Aims: 

Numerous environmental xenobiotics are neurotoxic. The best way to detect and follow-up nervous system damage would be the use of functional biomarkers but these still have to be worked out.

Methods: 

Adult male Wistar rats were anesthetized with urethane, the left hemisphere was exposed and a silver recording electrode was placed on the projection area of the whiskers. The whisker pad was stimulated with electric square pulses, in trains of 50, and the cortical response was recorded. The intensity of the stimulus was varied between 25% and 100% (just supramaximal), and its frequency, between 1 and 10 Hz. Three control records were taken, in 30 min interval, then one of the neurotoxicants (3-nitrporopionic acid, a mitochondrial toxin of microfungal origin: 20 mg/kg b.w.; dimethoate, an organophosphorus insceticide: 44 mg/kg b.w.; or manganese, a heavy metal: 50 mg/kg b.w. in chloride form) was injected ip. and further four records were taken.

Results: 

The effect of the three toxicants was dissimilar. Administration of dimethoate caused no significant change in the evoked response parameters or their dependence on stimulation. Mn caused increased amplitude and latency for strong stimuli, but intensified frequency-dependent fatigue. 3-nitropropionic acid caused amplitude increase without altered latency, and had less effect on frequency dependence.

Conclusion: 

The experiments carried out relied on techniques applied routinely also in human neurology. The alterations observed, if they prove to be sufficiently sensitive and/or specific in further studies, have the potency to be developed to functional biomarkers.