Influence of GABAA and GABAB Receptor Activation on Auditory Sensory Gating and Its Association with Anxiety in Healthy Volunteers.

Background: Dysfunctional sensory gating in anxiety disorders, indexed by the failure to inhibit the P50 event-related potential (ERP) to repeated stimuli, has been linked to deficits in the major inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Aims/Methods: This study, conducted in 30 healthy volunteers, examined the acute effects of GABA(A) (lorazepam: 1 mg) and GABA(B) receptor (baclofen: 10 mg) agonists on P50 measures of auditory sensory gating within a paired-stimulus (S1-S2) paradigm and assessed changes in gating in relation to self-ratings of anxiety. Results: Compared to placebo, lorazepam reduced ERP indices of sensory gating by attenuating response to S1. Although not directly impacting P50 inhibition, baclofen-induced changes in gating (relative to placebo) were negatively correlated with trait but not state anxiety. Conclusions: These preliminary findings support the involvement of GABA in sensory gating and tentatively suggest a role for GABA(B) receptor signaling in anxiety-associated gating dysregulation.