Predator stress induces behavioral inhibition and amygdala somatostatin receptor 2 gene expression.

Psychological stressors precipitate and maintain stress-induced psychopathology, and it is likely that altered amygdala function underlies some of the deleterious effects of psychological stress. To understand the mechanisms underlying the linkage between the response to psychological stressors and maladaptive or psychopathological responses, we have focused on amygdala responsivity in animal models employing species-specific psychological stressors. In the present study, we characterized the effects of a 15-min exposure to a natural predator, the ferret, on rat behavior and the expression of the somatostatin family of genes in the amygdala. We examined the somatostatin family of genes because substantial evidence shows that central somatostatin systems are altered in various neuropsychiatric illnesses. We report that rats respond to acute ferret exposure with a significant increase in fearful and anxious behaviors that is accompanied by robust amygdala activation and an increase in somatostatin receptor 2 (sst2) messenger RNA expression within the amygdala and anterior cingulate cortex. These studies are the first to show stress-induced changes in amygdala sst2 expression and may represent one mechanism by which psychological stress is linked to adaptive and maladaptive behavioral responses.