Vestibular compensation is affected by treatment with dopamine active agents

The aim of the present work was to examine the effects of postoperative treatments with agents active on dopaminergic system on vestibular recovery from the postural and ocular symptoms which follow a unilateral labyrinthectomy. Hemilabyrinthectomized guinea pigs were given a daily i.p. injection of bromocriptine (1 mg/kg) or sulpiride (10 mg/kg) or lisuride (0.1 mg/kg) or saline from post-operative days 1 to 21. Treatment with bromocriptine, a D2 agonist, accelerates compensation of postural and ocular symptoms. Conversely, treatment with sulpiride, a D2 antagonist, slows down the reachievement of symmetrical posture and stable ocular motility. Finally, the lisuride treatment, a drug active on D2 but also on other monoaminergic receptors, delays vestibular recovery so markedly to reach a "freezing" of vestibular deficits during drug treatment. These findings indicate that the already demonstrated role of dopamine in motor activity and learning can be extended to the learning processes required to recover from vestibular asymmetries.