Systemic administration of atipamezole, a selective antagonist of alpha-2 adrenoceptors, facilitates behavioural activity but does not influence short-term or long-term memory in trimethyltin-intoxicated and control rats.

The present study used trimethyltin (TMT)-intoxicated rats as a model for the behavioural syndrome seen after neuronal damage to the limbic system. Behavioural assessments indicated increased locomotor activity and reduced number of groomings in an open-arena task in TMT-intoxicated (6.6 mg/kg as a free base) rats, as has been found previously. A novel finding was the severe deficit in swimming to a visible platform in the water maze task, with reduced swimming speed at the beginning of the training period. During the reacquisition phase of a radial arm maze task, TMT-intoxicated rats made more short-term and long-term memory errors, and their behavioural activity was increased in comparison with controls. The administration of atipamezole (300 micrograms/kg), a selective antagonist of alpha 2-adrenoceptors, enhanced locomotor activity compared to saline-treated rats, but these effects did not differ between the TMT group and their controls. Atipamezole did not enhance short-term or long-term memory in either TMT or control groups. Taken together, the present data indicate that TMT intoxication is a model for global dementia rather than for a specific loss of relational memory. Previous studies on the neurochemical effects of TMT and the alleviation or prevention of neurotoxicity of TMT are reviewed.