Alterations in monoamine levels and oxidative systems in frontal cortex, striatum, and hippocampus of rat brain during chronic unpredictable stress. (extra Credit)

Ahmad, A., Banu, N., Palit, G., & Rasheed, N. (2010). Alterations in monoamine levels and

Oxidative systems in frontal cortex, striatum and hippocampus of rat brain during

Chronic unpredictable stress. Stress, 13(4), 355-364. doi: 10.3109/10253891003667862

Retrieved from EbscoHost

Physiological and behavioral changes can be caused by stress. The length and type of stress determine if the response to it is damaging or beneficial to the brain. Two areas in the brain that control stress responses are the Hypothalamic-pituitary-adrenal axis (HPA) and the monoamingeric sympathetic nervous system. In this study chronic stress (CUS) is used to see if the frontal cortex and striatum are effected by the amounts of dopamine and serotonin released as a stress response. Chronic stress can cause irreversible effects on multiple cell functions because it impairs the brains defense system. 48 adult male rats were placed three per cage in both groups. Temperature, sleep-wake cycles, and food were all controlled. The non stressed group were left alone and unbothered in their cages for seven days. The CUS group were exposed to two types of stress varying in intensity and on an unpredictable schedule for seven days. The stressors for the CUS group were tail pinching, loss of food and water, isolation, being restrained, exposure to lower temperatures, wet cages, sleep-wake cycle reversal, and forced swimming. At the end of the seven days the CUS group was divided into two groups. Group A was killed immediately following the last stressor and group B was killed 24 hours later. The brains were then removed, dissected and weighed. The frontal cortex of both CUS groups showed a significant decrease in dopamine and serotonin when compared to the control group. The same effect was found in the striatum and the hippocampus. CUS also led to behavioral depression and chemical changes because the decrease of dopamine and serotonin slowed the brains ability to respond to stressors. Ahmad, et al. believes that because the neurological and antioxidant defenses are inhibited by stress they are connected biologically to many stress induced brain disorders.