Abstract
In order to elucidate the biological effect of LaCl3·7H2O, a 28-day repeated oral administration test was conducted in Slc : Wistar rats of each sex by gavage at doses of 0, 40, 200 or 1000 mg/kg/day with the pair feeding group. Two more groups (0 mg/kg, 100 mg/kg) of both sexes were appended as 14-day recovery groups after the 28-day administration. Body weight and food consumption were measured, and hematological, serum-biochemical and histopathological examination were performed. The concentrations of lanthanum and essential elements in organs were determined by ICP-MS or ICP-AES. The number of eosinophilic leucocytes increased in rats of both sexes dose-dependently. At a dose of 1000 mg/kg, hyperkeratosis in the forestomach of both sexes, eosinophilic leucocyte infiltration in the submucosa of the stomach of both sexes, erosion and dilatation of acinus of the glandular stomach in males, and swelling of the glandular stomach epithelium in females were found. These results suggest that lanthanum is irritant to the stomach mucosa. At doses higher than 200 mg/kg, a significant decrease of the serum cholinesterase activity was observed only in females. The serum transaminase activity increased in both sexes at a dose of 1000 mg/kg. This finding is suggestive of hepatotoxicity, although there were no histopathological changes of the liver. Lanthanum was accumulated in the liver, kidney, spleen and femur in a dose-dependent manner. The accumulation of lanthanum in the liver was the highest and higher level was found in the liver of female than of male. The sex-dependent differences were demonstrated in terms of the irritating reaction of the stomach mucosa, the reduction of the serum cholinesterase activity and the accumulation of lanthanum in the liver. The all over data make it clear that lanthanum was absorbed through the digestive tract. Dose-dependent decreases of iron concentrations in the liver, kidney and spleen, and those of barium and strontium concentrations in the femur were observed in both sexes.
