Ventral tegmental area dopamine neurons mediate the shock sensitization of acoustic startle: a potential site of action for benzodiazepine anxiolytics.
Dopamine (DA)-containing neurons in the ventral tegmental area (VTA) are thought to play an important role in fear motivation. The primary objective of the present study was to determine the connection between DA D2, gamma aminobutyric acid (GABA)A, and benzodiazepine receptors in the VTA and footshock-associated emotionality. Microinfusion of the DA D2 receptor agonist quinpirole. the GABA(A) receptor agonist muscimol, and the benzodiazepine receptor agonist flurazepam into the VTA was observed to suppress the shock enhancement of acoustic startle amplitudes. None of the drugs depressed baseline startle responding or footshock reactivity. The results indicate the involvement of VTA DA neurons in the fear-arousing properties of footshock and implicate the VTA as a possible neural site for the anxiolytic actions of benzodiazepines.