[An experimental study on the neurotoxicity of 2-octanone and 2-hexanol, a metabolite of n-hexane].

An electrophysiological study of the neurotoxicity of 2-octanone (an analogue of methyl n-butyl ketone) and 2-hexanol (a metabolite of n-hexane) was conducted on rats as a part of the study to determine the specific molecular arrangement required for the development of peripheral neuropathy. The compound 2-octanone or 2-hexanol was administered subcutaneously in the daily dose of 400 mg/kg of each compound into the back of seven rats, weighing 290 g, 5 days per week for a period of 21 weeks. Animals treated with 2-octanone for 21 weeks failed to exhibit apparent clinical and neurophysiological evidence except a slight inhibition of weight gain and narcotic effects after treatment with the compound. The same doses of 2-hexanol for 21 weeks caused hypersalivation, gait disturbances, crossing phenomena of hind limbs and a failure of normal growth. Retardation of the conduction velocity in the motor and sensory nerve fibers and the prolonged motor latencies of the tail nerves (distal part) began to appear at the 14th week of the experiment when 9.6 g in the total dose had been given to each animal. These changes were intensified in the subsequent course of the experiment. Our previous experiments and the present results showed that n-hexane barely produced peripheral neuropathy in doses over 10.5 g, and that 2-hexanone (MBK), 2,5-hexanediol or 2,5-hexanedione never failed to produce a neuropathy even in doses less than 9.6 g of each compound. The above results suggest that the neurotoxic potency of 2-hexanol is greater than that of n-hexane but less than that of MBK, 2,5-hexanediol or 2,5-hexanedione.