Acute exposures to p-xylene and toluene alter visual information processing

Area of Science:

• Neurotoxicology
• Environmental Health
• Visual System Function

Background:

• Toluene and p-xylene are volatile organic compounds with widespread industrial and consumer use.
• Exposure to these solvents can pose risks to human health, including potential neurological effects.
• Understanding the neurotoxicological impact on the visual system is crucial for risk assessment.

Purpose of the Study:

• To investigate the effects of single oral and inhalation exposures to toluene and p-xylene on the visual system of Long-Evans hooded rats.
• To evaluate the functional integrity of the visual system using flash-evoked potentials (FEPs).
• To explore the relationship between solvent-induced FEP changes and arousal levels.

Main Methods:

• Rats received single oral doses of toluene (250-1000 mg/kg) and p-xylene (125-2000 mg/kg), or inhaled p-xylene (800-1600 ppm for 4 hr).
• Visual system function was assessed via flash-evoked potentials (FEPs), specifically analyzing peak N3 amplitude.
• Amphetamine was administered to establish the relationship between arousal and FEP peak N3 amplitude.

Main Results:

• Both oral toluene and p-xylene, at doses of 250 mg/kg and higher, significantly reduced FEP peak N3 amplitude.
• Inhalation of p-xylene at 1600 ppm also caused a significant depression in FEP peak N3 amplitude.
• The effects of oral solvent exposure persisted for at least 8 hours, while inhaled p-xylene's effects dissipated within 75 minutes.

Conclusions:

• Toluene and p-xylene exposure alters visual system processing, as indicated by FEP changes.
• The observed effects on FEP peak N3 amplitude may be secondary to changes in arousal or central nervous system excitability.
• These findings highlight the neurotoxic potential of common solvents on visual pathways.