Abstract
Increased locomotor activities as well as circling behaviours in animals with bilateral vestibular loss are well documented in the literature. However, the cause of these behavioural changes are still unknown. Dysfunction of the striatal dopaminergic system is responsible for a number of known movement disorders. The D2 dopamine receptor is known to be involved in the regulation of behaviour. The aim of this study was to investigate the effects of the D2 antagonist, eticlopride, in rats 2 months following bilateral vestibular deafferentation surgery, using an open field maze to test locomotor behaviours and the 5-choice serial reaction time task to measure impulsivity. The levels of the D2 receptor in the striatum and frontal cortex were then measured using western blotting. BVD rats were found to show behaviours already reported in animals with vestibular loss. Treatment with eticlopride was found not to inhibit these behaviours. There were no changes in the amount of the D2 receptor in the striatum or frontal cortex at one or six months post surgery. The main effect of D2 receptor inhibition in this study was a decreased response to the drug in BVD rats compared to shams at the 0.02 mg/kg dose. Blockade of the D2 receptor did not inhibit the cause of the behavioural changes in BVD rats. However, the drug did produce a surgery dependent effect. This suggests that while these behaviours are not due to the D2 receptor, there is a change in the dopaminergic pathways in BVD rats.