Triethylbenzene-induced sensorimotor neuropathy in rats.

1,2,4-Triethylbenzene (1,2,4-TEB) and 1,3,5-triethylbenzene (1,3,5-TEB) were administered orally to male Sprague-Dawley rats. Experimental and appropriate control rats were examined electrophysiologically for motor and sensory conduction velocities (MCV and SCV), and the amplitudes of the sensory (ASAP) and muscular action potentials (AMAP), at bi-weekly intervals. Oral administration of 1,2,4-TEB (200 or 400 mg kg-1, once daily, 4 days per week for 8 weeks) produced a time- and dose-dependent decrease in MCV, SCV, AMAP and ASAP. Rats treated with 1,2,4-TEB exhibited a bluish discoloration of the skin and the urine was greyish-greenish. No changes in MCV, SCV, AMAP and ASAP developed in rats given 1,3,5-TEB orally (200 or 400 mg kg-1, daily, 4 days per week for 8 weeks). The results indicate that 1,2,4-TEB is a neurotoxic isomer of TEB and that the presence of two ethyl radicals in the ortho-position on an aromatic ring could be a critical molecular arrangement resulting in chromogenic and neurotoxic properties.