Inability of thiol compounds to restore CNS arylsulfatases inhibited by methyl mercury

Arylsulfatase A and B activities have been analysed in different areas of the CNS (olfactory bulbs, cerebral hemispheres, cerebellum, medulla oblongata and spinal cord) during methyl mercuric chloride (MMC), N-acetyl-DL-homocysteine thiolactone (NAHT) and glutathione (GSH) treatment. Male albino rats were administered with two different doses of MMC (1 mg/kg and 10 mg/kg), NAHT (40 mg/kg and 80 mg/kg) and GSH (100 mg/kg and 150 mg/kg) for 2, 7 and 15 days, and sacrificed on the 3rd, 8th and 16th day, respectively. Likewise, eight groups of animals, after treatment for 7 days with MMC, were kept for another 7 days and sacrificed on the 15th day (normal withdrawal). Sixteen groups of 7 days MMC pretreated animals were given either NAHT or GSH for another seven days before sacrifice on the 15th day. The study revealed 1) a dose and duration dependent inhibition of the enzymes in all CNS areas, 2) a maximum inhibition of the enzymes among various hydrolases reported so far, and 3) none of the antagonists restored the enzymes significantly except for one group with NAHT. It is, therefore, concluded that arylsulfatases are more sensitive to MMC than other lysosomal enzymes, and the antagonists used here have not helped their restoration.