Influence of psychogenic and neurogenic stressors on neuroendocrine and central monoamine activity in fast and slow kindling rats

The central neurochemical and neuroendocrine effects of a psychogenic (ferr et exposure) and a neurogenic (restraint) stressor were assessed in rats th at had been selectively bred for differences in amygdala excitability manif ested by either Fast or Slow amygdala kindling epileptogenesis. While these rat lines differ in their emotionality, their behavioral styles were depen dent on the nature of the stressor to which they were exposed. During restr aint, the Slow rats were mostly immobile, while Fast rats persistently stru ggled. In contrast, Fast rats were more immobile in response to the ferret. Yet, the more emotional Slow rats exhibited a greater corticosterone respo nse to the ferret, while comparable corticosterone responses between lines were evident following restraint. Although both stressors influenced norepi nephrine (NE), dopamine (DA) and/or serotonin (5-HT) activity in brain regi ons typically associated with stressors (e.g., locus coeruleus, paraventric ular nucleus of the hypothalamus, nucleus accumbens, prefrontal cortex), co nsiderable amine alterations were evident in the medial and basolateral amy gdala nuclei, but not in the central nucleus. Moreover, greater NE changes were apparent in the medial amygdala of the left hemisphere. Similarly, DA alterations also were greater in the left medial amygdala in response to st ressors. Despite very different behavioral styles, however, the two lines o ften exhibited similar amine alterations in response to both stressors. (C) 1999 Published by Elsevier Science B.V. All rights reserved.