Methylmercury chloride-induced and antagonist-reverted succinic dehydrogenase changes in the brain and trigeminal ganglia of the rat.

The effect of methylmercury chloride (MMC) toxicity and its antagonism by chelating agents (N-acetyl-DL-homocysteine thiolactone and 2,3-dimercaptosuccinic acid) on succinic dehydrogenase (SDH) activity of fore-, mid-, and hindbrain and trigeminal ganglia of rats is reported in this study. A dose of 10 mg MMC/kg body weight was injected subcutaneously for 2, 7, and 15 days. The chelating agents were also injected subcutaneously in two separate groups of MMC-treated animals except in group 3. In the latter case MMC was injected in two groups of rats for 7 days, and thereafter antagonists were administered daily (40 mg/kg) for 1 week. The result shows inhibition of the enzyme with MMC in all groups and its restoration by N-acetyl-DL-homocysteine thiolactone; 2,3-dimercaptosuccinic acid, however, further reduced the enzyme level. The significance of inhibition of the enzyme in relation to tissue respiration and ATP production is discussed and the capacities of antagonists in the restoration of the SDH level are also analyzed.