Oxidative stress

What is oxidative stress?

While oxygen is a vital component of life, some oxygen-based compounds called free radicals can be toxic due to their highly unstable nature. The key free radical classes are the reactive oxygen species and reactive nitrogen species, and they are formed as by-products of normal metabolism. Under normal conditions, these free radicals are tightly monitored and controlled by stringent protective barriers, such as their rapid removal from cells and antioxidant enzymes that break them down.

At tightly maintained concentrations, free radicals play an important role in cellular signalling, immune responses and cell growth. However, excess free radicals can result from interruption of the antioxidant defense barrier, or from excess production. This can cause oxidative stress, resulting in structural damage to cellular proteins, fats, carbohydrates and nucleic acids (DNA and RNA). Severe oxidative stress can result in failure of cell growth, apoptosis and cell necrosis.

What is the evidence for oxidative stress in people with bipolar disorder?

Moderate to high quality evidence finds large increases in lipid peroxidation, nitric oxide, and DNA/RNA damage in people with bipolar disorder compared to controls. There were no differences in protein carbonyl or 3-nitrotyrosine.

Moderate quality evidence finds large increases in malondialdehyde, thiobarbituric acid reactive substances, total nitrites, catalase, and glutathione transferase in people with bipolar disorder compared to controls. There were medium-sized increases in glutathione, apart from in the anterior cingulate where glutathione was reduced in bipolar II disorder patients. There were medium-sized increases in uric acid, particularly during mania. Superoxide dismutase was increased, and glutathione peroxidase was decreased only in patients who were medication-free and in a manic phase. There were no differences in levels of zinc.

December 2021

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Last updated at: 3:57 pm, 12th December 2021
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