In the case of excessive ROS production, endogenous defense mechanisms against ROS may not be sufficient to suppress ROS-associated oxidative damage. Consequently, ROS attack terminally differentiated neuronal cells, which are in a post-mitotic state unlike other cell populations (e.g., skin, blood, and connective tissue) therefore, neuronal cells are particularly sensitive to oxidative stress, leading to nerve damage. ![]() Moreover, ROS are constantly generated as by-products of normal metabolism and neurotransmitter metabolic processes. The brain is one of the most sensitive target tissues to oxidative stress because of its increased level of ROS and decreased level of antioxidants. Many neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are associated with an excessive production of ROS and free radicals. Recent studies have suggested that long-term exposure to physiological or psychological stress is associated with the production of oxidative species, which cause the accumulation of oxidative damage to biomolecules (lipids, proteins, and DNA) in the brain, eventually leading to many neurodegenerative diseases. This conclusion is demonstrated by Rooibos tea’s ability to (i) reverse the increase in stress-related metabolites (5-HIAA and FFA), (ii) prevent lipid peroxidation (LPO), (iii) restore stress-induced protein degradation (PD), (iv) regulate glutathione metabolism (GSH and GSH/GSSG ratio), and (v) modulate changes in the activities of antioxidant enzymes (SOD and CAT).ĭuring cellular redox, the human body constantly generates free radicals (superoxide and hydroxyl radicals) and other reactive oxygen species (ROS) (hydrogen peroxide, nitric oxide, peroxynitrile, and hypochlorous acid) as a result of aerobic metabolism. Therefore, in the present study, we propose that immobilization-induced oxidative stress was significantly attenuated by treatment with Rooibos tea. Animals subjected to chronic restraint or immobilization are widely believed to be a convenient and reliable model to mimic psychological stress. However, most animal models of stress, such as cold-restraint, electric foot shock, and burn shock, usually involve physical abuse in addition to the psychological aspects of stress. ![]() An optimal animal model for stress should show the features of a stress response and should be able to mimic natural stress progression. In particular, Rooibos tea might be a good source of antioxidants due to its larger proportion of polyphenolic compounds. Dietary antioxidants have been shown to protect neurons against a variety of experimental neurodegenerative conditions. Compared with other organs, the brain appears especially susceptible to excessive oxidative stress due to its high demand for oxygen. Exposure to chronic psychological stress may be related to increased reactive oxygen species (ROS) or free radicals, and thus, long-term exposure to high levels of oxidative stress may cause the accumulation of oxidative damage and eventually lead to many neurodegenerative diseases.
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