Tissue-Specific Changes In Antioxidant Defence During Ageing: The Effect Of Chronic Cold Exposure
As we age, our bodies experience a gradual imbalance in “redox homeostasis,” which is essentially the delicate equilibrium between harmful reactive molecules and the protective “antioxidant defense” system. This imbalance can lead to cellular damage and contribute to the aging process. While many factors influence aging, the impact of long-term exposure to cold temperatures has been less understood.
Recent research sheds light on how chronic cold exposure affects the body’s antioxidant defenses in different tissues of older rats. The study found that with natural aging, the activity of certain protective enzymes, like catalase and glutathione peroxidase (GSH-Px), decreased in some fat tissues, specifically retroperitoneal white adipose tissue (rWAT) and interscapular brown adipose tissue (iBAT). These enzymes are crucial components of the antioxidant defense system, working to neutralize damaging molecules.
However, when aged rats were exposed to a colder environment (4°C), their bodies responded by boosting these antioxidant defenses. The activity of several key antioxidant components, including catalase, GSH-Px, glutathione reductase (GR), thioredoxin reductase (TR), glutathione S-transferase (GST), and total glutathione (GSH), increased in rWAT, iBAT, and even skeletal muscle. This suggests that prolonged cold can stimulate the body’s protective mechanisms in these areas.
Interestingly, not all tissues responded in the same way. The activity of certain enzymes like copper-zinc superoxide dismutase (CuZnSOD) and manganese superoxide dismutase (MnSOD) remained unchanged across all groups and tissues. Furthermore, the liver did not show any significant changes in its antioxidant defense components, indicating a “tissue-specific” response to cold exposure. This means that the benefits of cold exposure on antioxidant defenses are not uniform throughout the body, but rather targeted to specific organs, particularly those involved in heat production like brown adipose tissue.
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