Stress-Induced Enhancement of the Startle Reflex

Abstract

Abstract : The goals of the research are to study neural systems involved in the production and inhibition of fear and anxiety. Previous research has found that the acoustic startle reflex is sensitive to both fear and stress. Many effects produced by fear or stress are mimicked by infusion of the peptide corticotropin releasing factor (CRF) directly into the brain. This year we have found that infusion of CRF into the brain causes a pronounced, dose-dependent enhancement of the acoustic startle reflex in rats. This excitatory effect was blocked by a CRF antagonist or by lesions of the amygdala, a brain structure known to be involved in fear and stress. The present data indicate that the amygdala is part of the neural circuitry required for CRF to elevate startle. Because startle is mediated by a well-defined neural pathway, CRF-enhanced startle is a useful behavioral' assay to analyze the neural systems upon which exogenous CRF acts to produce its behavioral effects. Startle, Fear, Stress, Amygdala, Corticotropin releasing fact.