Organic mercury (Hg2+) is the cause of environmental damage and disease. Exposure to Hg2+ can be due to dental amalgams, seafood, chlor-alkali plants, gold extraction, mercury extraction and mining or mercury thermometers. Hg2+ can seriously impair the immunity.
The thymus gland is a target of Hg2+. The thymus is important for T lymphocyte development. The thymus produces thymulin, a hormone which is zinc dependent. Thymulin levels decline with chronic infections and with ageing. There is a connection between thymulin production and nitric oxide (NO) production. NO is produced from l-arginine, an essential amino acid.
Metallothioneins (MTs) are proteins involved with heavy metal detoxification and with the regulation of blood levels of essential metals, such as zinc and copper. MTs contain a large amount of cysteine amino acid. Hg2+ can alter the function of MTs by causing them to release their zinc ions. The reduced zinc suppresses NOS (nitric oxide synthase) activity, which reduces NO production. NO is important to good immune function.
Other nutritional factors which alter mercury toxicity are alpha-lipoic acid, N-acetylcysteine, glutathione, zinc and selenium.
The NO-NOS pathways and metallothioneins (MTs) were studied by the authors in regard to the ability of l-arginine to reverse the damage by Hg2+ to the thymus gland. Mice were given high or low doses of Hg2+ by injection, with and without l-arginine in the drinking water. Mice given only salt water were used as controls for comparison. Thymus weight and thymulin production were measured to evaluate the success of the therapy.
Mice which received Hg2+ without arginine showed increased thymic mercury, reduced NOS activity, lower nitrite and nitrate blood levels and increased MTs. (Nitrites and nitrates were determined since NO has a half-life of only 2-3 seconds in the blood.) Arginine treatment resulted in lower Hg2+ levels in the thymus and improved levels of NOS, nitrites and nitrates. The reduced Hg2+ could have been due to the increased NO production and NO-MTs interactions.
Thymulin production was reduced in all mice which received Hg2+. Mice which received Hg2+ and l-arginine had thymulin levels close to those of the control mice and “significantly” improved over those of mice receiving mercury, only.
Chelation therapy to bind mercury is used in cases of acute toxicity. The agents have side effects and have not clearly been shown to be effective in reducing mercury. Some chelation is oral and some is intravenous.
CONCLUSION: L-arginine can be used as a preventive of mercury damage and to partially repair damage to the thymus caused by organic mercury.
NOTE: T lymphocytes are white blood cells which become mature in the thymus. They are part of cell-mediated immunity.
Read a list of arginine containing foods.