l-Baclofen-sensitive GABAB binding sites in the medial vestibular nucleus localized by immunocytochemistry

l-Baclofen-sensitive GABA_B binding sites in the medial vestibular nucleus (MVN) were identified immunocytochemically and visualized ultrastructurally inl-baclofen-preinjected rats and monkeys, using a mouse monoclonal antibody with specificity for the p-chlorophenyl moiety of baclofen. Saline-preinjected animals showed no immunostain. In drug-injected animals, there was evidence for both pre- and postsynaptic GABAergic inhibition in MVN mediated by GABA_B receptors. These neural elements could be utilized in control of velocity storage in the vestibulo-ocular reflex.