Corticotropin-releasing factor potentiates acoustic startle in rats: blockade by chlordiazepoxide

A series of experiments was performed to investigate the effects of corticotropin-releasing factor (CRF) on the amplitude of the acoustic startle response (ASR) in rats. Intracerebroventricular (ICV) administration of 1 microgram rat CRF significantly potentiated acoustic startle amplitude; these effects were reversed in a dose-dependent manner by pretreatment with the benzodiazepine chlordiazepoxide (CDP). Doses of CDP that antagonized CRF-potentiated ASR did not lower startle baseline or antagonize amphetamine- or strychnine-potentiated ASR. These results suggest that CRF has "anxiogenic" properties and may serve as a neuroendocrine modulator of stress-enhanced behaviors.