), core temperature (Tc), and motor activity (MA). Baseline data were monitored in undisturbed animals for 7 d. Age had little effect on HR or MA, but there was a significant increase in daytime Tc in the 24 m rats. Rats were dosed by oral gavage with corn oil or 25 mg/kg CAR. Exposure to CAR led to reductions in Tc and HR; however, the hypothermic and bradycardic effects were attenuated in aged rats. In another study, Tc and MA were followed for 22 m in BN rats beginning at 3 m of age. Mean 24 hr Tc decreased from 3 to 6 m, then increased gradually from 6 to 22 m. MA was unaffected by age. Overall, aging is associated with attenuation in the toxicological response to carbaryl. The subtle elevation in Tc with aging in the BN rat may be an important physiological biomarker for aging studies in rodent models. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.