Effects of Subchronic Exposure to Manganese Chloride on Tissue Distribution of Three Essential Elements in Rats

Abstract

A subchronic treatment of manganese chloride (MnCl2) was administered to rats by intraperitoneal (IP) route (6 mg Mn/kg of body weight/day) or oral (PO) route (75 mg Mn/kg of body weight/day) for 4 weeks. After a 2-week interval, different tissues plus the blood were sampled. An increase of manganese (Mn) concentrations was observed in most of the tissues, particularly in the nervous system (brain and spinal cord) and in femur, with the exception of liver, adrenal glands, and esophagus by IP treatment and liver, jejunum, ileum, and adipose tissue by PO treatment. Tissue accumulation of Mn was greater by IP treatment. During each of the two treatments, urinary and fecal excretion of Mn increased. The presence of Mn observed in whole blood, bone marrow, and spleen after IP treatment could be explained by the existence of competition between iron (Fe) and Mn that may appear, notably, as a disturbance in the functioning of the respiratory chain in the cells (incomplete O2 reduction and formation of free radicals and oxygenated compounds), leading to cellular degeneration. In these experimental conditions, no obvious competition could be observed with zinc (Zn) and copper (Cu). Despite a large accumulation of Mn in the bones, no disturbance of the phosphorus-calcium metabolism was observed.