Subacute neurobehavioral effects of dermally-applied alphacypermethrin in rats

Because of the common usage for the synthetic pyrethroid alphacypermethrin in agriculture, public health and veterinary medicine, the objective of this study was to determine the potential neurobehavioral effects of dermally-applied alphacypermethrin in rats for 28 days. A total of 40 adult Wistar rats were randomly divided into four groups (5 females and 5 males in each group): only vehicle (70% alcohol) was applied to the control group whereas the 3 other groups were treated with 100,200 and 300 mg/kg b.w pyrethroid, respectively. Mortality and clinical signs were observed daily while locomotor activities, pain sensitivity, motor coordination, catatonia, body weights, food consumptions and open-field assessments (counts of urination and defecation, agitation, stereotypy) were measured weekly. At this end of experimental period, haematological parameters were assessed and all animals were necropsied. Rats dermally treated with 100 or 200 mg/kg α-cypermethrin exhibited neither clinical and behavioural alteration nor haematological change or macroscopic lesion. However, alphacypermethrin at the highest dose (300 mg/kg) induced motor incoordination in males and decrease of pain sensitivity in females. These data emphasizes the interest of neurobehavioral tests for risk assessment of dermal alphacypermethrin application.