The environmental pollutant endosulfan disrupts cerebral cortical function at low doses

Area of Science:

• Neuroscience
• Toxicology
• Electrophysiology

Background:

• Endosulfan is a neurotoxic pesticide known to induce convulsions and potential brain damage.
• Early diagnosis of endosulfan intoxication is challenging due to non-specific pre-convulsive neurological signs.

Purpose of the Study:

• To investigate if electrophysiological exploration of the cerebral cortex can identify objective signs of endosulfan intoxication at sub-convulsive doses.
• To establish endosulfan's dose-response effects on cortical evoked potentials and EEG power.

Main Methods:

• Adult Sprague-Dawley rats were administered intravenous endosulfan (0.5-4mg/kg) under urethane anesthesia.
• Electroencephalogram (EEG) power and evoked potentials (EP) to forepaw stimulation were recorded from somatosensory and visual cortical areas.
• Arterial blood pressure, heart rate, and body temperature were monitored throughout the experiment.

Main Results:

• Endosulfan induced a dose-related increase in EP amplitudes across all cortical areas studied.
• Significant increases in EP peak amplitude were observed at doses of 1, 2, and 4mg/kg endosulfan.
• A shift in EEG power to higher frequencies (alpha and beta bands) was noted only at the highest dose (4mg/kg).

Conclusions:

• Endosulfan significantly increases cortical evoked potential amplitudes at doses below those causing convulsions.
• These electrophysiological changes may serve as a non-invasive biomarker for detecting low-level endosulfan intoxication.
• This approach could aid in establishing No Observed Adverse Effect Levels (NOAEL) and Lowest Observed Adverse Effect Levels (LOAEL) for endosulfan.