MECHANISMS OF NEUROTOXIC ACTION OF 1,1,1-TRICHLORO-2,2-BIS(p-CHLOROPHENYL)ETIIANE (DDT) IN IMMATURE AND ADULT RATS

¹ Departments of Environmental Toxicology and Animal Physiology, University of California, Davis, California

The neurotoxicity of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) was compared in 10- and 60-day-old rats to determine some of the factors contributing to the lesser sensitivity of immature rats to DDT. The effects of lethal doses of DDT on respiration, electrocardiogram, brain electrical activity and body temperature were studied in adult rats with chronically implanted brain electrodes. Also, the effect of DDT on body temperature was compared in young and adult rats. DDT poisoning in both young and adult rats was characterized by hyperexcitabiity, intense tremoring and respiratory failure preceded by a state of prostration. In the adult rat, DDT caused an increase in respiration and heart rate and a lethal increase in body temperature (40-42°C) prior to death. In contrast to this the body temperature of the immature rat decreased during acute DDT intoxication. It is suggested that in both the immature and adult rat, death may be due to a direct depressant effect of DDT on respiratory mechanisms at the peripheral, spinal or brainstem level. However, in the adult rat there are additional toxic responses, i.e., seizures and hyperthermia, not observed in the young rat which may account for the increased lethality of DDT in mature animals.