Toxicological and Pharmacological Studies on Magnesium Deficiency in Rats : Histamine-Metabolizing Enzymes in Some Tissues of Magnesium-Deficient Rats

Abstract

The effects of dietary magnesium(Mg) deficiency on histamine-metabolizing enzymes were studied in young Wistar rats with a mean initial body weight of 60 g. Histidine decarboxylase(HDC) activity was observed in the stomach, skin, lung, spleen and liver, but not detected in the duodenum or kidney in the control rats. In 4 days of feeding an Mg-deficient diet(Mg:0.001%), the HDC activity of the spleen, lung and liver appeared to rise until the 8th day of Mg deficiency. In the skin, the HDC activity was the highest on the 4th day of Mg deficiency, then decreased on the 6th day, and increased again on the 8th day. Diamine oxidase(DAO) activity was high in the duodenum, but low in the other tissues examined in control rats. In 2 to 4 days of depletion of Mg in the diet, the DAO activity decreased in all the tissues examined to about 1/2 that of the control group. Histamine methyl transferase(HMT) activity was high in the kidney, liver and duodenum in control rats. HMT activity observed in these tissues did not change significantly during the 8-day Mg absence in the diet. These results suggest that both the increased HDC and the decreased DAO activities contribute to the increase in the histamine content in some tissues in Mg-deficient rats.