Evaluation of antioxidant enzymes in response to predator odor stress in prefrontal cortex and amygdala

Conditions of stress can originate from diverse stimuli including physical, chemical, antigenic and psychological. The latter is processed in part via the hypothalamic-pituitary-adrenal (HPA) axis, with input from and communication between the amygdala (AM) and prefrontal cortex (PFC). The HPA axis generates an increase in circulating glucocorticoids, augmenting metabolism and, consequently, oxygen consumption, increasing the production of free radicals and reactive oxygen species (ROS). Exposure to predator odor as a model of non-invasive acute stress was used to evaluate the hypothesis that psychogenic stress can modify enzymatic antioxidant responses. The activities of various enzymes, catalase (CAT), cytosolic and mitochondrial superoxide dismutase (Cu, Zn-SOD and Mn-SOD, respectively) and glutathione S-transferase (GST), were determined in AM and PFC. Acute psychogenic stress inhibited CAT activity in the AM and PFC, and increased Mn-SOD activity in the PFC. These results demonstrate that different responses can be elicited by the same stressor in two separate brain regions involved in processing emotional stimuli, and that changes in specific antioxidant enzymatic responses can be seen with exposure to acute psychogenic stress.