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CHANGES IN THE RAT EEG SPECTRA AND CORE TEMPERATURE AFTER EXPOSURE TO DIFFERENT DOSES OF CHLORPYRIFOS.
Citation:
Timofeeva, O. A. AND C J. Gordon. CHANGES IN THE RAT EEG SPECTRA AND CORE TEMPERATURE AFTER EXPOSURE TO DIFFERENT DOSES OF CHLORPYRIFOS. Presented at Society of Toxicology, San Francisco, CA, March 25-29, 2000.
Description:
Our previous study showed that single exposure to 25 mg/kg (p.o.) of organophsphate pesticide chlorpyrifos (CHP) led to significant alterations in all EEG frequency bands within 0.1-50 Hz range, reduction in core temperature (Tc) and motor activity (MA). The alterations in EEG persisted for 18 hr. In the present study we investigated if a lower dose of CHP can elicit specific EEG changes without affecting Tc and MA and if a higher dose can lead to persistent alterations. We recorded EEG, Tc and MA for 72 h of exposure (0, 10 or 40 mg/kg) to CHP in rats implanted with telemetric transmitters (Data Sciences). The recording and reference electrodes were placed in the occipital and frontal bones, respectively. 10 mg/kg of CHP produced clear but short-lasting (< 9 hr) EEG alterations, a decrease in Tc and MA. Alterations in EEG preceded the changes in Tc and MA. Significant EEG changes were observed in 5 out of 8 EEG bands (slow and fast theta, alpha/sigma, beta 2 and gamma 2). Changes in EEG bands were more profound and quicker following exposure to 40 mg/kg. These changes recovered approximately at the same time (by 18 hour) as after dose of 25 mg/kg. Surprisingly, 40mg/kg of CHP did not result in more rapid alterations in the slow theta, whereas changes in the slow theta consistently began a few hours later than shifts in the other EEG bands. CHP inhibits acetylcholinesterase, however, the delay in alteration of the slow theta following CHP did not occur after treatment with a muscarinic agonist oxotremorine (0.2mg/kg, s.c.). These suggest that CHP may exert a noncholinergic inhibitory effect on theta generation.
This abstract does not necessarily reflect US EPA policy.