Subchronic heavy metal and alcohol treatment in rats: Changes in the somatosensory evoked cortical activity

Young adult male Wistar rats were treated, by gavage, with 80 or 320 mg/kg Pb 2+ (lead acetate), 0.4 or 1.6 mg/kg Hg 2+ (mercuric chloride) or both by combining the lower doses. For combination with alco- hol, ethanol was added to the rats’ drinking water in 5 v/v %. After 12 weeks of treatment, electrophys- iological recording was made from the somatosensory cortex in urethane anaesthesia. Evoked potentials obtained by stimulation of the whiskers were recorded. Both metals, and alcohol alone, increased signif- icantly the latency of the evoked response. Alcohol seemed to abolish the effect of Pb, but not of Hg. Fatigue, calculated form the response amplitude, was increased by Pb and Hg treatment and this effect of Hg was reduced by ethanol. Evoked activity and its dynamic characteristics were sensitive to the com- plex neurotoxic effect induced in the rats and can provide a basis for developing functional marker

Neurotoxic and general effects of combined subchronic exposure of rats to insecticides and heavy metals

Three different insecticides: dimethoate, cypermethrin and amitraz were given, alone or combined with the heavy metals Pb, Hg and Cd, to male Wistar rats per os for 12 weeks from their 4th week of life. After the treatment period, the left hemisphere of the rats was exposed in urethane anaesthesia, and spontaneous and evoked cortical activity was recorded from the primary sensory areas. The effects of dimethoate on the spontaneous activity, and of dimethoate and amitraz on the evoked responses, were increased by the metal combination treatment, whereby the metals alone had no effect on the spontaneous and mild effect on the evoked activity. Finally, the animals were dissected, organ weights measured, and relative organ weights calculated. The weight gain of all treated groups was significantly retarded compared to the control. Several organ weights were also significantly reduced, mainly in groups receiving insecticide plus metal treatment. The toxic interactions observed in this work indicate that combined human exposure to environmental pesticide residues and heavy metals may have unexpectedly severe effects